1
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Xu H, Wang L, Chen L, Ma X, Hu W, Zhao J, Tan S, Wang B. Stabilizing Fe Single Atoms on Rutile-TiO 2(110) Surface Via Atomic Substitution. J Phys Chem Lett 2024; 15:9272-9279. [PMID: 39234986 DOI: 10.1021/acs.jpclett.4c02189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/06/2024]
Abstract
Stable anchoring of dispersed metal atoms through either surface adsorption or lattice substitution on support surfaces is a prerequisite for highly efficient catalytic performance. Atomic-level insights into these processes are necessary to understand the metal-support interactions. Here, we identify multiple Fe single-atom configurations on the rutile-TiO2(110) surface using scanning tunneling microscopy (STM) and density functional theory (DFT). Our results show that an Fe atom can either adsorb on a surface O site (configuration I) or stably substitute a surface lattice Ti atom (configuration II). A transformation from configuration I to configuration II can be induced by STM manipulation. Furthermore, the substitutional Fe atom can capture an additional Fe atom to form a dual Fe-Fe complex (configuration III). DFT calculations reveal that these Fe species contribute different states in either the bandgap or the conduction band. These atomistic insights pave the way for interrogating the integrated performance of nonprecious, TiO2-supported Fe single-atom catalysts.
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Affiliation(s)
- Huimin Xu
- Hefei National Research Center for Physical Sciences at the Microscale and New Cornerstone Science Laboratory, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Lei Wang
- Hefei National Research Center for Physical Sciences at the Microscale and New Cornerstone Science Laboratory, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Linjie Chen
- Hefei National Research Center for Physical Sciences at the Microscale and New Cornerstone Science Laboratory, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Xiaochuan Ma
- Hefei National Research Center for Physical Sciences at the Microscale and New Cornerstone Science Laboratory, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Wei Hu
- Hefei National Research Center for Physical Sciences at the Microscale and New Cornerstone Science Laboratory, University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei, Anhui 230088, China
| | - Jin Zhao
- Hefei National Research Center for Physical Sciences at the Microscale and New Cornerstone Science Laboratory, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Shijing Tan
- Hefei National Research Center for Physical Sciences at the Microscale and New Cornerstone Science Laboratory, University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei, Anhui 230088, China
| | - Bing Wang
- Hefei National Research Center for Physical Sciences at the Microscale and New Cornerstone Science Laboratory, University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei, Anhui 230088, China
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2
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Yim CM, Allan M, Pang CL, Thornton G. Scanning Tunneling Microscopy Visualization of Polaron Charge Trapping by Hydroxyls on TiO 2(110). THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2024; 128:14100-14106. [PMID: 39193256 PMCID: PMC11345827 DOI: 10.1021/acs.jpcc.4c03751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2024] [Revised: 07/28/2024] [Accepted: 07/30/2024] [Indexed: 08/29/2024]
Abstract
Using scanning tunneling microscopy (STM), we investigate the spatial distribution of the bridging hydroxyl (OHb) bound excess electrons on the rutile TiO2(110) surface and its temperature dependence. By performing simultaneously recorded empty and filled state imaging on single OHbs at different temperatures in STM, we determine that the spatial distribution of the OHb bound excess electrons retains a symmetric four-lobe structure around the OHb at both 78 and 7 K. This indicates that OHbs are much weaker charge traps compared to bridging O vacancies (Ob-vac). In addition, by sequentially removing the capping H of each OHb using voltage pulses, we find that the annihilation of each OHb is accompanied by the disappearance of some lobes in the filled state STM, thus verifying the direct correlation between OHbs and their excess electrons.
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Affiliation(s)
- Chi-Ming Yim
- Department
of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, U.K.
- Tsung
Dao Lee Institute and School of Physics and Astronomy, Shanghai Jiao Tong University, 1 Lisuo Road, Shanghai 201210, China
| | - Michael Allan
- Department
of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, U.K.
| | - Chi Lun Pang
- Department
of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, U.K.
| | - Geoff Thornton
- Department
of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, U.K.
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3
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Sun Y, Wu CR, Wang F, Bi RH, Zhuang YB, Liu S, Chen MS, Zhang KHL, Yan JW, Mao BW, Tian ZQ, Cheng J. Step-induced double-row pattern of interfacial water on rutile TiO 2(110) under electrochemical conditions. Chem Sci 2024; 15:12264-12269. [PMID: 39118606 PMCID: PMC11304521 DOI: 10.1039/d4sc01952k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2024] [Accepted: 05/21/2024] [Indexed: 08/10/2024] Open
Abstract
Metal oxides are promising (photo)electrocatalysts for sustainable energy technologies due to their good activity and abundant resources. Their applications such as photocatalytic water splitting predominantly involve aqueous interfaces under electrochemical conditions, but in situ probing oxide-water interfaces is proven to be extremely challenging. Here, we present an electrochemical scanning tunneling microscopy (EC-STM) study on the rutile TiO2(110)-water interface, and by tuning surface redox chemistry with careful potential control we are able to obtain high quality images of interfacial structures with atomic details. It is interesting to find that the interfacial water exhibits an unexpected double-row pattern that has never been observed. This finding is confirmed by performing a large scale simulation of a stepped interface model enabled by machine learning accelerated molecular dynamics (MLMD) with ab initio accuracy. Furthermore, we show that this pattern is induced by the steps present on the surface, which can propagate across the terraces through interfacial hydrogen bonds. Our work demonstrates that by combining EC-STM and MLMD we can obtain new atomic details of interfacial structures that are valuable to understand the activity of oxides under realistic conditions.
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Affiliation(s)
- Yan Sun
- State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, Xiamen University Xiamen 361005 China
| | - Cheng-Rong Wu
- State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, Xiamen University Xiamen 361005 China
| | - Feng Wang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, Xiamen University Xiamen 361005 China
| | - Rui-Hao Bi
- State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, Xiamen University Xiamen 361005 China
| | - Yong-Bin Zhuang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, Xiamen University Xiamen 361005 China
| | - Shuai Liu
- State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, Xiamen University Xiamen 361005 China
| | - Ming-Shu Chen
- State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, Xiamen University Xiamen 361005 China
| | - Kelvin H-L Zhang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, Xiamen University Xiamen 361005 China
| | - Jia-Wei Yan
- State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, Xiamen University Xiamen 361005 China
| | - Bing-Wei Mao
- State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, Xiamen University Xiamen 361005 China
| | - Zhong-Qun Tian
- State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, Xiamen University Xiamen 361005 China
- Laboratory of AI for Electrochemistry (AI4EC), IKKEM Xiamen 361005 China
| | - Jun Cheng
- State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, Xiamen University Xiamen 361005 China
- Laboratory of AI for Electrochemistry (AI4EC), IKKEM Xiamen 361005 China
- Institute of Artificial Intelligence, Xiamen University Xiamen 361005 China
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4
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Lai Y, Zeng Y, Li F, Chen X, Wang T, Guo Q. Wavelength-Dependent Activity of Oxygen Species in Propane Conversion on Rutile TiO 2(110). J Phys Chem Lett 2024; 15:6943-6951. [PMID: 38940377 DOI: 10.1021/acs.jpclett.4c01035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/29/2024]
Abstract
Photocatalytic oxidative dehydrogenation of propane (C3H8) into propene (C3H6) under mild conditions holds great potential in the chemical industry, but understanding how active species participate in C3H8 conversion remains a significant challenge. Here, the wavelength-dependent activities of bridging oxygen (Ob2-) and the Ti5c-bound oxygen adatom (OTi2-) of model rutile (R) TiO2(110) in C3H8 conversion have been investigated. Under 257 and 343 nm irradiation, hole-trapped OTi- and Ob- can abstract the hydrogen atom of C3H8, forming the CH3CH•CH3 radical and C3H6. However, the rate of C3H8 conversion with hole-trapped Ob- is strongly dependent on the wavelength, primarily producing the C3H7• radical. In the case of hole-trapped OTi-, C3H6 is the main product, which is nearly independent of wavelength. The differences in the wavelength-dependent activity and product selectivity are likely due to dynamic control rather than thermodynamic control. The result provides a deeper understanding of the dynamic processes involved in the conversion of light alkanes in TiO2 photocatalysis.
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Affiliation(s)
- Yuemiao Lai
- Shenzhen Key Laboratory of Energy Chemistry and Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong 518055, P. R. China
| | - Yi Zeng
- Shenzhen Key Laboratory of Energy Chemistry and Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong 518055, P. R. China
| | - Fangliang Li
- Shenzhen Key Laboratory of Energy Chemistry and Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong 518055, P. R. China
| | - Xiao Chen
- Shenzhen Key Laboratory of Energy Chemistry and Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong 518055, P. R. China
- Institute of Advanced Science Facilities, Shenzhen, Guangdong 518107, P. R. China
| | - Tao Wang
- Shenzhen Key Laboratory of Energy Chemistry and Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong 518055, P. R. China
| | - Qing Guo
- Shenzhen Key Laboratory of Energy Chemistry and Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong 518055, P. R. China
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5
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Zhu B, Huang W, Lin H, Feng H, Palotás K, Lv J, Ren Y, Ouyang R, Yang F. Vacancy Ordering in Ultrathin Copper Oxide Films on Cu(111). J Am Chem Soc 2024; 146:15887-15896. [PMID: 38825776 DOI: 10.1021/jacs.4c02424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
Oxide thin films grown on metal surfaces have wide applications in catalysis and beyond owing to their unique surface structures compared to their bulk counterparts. Despite extensive studies, the atomic structures of copper surface oxides on Cu(111), commonly referred to as "44" and "29", have remained elusive. In this work, we demonstrated an approach for the structural determination of oxide surfaces using element-specific scanning tunneling microscopy (STM) imaging enhanced by functionalized tips. This approach enabled us to resolve the atomic structures of "44" and "29" surface oxides, which were further corroborated by noncontact atomic force microscopy (nc-AFM) measurements and Monte Carlo (MC) simulations. The stoichiometry of the "44" and "29" frameworks was identified as Cu23O16 and Cu16O11, respectively. Contrary to the conventional hypothesis, we observed ordered Cu vacancies within the "44" structure manifesting as peanut-shaped cavities in the hexagonal lattice. Similarly, a combination of Cu and O vacancies within the "29" structure leads to bean-shaped cavities within the pentagonal lattice. Our study has thus resolved the decades-long controversy on the atomic structures of "44" and "29" surface oxides, advancing our understanding of copper oxidation processes and introducing a robust framework for the analysis of complex oxide surfaces.
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Affiliation(s)
- Bowen Zhu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Wugen Huang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Haiping Lin
- School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710119, China
| | - Hao Feng
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | | | - Jiayu Lv
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Yihui Ren
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Runhai Ouyang
- Materials Genome Institute, Shanghai University, Shanghai 200444, China
| | - Fan Yang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
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6
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Li J, Wang T, Xia S, Chen W, Ren Z, Sun M, Che L, Yang X, Zhou C. Site-Selective Excitation of Ti 3+ Ions in Rutile TiO 2 via Anisotropic Intra-Atomic 3d → 3d Transition. JACS AU 2024; 4:491-501. [PMID: 38425939 PMCID: PMC10900497 DOI: 10.1021/jacsau.3c00600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 12/06/2023] [Accepted: 01/03/2024] [Indexed: 03/02/2024]
Abstract
Site-selective excitation (SSE), which is usually realized by tuning the wavelength of absorbed light, is an ideal way to study bond-selective chemistry, analyze the crystal structure, investigate protein conformation, etc., eventually leading to active manipulation of desired processes. Herein, SSE has been explored in (110)-, (100)-, and (011)-faced rutile TiO2, a prototypical material in both surface science and photocatalysis fields. Using ultraviolet photoelectron spectroscopy and photon energy-, substrate orientation-, and laser polarization-dependent two-photon photoemission spectroscopy (2PPE), intra-atomic 3d → 3d transition from the split Ti3+ 3d orbitals, i.e., band gap states and excited states at ∼1.00 eV below and ∼2.40 eV above the Fermi level, respectively, has been proven for all of the samples, suggesting that it is a common property of this material. The distinct structure of rutile TiO2 results in the anisotropic 3d → 3d transitions with the transition dipole moment along the long axes ([110] and [11̅0]) of TiO6 blocking units. This anisotropy facilitates the selective excitation of Ti3+ ions in the two types of TiO6, which cannot be realized by conventional wavelength tuning, via polarization alignment of the excitation source. Discovery in this work builds the foundation for future investigation of site-selective photophysical and photochemical processes and eventually possible active manipulation in this material at the atomic level.
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Affiliation(s)
- Jialong Li
- Department
of Physics, School of Science, Dalian Maritime
University, 116026 Dalian, China
- State
Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 116023 Dalian, China
| | - Tianjun Wang
- State
Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 116023 Dalian, China
| | - Shucai Xia
- State
Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 116023 Dalian, China
| | - Wei Chen
- State
Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 116023 Dalian, China
- University
of Chinese Academy of Sciences, No.19A Yuquan Road, Shijingshan District, 100049 Beijing, China
| | - Zefeng Ren
- State
Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 116023 Dalian, China
| | - Min Sun
- Department
of Physics, School of Science, Dalian Maritime
University, 116026 Dalian, China
| | - Li Che
- Department
of Physics, School of Science, Dalian Maritime
University, 116026 Dalian, China
| | - Xueming Yang
- State
Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 116023 Dalian, China
- Department
of Chemistry, Southern University of Science
and Technology, 1088
Xueyuan Road, 518055 Shenzhen, Guangdong, China
| | - Chuanyao Zhou
- State
Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 116023 Dalian, China
- University
of Chinese Academy of Sciences, No.19A Yuquan Road, Shijingshan District, 100049 Beijing, China
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7
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Qiao X, Qiu Y, Xin J, Chen D, Ma Z, Corkett AJ, Cai G, Cai G, Qu S, Wang Y, Zhu Z, Gao Y, Wang Z, Dronskowski R, Li G, Sun J. Synthesis, crystal structures and semiconducting properties of new hexacyanidometallates. Dalton Trans 2023; 52:3971-3980. [PMID: 36880672 DOI: 10.1039/d3dt00384a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2023]
Abstract
We describe the synthesis, crystal structure and semiconducting properties of a number of hexacyanidometallates with the formula A2[MFe(CN)6]·xH2O (A = Na, K; M = Mg, Ca, Sr and Ba). All crystal structures were studied via single-crystal or powder X-ray diffraction. The unexpectedly low-symmetric structures in these ferrocyanides are described and contrasted with analogous transition-metal compounds which have been reported to be strictly or nearly cubic. The amount of crystal water in the structure for powder samples was determined by the thermogravimetric analysis (TGA), supported by IR and Raman spectroscopy. Electronic-structure calculations of K2[MgFe(CN)6] and K2[CaFe(CN)6] are compared with experimental UV-Vis measurements. The large band gaps by advanced theory indicate that the smaller experimental band gaps are due to surface effects of impurity states. Mott-Schottky curves of K2[MgFe(CN)6], K2[CaFe(CN)6] and K2[BaFe(CN)6]·3H2O exhibit positive slopes, which characterizes these compounds as n-type semiconductors.
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Affiliation(s)
- Xianji Qiao
- College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, China.
| | - Yi Qiu
- College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, China.
| | - Junjie Xin
- College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, China.
| | - Da Chen
- Chair of Solid-State and Quantum Chemistry, Institute of Inorganic Chemistry, RWTH Aachen University, Aachen 52056, Germany. .,Hoffmann Institute of Advanced Materials, Shenzhen Polytechnic, 7098 Liuxian Boulevard, Nanshan District, Shenzhen 518055, China
| | - Zili Ma
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, 230026 Hefei, Anhui, China
| | - Alex J Corkett
- Hoffmann Institute of Advanced Materials, Shenzhen Polytechnic, 7098 Liuxian Boulevard, Nanshan District, Shenzhen 518055, China
| | - Guohong Cai
- College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, China.
| | - Guanqun Cai
- College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, China.
| | - Shangqing Qu
- College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, China.
| | - YuChao Wang
- College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, China. .,College of Chemistry and Life Science, Changchun University of Technology, Changchun 130012, China
| | - Zhenyu Zhu
- College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, China.
| | - Yiman Gao
- College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, China.
| | - Zhigang Wang
- Hanon Advanced Technology Group Co., Ltd., HanYuJinGu Business Center, No.7000 Jingshi Road, Hi-Tech Development Zone, Jinan 250100, China
| | - Richard Dronskowski
- Chair of Solid-State and Quantum Chemistry, Institute of Inorganic Chemistry, RWTH Aachen University, Aachen 52056, Germany. .,Hoffmann Institute of Advanced Materials, Shenzhen Polytechnic, 7098 Liuxian Boulevard, Nanshan District, Shenzhen 518055, China
| | - Guobao Li
- College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, China.
| | - Junliang Sun
- College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, China.
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8
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Ma X, Shi Y, Liu J, Li X, Cui X, Tan S, Zhao J, Wang B. Hydrogen-Bond Network Promotes Water Splitting on the TiO 2 Surface. J Am Chem Soc 2022; 144:13565-13573. [DOI: 10.1021/jacs.2c03690] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Xiaochuan Ma
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yongliang Shi
- Center for Spintronics and Quantum Systems, State Key Laboratory for Mechanical Behavior of Materials, School of Materials Science and Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China
| | - Jianyi Liu
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Xintong Li
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Xuefeng Cui
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Shijing Tan
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Jin Zhao
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- ICQD/Hefei National Research Center for Physical Sciences at the Microscale, and CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Bing Wang
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
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9
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Schio L, Forrer D, Casarin M, Goldoni A, Rogero C, Vittadini A, Floreano L. On surface chemical reactions of free-base and titanyl porphyrins with r-TiO 2(110): a unified picture. Phys Chem Chem Phys 2022; 24:12719-12744. [PMID: 35583960 DOI: 10.1039/d2cp01073a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this Perspective we present a comprehensive study of the multiple reaction products of metal-free porphyrins (2H-Ps) in contact with the rutile TiO2(110) surface. In the absence of peripheral functionalization with specific linkers, the porphyrin adsorption is driven by the coordination of the two pyrrolic nitrogen atoms of the macrocycle to two consecutive oxygen atoms of the protruding Obr rows via hydrogen bonding. This chemical interaction favours the iminic nitrogen uptake of hydrogen from near surface layers at room temperature, thus yielding a stable acidic porphyrin (4H-P). In addition, a mild annealing (∼100 °C) triggers the incorporation of a Ti atom in the porphyrin macrocycle (self-metalation). We recently demonstrated that such a low temperature reaction is driven by a Lewis base iminic attack, which lowers the energy barriers for the outdiffusion of Ti interstitial atoms (Tiint) [Kremer et al., Appl. Surf. Sci., 2021, 564, 150403]. In the monolayer (ML) range, the porphyrin adsorption site, corresponding to a TiO-TPP configuration, is extremely stable and tetraphenyl-porphyrins (TPPs) may even undergo conformational distortion (flattening) by partial cyclo-dehydrogenation, while remaining anchored to the O rows up to 450 °C [Lovat et al., Nanoscale, 2017, 9, 11694]. Here we show that, upon self-metalation, isolated molecules at low coverage may jump atop the rows of five-fold coordinated Ti atoms (Ti5f). This configuration is associated with the formation of a new coordination complex, Ti-O-Ti5f, as determined by comparison with the deposition of pristine titanyl-porphyrin (TiO-TPP) molecules. The newly established Ti-O-Ti5f anchoring configuration is found to be stable also beyond the TPP flattening reaction. The anchoring of TiO-TPP to the Ti5f rows is, however, susceptible to the cross-talk between phenyls of adjacent molecules, which ultimately drives the TiO-TPP temperature evolution in the ML range along the same pathway followed by 2H-TPP.
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Affiliation(s)
- Luca Schio
- CNR-IOM, Laboratorio TASC, Basovizza S.S. 14, Km 163.5, I-34149 Trieste, Italy.
| | - Daniel Forrer
- CNR-ICMATE and INSTM, via Marzolo 1, I-35131 Padova, Italy.
| | - Maurizio Casarin
- CNR-ICMATE and INSTM, via Marzolo 1, I-35131 Padova, Italy. .,Dipartimento di Scienze Chimiche, Università di Padova, via Marzolo 1, I-35131 Padova, Italy
| | - Andrea Goldoni
- Elettra-Sincrotrone Trieste S.C.p.A., Basovizza SS-14, Km 163.5, 34149 Trieste, Italy
| | - Celia Rogero
- Materials Physics Center MPC, Centro de Física de Materiales (CSIC-UPV/EHU) and Donostia International Physics Center (DIPC), E-20018 San Sebastian, Spain
| | | | - Luca Floreano
- CNR-IOM, Laboratorio TASC, Basovizza S.S. 14, Km 163.5, I-34149 Trieste, Italy.
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10
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Abstract
A pure Ti target in Ar/O2 gas mixture was used to synthesize Ti3Ox thin film on a glass substrate by Reactive High-Power Impulse Magnetron Sputtering (HiPIMS) under different sputtering power (2 and 2.5 kW). The influence of HiPIMS parameters on thin films’ structural, morphological, chemical composition, optical and photocatalytic, and antibacterial properties was investigated. In this study, Ti3Ox thin films can be synthesized using the HiPIMS method without the post-annealing process. Two co-existence phases (hexagonal Ti3O and base-centered monoclinic Ti3O5 phases) existed on the Ti3Ox films. It is found that the peak intensity of (006) Ti3O hexagonal slightly increased as the sputtering power increased from 2 to 2.5 kW. The Ti3Ox thin-film bandgap values were 3.36 and 3.50 eV for 2 and 2.5 kW, respectively. The Ti3Ox films deposited at 2.5 kW showed good photocatalytic activity under UV light irradiation, with a higher methylene blue dye degradation rate than TiO2 thin films. The antibacterial study on Ti3Ox thin films exhibited a high inhibition percentage against E. coli and S. aureus. This study demonstrates that Ti3Ox thin films can promote high photocatalytic and antibacterial activity.
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11
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Miyazaki M, Sugawara Y, Li YJ. Charge Behavior of Terminal Hydroxyl on Rutile TiO 2(110). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:10588-10593. [PMID: 34433262 DOI: 10.1021/acs.langmuir.1c01845] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Titanium dioxide (TiO2) is of considerable interest as a photocatalyst and a catalyst support. Surface hydroxyl groups (OH) are the most common adsorbates on the TiO2 surface and are believed to play crucial roles in their applications. Although the characteristics of bridging hydroxyl (OHbr) have been well understood, the adsorption structure and charged states of terminal hydroxyl (OHt) have not yet been experimentally elucidated at an atomic scale. In this study, we have investigated an isolated OHt on the rutile TiO2(110) surface by atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM). We found that OHt is in a negatively charged state. The unique characteristic of OHt is different from that of OHbr and involves the amphoterism and diversity of catalytic reactions of TiO2.
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Affiliation(s)
- Masato Miyazaki
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yasuhiro Sugawara
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yan Jun Li
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
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12
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The Phase Evolution and Photocatalytic Properties of a Ti-TiO2 Bilayer Thin Film Prepared Using Thermal Oxidation. COATINGS 2021. [DOI: 10.3390/coatings11070808] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Ti-TiO2 bilayer thin films were successfully prepared onto a glass substrate using magnetron sputtering with different TiO2 bottom layer conditions. These represent a lack of (as-deposited) and full oxygen content (annealed). Single-layer Ti was additionally used as a control. The influence of oxygen diffusion phenomena of the bottom layer of TiO2 to the upper layer of Ti thin films at different oxidation temperatures on structural, optical, and photocatalytic performance was investigated. X-ray diffraction (XRD) results confirmed that the crystalline phases coexisting on thin-film samples oxidized at 450 °C were TiO, TiO1.4, (bilayer, as-deposited TiO2), anatase (bilayer, annealed TiO2), and rutile (single and bilayer). This finding showed that the film’s phase structure evolution is significantly affected by oxygen diffusion from the bottom layer. Further increasing the thermal oxidation temperature caused a notable decline in the amorphous zone in bilayer thin films based on TEM analysis. Bilayer thin films lead to higher degradation of methylene blue under UV light radiation (63%) than single-layer films (45%) oxidized at 450 °C. High photocatalytic activity performance was found in the bilayer annealed TiO2-Ti thin-film sample. This study demonstrates that the bilayer modification strategy promotes the oxygen-induced bottom layer of TiO2 bilayer thin films.
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13
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Tang DF, Chen X, Guo Q, Yang WS. Effects of surface defects on adsorption of CO and methyl groups on rutile TiO2(110). CHINESE J CHEM PHYS 2021. [DOI: 10.1063/1674-0068/cjcp2012221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Deng-fang Tang
- Hangzhou Institute of Advanced studies, Zhejiang Normal University, Hangzhou 311231, China
| | - Xiao Chen
- Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055, China
| | - Qing Guo
- Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055, China
| | - Wen-shao Yang
- Hangzhou Institute of Advanced studies, Zhejiang Normal University, Hangzhou 311231, China
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14
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Janas K, Boniewska-Bernacka E, Dyrda G, Słota R. Porphyrin and phthalocyanine photosensitizers designed for targeted photodynamic therapy of colorectal cancer. Bioorg Med Chem 2020; 30:115926. [PMID: 33341498 DOI: 10.1016/j.bmc.2020.115926] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 12/01/2020] [Accepted: 12/03/2020] [Indexed: 11/27/2022]
Abstract
Colorectal cancer is of particular concern due to its high mortality rate count. Recent investigations on targeted phototherapy involving novel photosensitizers and drug-delivery systems have provided promising results and realistic prospects for a successful medical treatment. New research trends have been focused particularly on development of advanced molecular systems offering effective photoactive species which could be selectively delivered directly into the affected cells. Porphyrins and phthalocyanines have been considered extremely attractive for this purpose due to their molecular versatility, excellent photochemical properties and multifunctional nature. In this review it has been demonstrated that such macrocyclic compounds may effectively contribute to the inhibition of the growth of colon cancer cells and eventually to their photonecrosis. Purposely designed and tailored porphyrin and phthalocyanine derivatives in combination with smart drug-carriers have proved suitable for photodynamic therapy (PDT) and related antitumor treatments. This survey comprises a choice of potentially applicable ideas developed since 2010 involving 9 different tumor cell lines and featuring 32 photosensitizers.
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Affiliation(s)
- Katarzyna Janas
- Institute of Chemistry, University of Opole, ul. Oleska 48, 45-052 Opole, Poland.
| | - Ewa Boniewska-Bernacka
- Institute of Medical Sciences, University of Opole, ul. Oleska 48, 45-052 Opole, Poland.
| | - Gabriela Dyrda
- Institute of Chemistry, University of Opole, ul. Oleska 48, 45-052 Opole, Poland.
| | - Rudolf Słota
- Institute of Chemistry, University of Opole, ul. Oleska 48, 45-052 Opole, Poland.
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15
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Deskins NA, Kimmel GA, Petrik NG. Observation of Molecular Hydrogen Produced from Bridging Hydroxyls on Anatase TiO 2(101). J Phys Chem Lett 2020; 11:9289-9297. [PMID: 33090788 DOI: 10.1021/acs.jpclett.0c02735] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Anatase TiO2 is used extensively in a wide range of catalytic and photocatalytic processes and is a promising catalyst for hydrogen production. Here, we show that molecular hydrogen was produced from bridging hydroxyls (HOb) on the (101) surface of single-crystal anatase (TiO2(101)). This stands in contrast to rutile TiO2(110), where HOb pairs react to form H2O. Electron bombardment at 30 K produced bridging oxygen vacancies in the surface. Deuterated bridging hydroxyls (DOb) were subsequently formed via dissociation of adsorbed D2O and confirmed by infrared reflection-absorption spectroscopy. During temperature-programmed desorption (TPD) spectroscopy, D2 desorption was observed at 520 K. Density functional theory calculations show that both H2 and H2O production from HOb are endothermic at 0 K on TiO2(101), but H2 (H2O) desorption is entropically driven above 230 K (800 K). The calculated activation barrier for H2 desorption is 1.40 eV, which is similar to the desorption energy obtained from analysis of the D2 TPD spectra. The H2 desorption likely proceeds in two steps: H atom diffusion on the surface and then recombination.
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Affiliation(s)
- N Aaron Deskins
- Department of Chemical Engineering, Worcester Polytechnic Institute, 100 Institute Road, Worcester, Massachusetts 01609, United States
| | - Greg A Kimmel
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States
| | - Nikolay G Petrik
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States
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16
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Wen HF, Sugawara Y, Li YJ. Multi-Channel Exploration of O Adatom on TiO 2(110) Surface by Scanning Probe Microscopy. NANOMATERIALS 2020; 10:nano10081506. [PMID: 32751956 PMCID: PMC7466602 DOI: 10.3390/nano10081506] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 07/22/2020] [Accepted: 07/29/2020] [Indexed: 01/28/2023]
Abstract
We studied the O2 dissociated state under the different O2 exposed temperatures with atomic resolution by scanning probe microscopy (SPM) and imaged the O adatom by simultaneous atomic force microscopy (AFM)/scanning tunneling microscopy (STM). The effect of AFM operation mode on O adatom contrast was investigated, and the interaction of O adatom and the subsurface defect was observed by AFM/STM. Multi-channel exploration was performed to investigate the charge transfer between the adsorbed O and the TiO2(110) by obtaining the frequency shift, tunneling current and local contact potential difference at an atomic scale. The tunneling current image showed the difference of the tunneling possibility on the single O adatom and paired O adatoms, and the local contact potential difference distribution of the O-TiO2(110) surface institutively revealed the charge transfer from TiO2(110) surface to O adatom. The experimental results are expected to be helpful in investigating surface/interface properties by SPM.
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Affiliation(s)
- Huan Fei Wen
- Key Laboratory of Instrumentation Science and Dynamic Measurement, School of Instrument and Electronics, North University of China, Taiyuan 030051, China; (H.F.W.); (Y.S.)
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yasuhiro Sugawara
- Key Laboratory of Instrumentation Science and Dynamic Measurement, School of Instrument and Electronics, North University of China, Taiyuan 030051, China; (H.F.W.); (Y.S.)
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yan Jun Li
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
- Correspondence:
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17
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Pham TD, Deskins NA. Efficient Method for Modeling Polarons Using Electronic Structure Methods. J Chem Theory Comput 2020; 16:5264-5278. [DOI: 10.1021/acs.jctc.0c00374] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Thang Duc Pham
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - N. Aaron Deskins
- Department of Chemical Engineering, Worcester Polytechnic Institute, Worcester, Massachusetts 01609, United States
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18
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Guo C, Meng X, Fu H, Wang Q, Wang H, Tian Y, Peng J, Ma R, Weng Y, Meng S, Wang E, Jiang Y. Probing Nonequilibrium Dynamics of Photoexcited Polarons on a Metal-Oxide Surface with Atomic Precision. PHYSICAL REVIEW LETTERS 2020; 124:206801. [PMID: 32501065 DOI: 10.1103/physrevlett.124.206801] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2019] [Revised: 01/26/2020] [Accepted: 04/09/2020] [Indexed: 06/11/2023]
Abstract
Understanding the nonequilibrium dynamics of photoexcited polarons at the atomic scale is of great importance for improving the performance of photocatalytic and solar-energy materials. Using a pulsed-laser-combined scanning tunneling microscopy and spectroscopy, here we succeeded in resolving the relaxation dynamics of single polarons bound to oxygen vacancies on the surface of a prototypical photocatalyst, rutile TiO_{2}(110). The visible-light excitation of the defect-derived polarons depletes the polaron states and leads to delocalized free electrons in the conduction band, which is further corroborated by ab initio calculations. We found that the trapping time of polarons becomes considerably shorter when the polaron is bound to two surface oxygen vacancies than that to one. In contrast, the lifetime of photogenerated free electrons is insensitive to the atomic-scale distribution of the defects but correlated with the averaged defect density within a nanometer-sized area. Those results shed new light on the photocatalytically active sites at the metal-oxide surface.
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Affiliation(s)
- Chaoyu Guo
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
- Physical Science Laboratory, Huairou National Comprehensive Science Centre, Beijing 101400, People's Republic of China
| | - Xiangzhi Meng
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
| | - Huixia Fu
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Qin Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
| | - Huimin Wang
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Ye Tian
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
| | - Jinbo Peng
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
| | - Runze Ma
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
| | - Yuxiang Weng
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Sheng Meng
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, People's Republic of China
| | - Enge Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, People's Republic of China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Ying Jiang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, People's Republic of China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
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19
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Wu L, Fu C, Huang W. Surface chemistry of TiO 2 connecting thermal catalysis and photocatalysis. Phys Chem Chem Phys 2020; 22:9875-9909. [PMID: 32363360 DOI: 10.1039/c9cp07001j] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Chemical reactions catalyzed under heterogeneous conditions have recently expanded rapidly from traditional thermal catalysis to photocatalysis due to the rising concerns about sustainable development of energy and the environment. Adsorption of reactants on catalyst surfaces, subsequent surface reactions, and desorption of products from catalyst surfaces occur in both thermal catalysis and photocatalysis. TiO2 catalysts are widely used in thermal catalytic and photocatalytic reactions. Herein we review recent progress in surface chemistry, thermal catalysis and photocatalysis of TiO2 model catalysts from single crystals to nanocrystals with the aim of examining if the surface chemistry of TiO2 can bridge the fundamental understanding between thermal catalysis and photocatalysis. Following a brief introduction, the structures of major facets exposed on TiO2 catalysts, including surface reconstructions and defects, as well as the electronic structure and charge properties, are firstly summarized; then the recent progress in adsorption, thermal chemistry and photochemistry of small molecules on TiO2 single crystals and nanocrystals is comprehensively reviewed, focusing on manifesting the structure-(photo)activity relations and the commonalities/differences between thermal catalysis and photocatalysis; and finally concluding remarks and perspectives are given.
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Affiliation(s)
- Longxia Wu
- Hefei National Laboratory for Physical Sciences at the Microscale, Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes and Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, P. R. China.
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20
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Dispersion of Defects in TiO2 Semiconductor: Oxygen Vacancies in the Bulk and Surface of Rutile and Anatase. Catalysts 2020. [DOI: 10.3390/catal10040397] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Oxygen deficiency (O-vacancy) contributes to the photoefficiency of TiO2 semiconductors by generating electron rich active sites. In this paper, the dispersion of O-vacancies in both bulk and surface of anatase and rutile phases was computationally investigated. The results showed that the O-vacancies dispersed in single- and double-cluster forms in the anatase and rutile phases, respectively, in both bulk and surface. The distribution of the O-vacancies was (roughly) homogeneous in anatase, and heterogenous in rutile bulk. The O-vacancy formation energy, width of defect band, and charge distribution indicated the overlap of the defect states in the rutile phase and thus eased the formation of clusters. Removal of the first and the second oxygen atoms from the rutile surface took less energy than the anatase one, which resulted in a higher deficiency concentration on the rutile surface. However, these deficiencies formed one active site per unit cell of rutile. On the other hand, the first O-vacancy formed on the surface and the second one formed in the subsurface of anatase (per unit cell). Supported by previous studies, we argue that this distribution of O-vacancies in anatase (surface and subsurface) could potentially create more active sites on its surface.
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21
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Katsube D, Ojima S, Inami E, Abe M. Atomic-resolution imaging of rutile TiO 2(110)-(1 × 2) reconstructed surface by non-contact atomic force microscopy. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2020; 11:443-449. [PMID: 32215231 PMCID: PMC7082707 DOI: 10.3762/bjnano.11.35] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 02/22/2020] [Indexed: 06/10/2023]
Abstract
The structure of the rutile TiO2(110)-(1 × 2) reconstructed surface is a phase induced by oxygen reduction. There is ongoing debate about the (1 × 2) reconstruction, because it cannot be clarified whether the (1 × 2) structure is formed over a wide area or only locally using macroscopic analysis methods such as diffraction. We used non-contact atomic force microscopy, scanning tunneling microscopy, and low-energy electron diffraction at room temperature to characterize the surface. Ti2O3 rows appeared as bright spots in both NC-AFM and STM images observed in the same area. High-resolution NC-AFM images revealed that the rutile TiO2(110)-(1 × 2) reconstructed surface is composed of two domains with different types of asymmetric rows.
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Affiliation(s)
- Daiki Katsube
- Graduate School of Engineering, Nagaoka University of Technology, 1603-1 Kamitomiokamachi, Nagaoka, Niigata 940-2188, Japan
- Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
| | - Shoki Ojima
- Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
| | - Eiichi Inami
- School of Systems Engineering, Kochi University of Technology, 185 Miyanokuchi, Tosayamada, Kami, Kochi 782-8502, Japan
| | - Masayuki Abe
- Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
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22
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Tan S, Feng H, Zheng Q, Cui X, Zhao J, Luo Y, Yang J, Wang B, Hou JG. Interfacial Hydrogen-Bonding Dynamics in Surface-Facilitated Dehydrogenation of Water on TiO 2(110). J Am Chem Soc 2020; 142:826-834. [PMID: 31842546 DOI: 10.1021/jacs.9b09132] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Molecular-level understanding of the dehydrogenation of interfacial water molecules on metal oxides and their interactive nature relies on the ability to track the motion of light and small hydrogen atoms, which is known to be difficult. Here, we report precise measurements of the surface-facilitated water dehydrogenation process at terminal Ti sites of TiO2(110) using scanning tunneling microscopy. Our measured hydrogen-bond dynamics of H2O and D2O reveal that the vibrational and electronic excitations dominate the sequential transfer of two H (D) atoms from a H2O (D2O) molecule to adjacent surface oxygen sites, manifesting the active participation of the oxide surface in the dehydrogenation processes. Our results show that, at the stoichiometric Ti5c sites, individual H2O molecules are energetically less stable than the dissociative form, where a barrier is expected to be as small as approximately 70-120 meV on the basis of our experimental and theoretical results. Moreover, our results reveal that interfacial hydrogen bonds can effectively assist H atom transfer and exchange across the surface. The revealed quantitative hydrogen-bond dynamics provide a new atomistic mechanism for water interactions on metal oxides in general.
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Affiliation(s)
- Shijing Tan
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information & Quantum Physics (CAS) , University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - Hao Feng
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information & Quantum Physics (CAS) , University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - Qijing Zheng
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information & Quantum Physics (CAS) , University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - Xuefeng Cui
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information & Quantum Physics (CAS) , University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - Jin Zhao
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information & Quantum Physics (CAS) , University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - Yi Luo
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information & Quantum Physics (CAS) , University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - Jinlong Yang
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information & Quantum Physics (CAS) , University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - Bing Wang
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information & Quantum Physics (CAS) , University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - J G Hou
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information & Quantum Physics (CAS) , University of Science and Technology of China , Hefei , Anhui 230026 , China
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23
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Mellor A, Wilson A, Pang CL, Yim CM, Maccherozzi F, Dhesi SS, Muryn CA, Idriss H, Thornton G. Photoemission core level binding energies from multiple sized nanoparticles on the same support: TiO 2(110)/Au. J Chem Phys 2020; 152:024709. [PMID: 31941300 DOI: 10.1063/1.5135760] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
A novel method of measuring the core level binding energies of multiple sized nanoparticles on the same substrate is demonstrated using the early stage of Au nanoparticle growth on reduced r-TiO2(110). This method employed in situ scanning tunneling microscopy (STM) and microfocused X-ray photoemission spectroscopy. An STM tip-shadowing method was used to synthesize patterned areas of Au nanoparticles on the substrate with different coverages and sizes. Patterns were identified and imaged using a UV photoelectron emission microscope. The Au 4f core level binding energies of the nanoparticles were investigated as a function of Au nanoparticle coverage and size. A combination of initial and final state effects modifies the binding energies of the Au 4f core levels as the nanoparticle size changes. When single Au atoms and Au3 clusters are present, the Au 4f7/2 binding energy, 84.42 eV, is similar to that observed at a high coverage (1.8 monolayer equivalent), resulting from a cancellation of initial and final state effects. As the coverage is increased, there is a decrease in binding energy, which then increases at a higher coverage to 84.39 eV. These results are consistent with a Volmer-Weber nucleation-growth model of Au nanoparticles at oxygen vacancies, resulting in electron transfer to the nanoparticles.
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Affiliation(s)
- Andrew Mellor
- Department of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Axel Wilson
- Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE, United Kingdom
| | - Chi L Pang
- Department of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Chi M Yim
- Department of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Francesco Maccherozzi
- Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE, United Kingdom
| | - Sarnjeet S Dhesi
- Diamond Light Source, Harwell Science and Innovation Campus, Oxfordshire OX11 0DE, United Kingdom
| | - Christopher A Muryn
- School of Chemistry and Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Hicham Idriss
- Department of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Geoff Thornton
- Department of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
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24
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Glass D, Cortés E, Ben‐Jaber S, Brick T, Peveler WJ, Blackman CS, Howle CR, Quesada‐Cabrera R, Parkin IP, Maier SA. Dynamics of Photo-Induced Surface Oxygen Vacancies in Metal-Oxide Semiconductors Studied Under Ambient Conditions. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2019; 6:1901841. [PMID: 31763155 PMCID: PMC6864511 DOI: 10.1002/advs.201901841] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 09/05/2019] [Indexed: 05/23/2023]
Abstract
Surface-enhanced Raman spectroscopy (SERS) is a powerful analytical technique commonly used in the detection of traces of organic molecules. The mechanism of SERS is of a dual nature, with Raman scattering enhancements due to a combination of electromagnetic (EM) and chemical contributions. In conventional SERS, the EM component is largely responsible for the enhancement, with the chemical contribution playing a less significant role. An alternative technique, called photo-induced enhanced Raman spectroscopy (PIERS) has been recently developed, using a photo-activated semiconductor substrate to give additional chemical enhancement of Raman bands over traditional SERS. This enhancement is assigned to surface oxygen vacancies (V o) formed upon pre-irradiation of the substrate. In this work, the exceptional chemical contribution in PIERS allows for the evaluation of atomic V o dynamics in metal oxide surfaces. This technique is applied to study the formation and healing rates of surface-active V o in archetypical metal-oxide semiconductors, namely, TiO2, WO3, and ZnO. Contrary to conventional analytical tools, PIERS provides intuitive and valuable information about surface stability of atomic defects at ambient pressure and under operando conditions, which has important implications in a wide range of applications including catalysis and energy storage materials.
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Affiliation(s)
- Daniel Glass
- The Blackett LaboratoryDepartment of PhysicsImperial College LondonLondonSW7 2AZUK
- Department of ChemistryUniversity College London20 Gordon StLondonWC1H 0AJUK
| | - Emiliano Cortés
- The Blackett LaboratoryDepartment of PhysicsImperial College LondonLondonSW7 2AZUK
- Chair in Hybrid NanosystemsNanoinsitute MunichFaculty of PhysicsLudwig Maximilians Universität München80539MünchenGermany
| | - Sultan Ben‐Jaber
- Department of ChemistryUniversity College London20 Gordon StLondonWC1H 0AJUK
- Department of Forensics ScienceKing Fahad Security CollageRiyadh11461Saudi Arabia
| | - Thomas Brick
- The Blackett LaboratoryDepartment of PhysicsImperial College LondonLondonSW7 2AZUK
| | - William J. Peveler
- Department of ChemistryUniversity College London20 Gordon StLondonWC1H 0AJUK
- School of ChemistryJoseph Black BuildingUniversity of GlasgowGlasgowG12 8QQUK
| | | | | | | | - Ivan P. Parkin
- Department of ChemistryUniversity College London20 Gordon StLondonWC1H 0AJUK
| | - Stefan A. Maier
- The Blackett LaboratoryDepartment of PhysicsImperial College LondonLondonSW7 2AZUK
- Chair in Hybrid NanosystemsNanoinsitute MunichFaculty of PhysicsLudwig Maximilians Universität München80539MünchenGermany
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25
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Guo Q, Ma Z, Zhou C, Ren Z, Yang X. Single Molecule Photocatalysis on TiO2 Surfaces. Chem Rev 2019; 119:11020-11041. [DOI: 10.1021/acs.chemrev.9b00226] [Citation(s) in RCA: 129] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Qing Guo
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, 457 Zhongshan Road, Dalian, Liaoning 116023, P. R. China
- Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong 518055, P. R. China
| | - Zhibo Ma
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, 457 Zhongshan Road, Dalian, Liaoning 116023, P. R. China
| | - Chuanyao Zhou
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, 457 Zhongshan Road, Dalian, Liaoning 116023, P. R. China
| | - Zefeng Ren
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, 457 Zhongshan Road, Dalian, Liaoning 116023, P. R. China
| | - Xueming Yang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, 457 Zhongshan Road, Dalian, Liaoning 116023, P. R. China
- Department of Chemistry, Southern University of Science and Technology, Shenzhen, Guangdong 518055, P. R. China
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26
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Dong S, Li B, Cui X, Tan S, Wang B. Photoresponses of Supported Au Single Atoms on TiO 2(110) through the Metal-Induced Gap States. J Phys Chem Lett 2019; 10:4683-4691. [PMID: 31364858 DOI: 10.1021/acs.jpclett.9b01527] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
When a metal single-atom (SA) catalyst is supported on a semiconducting photocatalyst, the charge transfer of the photoexcited carriers to metal SAs can provide a synergetic activity for the co-catalysts. Here, we report the interfacial electronic coupling of the Au SAs on the TiO2(110) surface using scanning tunneling microscopy/spectroscopy, in combination with first-principles calculations. Distinct energy and spatial distributions of the metal-induced gap states (MIGSs) are experimentally revealed for the Au SAs adsorbed at the terminal Ti sites and the oxygen vacancies. The localized MIGS below the Fermi level provides a dedicated channel for the transfer of a photoexcited hole from the TiO2 substrate to the adsorbed Au SAs. The hole can weaken the Ti-Au bonding and activate the diffusion of Au SAs. Our results shed light on combining the advantages of photocatalysis and metal SA catalysis using a co-catalyst, which is promising to promote chemical reactions at low temperatures.
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Affiliation(s)
- Shihui Dong
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information & Quantum Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - Bin Li
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information & Quantum Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - Xuefeng Cui
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information & Quantum Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - Shijing Tan
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information & Quantum Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
| | - Bing Wang
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information & Quantum Physics , University of Science and Technology of China , Hefei , Anhui 230026 , China
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27
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Ma ZM, Wu XS, Zheng DD, Wei JY, Xie YN, Shi YB, Huang K, Zhang XM, Liu J. Well-Aligned TiO 2 Nanotube Arrays with Ag Nanoparticles for Highly Efficient Detection of Fe 3+ Ion. NANOSCALE RESEARCH LETTERS 2019; 14:49. [PMID: 30725240 PMCID: PMC6365581 DOI: 10.1186/s11671-019-2883-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 01/28/2019] [Indexed: 06/09/2023]
Abstract
Nowadays, determination of the iron ions with high sensitivity and selectivity with novel methods becomes a matter of urgency for monitoring healthy body and environment. In this paper, for the first time, we present a set of high-performance TiO2 nanotube arrays which are quite sensitive to iron ions. Firstly, the anodic oxidation method was adopted to prepare ordered TiO2 nanotube arrays, followed by functionalized Ag nanoparticle deposition with the enhancement ability in iron ion sensing. Besides, the spectrum of the TiO2 nanotube with/without the Ag nanoparticles was analyzed with an X-ray photoelectron spectrometer, which shows that Ag nanoparticles can effectively reduce the recombination rate of electrons and holes, and increase the conductivity and the charge transfer rate of the electrodes. Further, when functionalized Ag nanoparticles on well-ordered TiO2 nanotube arrays were used, iron ion sensing performed with the anodic stripping voltammetry method was investigated to validate the great potential of TiO2 nanotube arrays with a sensitivity of approximately 30 μA/ug/L in becoming Fe3+ sensors. This method creates new possibilities for developing sensors for monitoring of Fe3+ in biological samples without any sample pretreatment procedure.
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Affiliation(s)
- Zong-Min Ma
- Science and Technology on Electronic Test & Measurement Laboratory, North University of China, No.3, Xue Yuan Road, Taiyuan, 030051 Shanxi China
- School of Instrument and Electronics, North University of China, Taiyuan, 030051 China
| | - Xing-Sheng Wu
- Science and Technology on Electronic Test & Measurement Laboratory, North University of China, No.3, Xue Yuan Road, Taiyuan, 030051 Shanxi China
- School of Instrument and Electronics, North University of China, Taiyuan, 030051 China
| | - Dou-Dou Zheng
- Science and Technology on Electronic Test & Measurement Laboratory, North University of China, No.3, Xue Yuan Road, Taiyuan, 030051 Shanxi China
- School of Instrument and Electronics, North University of China, Taiyuan, 030051 China
| | - Jiu-Yan Wei
- Science and Technology on Electronic Test & Measurement Laboratory, North University of China, No.3, Xue Yuan Road, Taiyuan, 030051 Shanxi China
- School of Instrument and Electronics, North University of China, Taiyuan, 030051 China
| | - Yan-Na Xie
- Science and Technology on Electronic Test & Measurement Laboratory, North University of China, No.3, Xue Yuan Road, Taiyuan, 030051 Shanxi China
- School of Instrument and Electronics, North University of China, Taiyuan, 030051 China
| | - Yun-Bo Shi
- Science and Technology on Electronic Test & Measurement Laboratory, North University of China, No.3, Xue Yuan Road, Taiyuan, 030051 Shanxi China
- School of Instrument and Electronics, North University of China, Taiyuan, 030051 China
| | - Kun Huang
- School of Instrument and Electronics, North University of China, Taiyuan, 030051 China
| | - Xiao-Ming Zhang
- Science and Technology on Electronic Test & Measurement Laboratory, North University of China, No.3, Xue Yuan Road, Taiyuan, 030051 Shanxi China
- School of Instrument and Electronics, North University of China, Taiyuan, 030051 China
| | - Jun Liu
- Science and Technology on Electronic Test & Measurement Laboratory, North University of China, No.3, Xue Yuan Road, Taiyuan, 030051 Shanxi China
- School of Instrument and Electronics, North University of China, Taiyuan, 030051 China
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28
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Wen HF, Miyazaki M, Zhang Q, Adachi Y, Li YJ, Sugawara Y. Direct observation of atomic step edges on the rutile TiO 2(110)-(1 × 1) surface using atomic force microscopy. Phys Chem Chem Phys 2018; 20:28331-28337. [PMID: 30398504 DOI: 10.1039/c8cp06156d] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Clarifying the atomic configuration of step edges on a rutile TiO2 surface is crucial for understanding its fundamental reactivity, and the direct observation of atomic step edges is still a challenge. AFM is a powerful tool for investigating surface structures with true atomic resolution, and it provides the opportunity to resolve the real structure of step edges with improved techniques. In this work, we successfully imaged the atomic configuration of 001 and 1-11 step edges on the surface of rutile TiO2(110)-(1 × 1), and we present the direct observation of oxygen vacancies along the 1-11 step edges, indicating that one 1-11 step edge site corresponds to one oxygen vacancy using AFM. We also made use of the simultaneous AFM/STM measurements to explore the electronic structure of step edges, which enhanced the evidence of oxygen vacancies existing along the 1-11 step edges and further demonstrated that the 001 step edge was terminated by an O row. The effect of the reduced 1-11 step edges was explored by probing the O2 adsorption and the nucleation behavior of gold clusters. It was found that oxygen vacancies along the 1-11 step edges could contribute to O2 dissociative adsorption and there was no obvious difference compared with the oxygen vacancies on the flat terrace. The reduced step edge and terrace likewise acted as nucleation and growth sites for gold atoms/nanoparticles, in line with previous reports. The present study provides a complete characterization of the atomic configuration of the step edges on the TiO2(110) surface and plays an important role in investigating the surface chemistry of metal oxides.
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Affiliation(s)
- Huan Fei Wen
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
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29
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Maddox W, Acharya DP, Leong GJ, Sutter P, Ciobanu CV. Bias-Dependent Scanning Tunneling Microscopy Signature of Bridging-Oxygen Vacancies on Rutile TiO 2(110). ACS OMEGA 2018; 3:6540-6545. [PMID: 31458830 PMCID: PMC6644455 DOI: 10.1021/acsomega.8b01056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 06/07/2018] [Indexed: 06/10/2023]
Abstract
The rutile TiO2(110) surface has long-served as a well-characterized, prototypical transition-metal oxide surface used in heterogeneous catalysis and photocatalytic water splitting. Naturally occurring defects on this surface, called bridging-oxygen (BO) vacancies, are important as they determine the overall reactivity of the surface. Herein, we report a bias-dependent, scanning tunneling microscopy (STM) signature of the BO vacancies on TiO2(110): for sample bias voltages past a threshold of +3 V, the bright vacancies are flanked on either side (along the oxygen row) by two dark spots approximately shaped like half-moons. The BO vacancies have a bright aspect below the threshold bias also but are not surrounded by half-moon dark depressions. Using generalized gradient approximation calculations with Hubbard correction (GGA + U) for projected density of states (DOS) and simulated STM images, we find that the bias-dependent STM signature originates from (i) local DOS maxima of all BOs (lighter background that occurs above the threshold bias) and (ii) the increased separation between the first and second BO atoms neighboring the vacancy which leads to an apparent dip between these neighboring oxygens. These results offer a new striking example of the STM signature that appears without switching the polarity of the bias. Similar approaches can be employed for seeking distinguishing features on the surfaces of other large band gap semiconductors and insulators.
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Affiliation(s)
- Willie
B. Maddox
- Department
of Mechanical Engineering, Colorado School
of Mines, 1500 Illinois
Street, Golden, Colorado 80401, United States
| | - Danda P. Acharya
- Global
Foundries, 400 Stone
Break Extension, Malta, New
York 12020, United
States
| | - G. Jeremy Leong
- Department
of Mechanical Engineering, Colorado School
of Mines, 1500 Illinois
Street, Golden, Colorado 80401, United States
| | - Peter Sutter
- Department
of Electrical and Computer Engineering, University of Nebraska-Lincoln, P.O.
Box 880511, Lincoln, Nebraska 68588, United States
| | - Cristian V. Ciobanu
- Department
of Mechanical Engineering, Colorado School
of Mines, 1500 Illinois
Street, Golden, Colorado 80401, United States
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30
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Stable contrast mode on TiO 2(110) surface with metal-coated tips using AFM. Ultramicroscopy 2018; 191:51-55. [PMID: 29803917 DOI: 10.1016/j.ultramic.2018.04.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Revised: 03/19/2018] [Accepted: 04/04/2018] [Indexed: 11/20/2022]
Abstract
We investigated a method to obtain a stable contrast mode on the TiO2(110) surface. The stable contrast rate is approximately 95% with a W-coated Si cantilever, which demonstrates that a stable tip apex plays an important role to obtain the real geometry of the surface during atomic force microscopy measurement. Information related to surface structure and tunnelling current on the TiO2(110) surface can be obtained by the W-coated Si cantilever. It is possible to investigate the electronic structure and surface potential on the TiO2(110) surface with atomic resolution. In particular, the proposed method could be widely applied to investigate the catalytic activity and the mechanism of a catalytic reaction by a metal-coated tip in the future.
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31
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Feng H, Xu Z, Ren L, Liu C, Zhuang J, Hu Z, Xu X, Chen J, Wang J, Hao W, Du Y, Dou SX. Activating Titania for Efficient Electrocatalysis by Vacancy Engineering. ACS Catal 2018. [DOI: 10.1021/acscatal.8b00719] [Citation(s) in RCA: 109] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Haifeng Feng
- Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, Wollongong, New South Wales 2500, Australia
- Beihang-UOW Joint Research Centre, Beihang University, Beijing 100191, People’s Republic of China
| | - Zhongfei Xu
- Beihang-UOW Joint Research Centre, Beihang University, Beijing 100191, People’s Republic of China
- Department of Physics and Key Laboratory of Micro-Nano Measurement, Manipulation and Physics, Ministry of Education, Beihang University, Beijing 100191, People’s Republic of China
| | - Long Ren
- Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, Wollongong, New South Wales 2500, Australia
| | - Chen Liu
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Jincheng Zhuang
- Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, Wollongong, New South Wales 2500, Australia
| | - Zhenpeng Hu
- School of Physics, Nankai University, Tianjin 300071, People’s Republic of China
| | - Xun Xu
- Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, Wollongong, New South Wales 2500, Australia
- Beihang-UOW Joint Research Centre, Beihang University, Beijing 100191, People’s Republic of China
| | - Jun Chen
- Intelligent Polymer Research Institute and ARC Centre of Excellence for Electromaterials Science, University of Wollongong, Wollongong, New South Wales 2500, Australia
| | - Jiaou Wang
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Weichang Hao
- Beihang-UOW Joint Research Centre, Beihang University, Beijing 100191, People’s Republic of China
- Department of Physics and Key Laboratory of Micro-Nano Measurement, Manipulation and Physics, Ministry of Education, Beihang University, Beijing 100191, People’s Republic of China
| | - Yi Du
- Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, Wollongong, New South Wales 2500, Australia
- Beihang-UOW Joint Research Centre, Beihang University, Beijing 100191, People’s Republic of China
| | - Shi Xue Dou
- Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, Wollongong, New South Wales 2500, Australia
- Beihang-UOW Joint Research Centre, Beihang University, Beijing 100191, People’s Republic of China
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32
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Arima E, Wen HF, Naitoh Y, Li YJ, Sugawara Y. KPFM/AFM imaging on TiO 2(110) surface in O 2 gas. NANOTECHNOLOGY 2018; 29:105504. [PMID: 29313525 DOI: 10.1088/1361-6528/aaa62c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We have carried out high-speed imaging of the topography and local contact potential difference (LCPD) on rutile TiO2(110) in O2 gas by atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM). We succeeded in KPFM/AFM imaging with atomic resolution at 1 frame min-1 and observed the adsorbate on a hydroxylated TiO2(110) surface. The observed adsorbate is considered to be oxygen adatoms (Oa), hydroperoxyls (HO2), or terminal hydroxyls (OHt). After adsorption, changes in the topography and the LCPD of the adsorbate were observed. This phenomenon is thought to be caused by the charge transfer of the adsorbate. This technique has the potential to observe catalytic behavior with atomic resolution.
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Affiliation(s)
- Eiji Arima
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita 565-0871, Japan
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33
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Mu R, Dahal A, Wang ZT, Dohnálek Z, Kimmel GA, Petrik NG, Lyubinetsky I. Adsorption and Photodesorption of CO from Charged Point Defects on TiO 2(110). J Phys Chem Lett 2017; 8:4565-4572. [PMID: 28880086 DOI: 10.1021/acs.jpclett.7b02052] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The adsorption and photochemistry of CO on rutile TiO2(110) are studied with scanning tunneling microscopy (STM), temperature-programmed desorption, and angle-resolved photon-stimulated desorption (PSD) at low temperatures. Site occupancies, when weighted by the concentration of each kind of adsorption site on the reduced surface, show that the adsorption probability is the highest for the bridging oxygen vacancies (VO). The probability distribution for the different adsorption sites corresponds to very small differences in CO adsorption energies (<0.02 eV). UV irradiation stimulates diffusion and desorption of CO at low temperature. CO photodesorbs primarily from the vacancies with a bimodal angular distribution, indicating some scattering from the surface, which also leads to photostimulated diffusion. Hydroxylation of VO's does not significantly change the CO PSD yield or the angular distribution, which suggests that photodesorption can be initiated by recombination of photogenerated holes with excess electrons localized near the charged point defect (either VO or bridging hydroxyl).
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Affiliation(s)
- Rentao Mu
- Physical and Computational Sciences Directorate and Institute for Integrated Catalysis, Pacific Northwest National Laboratory , Richland, Washington 99352, United States
- Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University; Collaborative Innovation Center of Chemical Science and Engineering , Tianjin 300072, China
| | - Arjun Dahal
- Environmental Molecular Sciences Laboratory and Institute for Integrated Catalysis, Pacific Northwest National Laboratory , Richland, Washington 99352, United States
| | - Zhi-Tao Wang
- Environmental Molecular Sciences Laboratory and Institute for Integrated Catalysis, Pacific Northwest National Laboratory , Richland, Washington 99352, United States
| | - Zdenek Dohnálek
- Physical and Computational Sciences Directorate and Institute for Integrated Catalysis, Pacific Northwest National Laboratory , Richland, Washington 99352, United States
- Voiland School of Chemical Engineering and Bioengineering, Washington State University , Pullman, Washington 99163, United States
| | - Greg A Kimmel
- Physical and Computational Sciences Directorate and Institute for Integrated Catalysis, Pacific Northwest National Laboratory , Richland, Washington 99352, United States
| | - Nikolay G Petrik
- Physical and Computational Sciences Directorate and Institute for Integrated Catalysis, Pacific Northwest National Laboratory , Richland, Washington 99352, United States
| | - Igor Lyubinetsky
- Physical and Computational Sciences Directorate and Institute for Integrated Catalysis, Pacific Northwest National Laboratory , Richland, Washington 99352, United States
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34
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Wang R, Fan H. The location of excess electrons on H2O/TiO2(110) surface and its role in the surface reactions. Mol Phys 2017. [DOI: 10.1080/00268976.2017.1371801] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Ruimin Wang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian, P. R. China
- University of Chinese Academy of Sciences, 19 A Yuquan Road, Beijing, P. R. China
| | - Hongjun Fan
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian, P. R. China
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35
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Shi Y, Sun H, Nguyen MC, Wang C, Ho K, Saidi WA, Zhao J. Structures of defects on anatase TiO 2(001) surfaces. NANOSCALE 2017; 9:11553-11565. [PMID: 28770922 DOI: 10.1039/c7nr02458d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Defects on oxide surfaces play a crucial role in surface reactivity and thus it is crucial to understand their atomic and electronic structures. The defects on anatase TiO2(001)-(1 × 4) surfaces are found to be highly reactive; however, due to the surface reconstruction, the defects exhibit a complicated character in different experiments that make it very challenging to determine their atomic structures. Here we present a systematic first-principles investigation of the defects on anatase TiO2(001)-(1 × 4) surfaces based on a global-search adaptive genetic algorithm (AGA) and density functional theory (DFT). For different Ti-O ratios, we identify the low energy defect structures, investigate their electronic structure using a hybrid functional, and map their regions of stability under realistic conditions. We successfully find novel oxygen vacancy (OV) and Ti interstitial (Tiini) structures that are different from the conventional ones in terms of their charge localization, magnetic state, and their scanning-tunneling-microscopy bright-dark image signature. This provides an insight into the complex geometric and electronic structure of the surface defects, and resolves several experimental discrepancies.
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Affiliation(s)
- Yongliang Shi
- ICQD/Hefei National Laboratory for Physical Sciences at Microscale, and Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences, and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
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36
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Tada K, Koga H, Hayashi A, Kondo Y, Kawakami T, Yamanaka S, Okumura M. Theoretical Clarification of the Coexistence of Cl Effects on Au/TiO2: The Interaction between Au Clusters and the TiO2 Surface, and the Aggregation of Au Clusters on the TiO2 Surface. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2017. [DOI: 10.1246/bcsj.20160359] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Kohei Tada
- Department of Energy and Environment, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043
| | - Hiroaki Koga
- Element Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto University, Katsura, Kyoto 615-8520
| | - Akihide Hayashi
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043
| | - Yudai Kondo
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043
| | - Takashi Kawakami
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043
| | - Shusuke Yamanaka
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043
| | - Mitsutaka Okumura
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043
- Element Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto University, Katsura, Kyoto 615-8520
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37
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Wen HF, Li YJ, Arima E, Naitoh Y, Sugawara Y, Xu R, Cheng ZH. Investigation of tunneling current and local contact potential difference on the TiO 2(110) surface by AFM/KPFM at 78 K. NANOTECHNOLOGY 2017; 28:105704. [PMID: 28164861 DOI: 10.1088/1361-6528/aa5aef] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We propose a new multi-image method for obtaining the frequency shift, tunneling current and local contact potential difference (LCPD) on a TiO2(110) surface with atomic resolution. The tunneling current image reveals rarely observed surface oxygen atoms contrary to the conventional results. We analyze how the surface and subsurface defects affect the distribution of the LCPD. In addition, the subsurface defects are observed clearly in the tunneling current image, in contrast to a topographic image. To clarify the origin of the atomic contrast, we perform site-dependent spectroscopy as a function of the tip-sample distance. The multi-image method is expected to be widely used to investigate the charge transfer phenomena between the nanoparticles and surface sites, and it is useful for elucidating the mechanisms of catalytic reactions.
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Affiliation(s)
- Huan Fei Wen
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
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38
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Wang Y, Wöll C. IR spectroscopic investigations of chemical and photochemical reactions on metal oxides: bridging the materials gap. Chem Soc Rev 2017; 46:1875-1932. [DOI: 10.1039/c6cs00914j] [Citation(s) in RCA: 130] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
In this review, we highlight recent progress (2008–2016) in infrared reflection absorption spectroscopy (IRRAS) studies on oxide powders achieved by using different types of metal oxide single crystals as reference systems.
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Affiliation(s)
- Yuemin Wang
- Institute of Functional Interfaces
- Karlsruhe Institute of Technology
- Eggenstein-Leopoldshafen
- Germany
| | - Christof Wöll
- Institute of Functional Interfaces
- Karlsruhe Institute of Technology
- Eggenstein-Leopoldshafen
- Germany
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39
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Setvín M, Wagner M, Schmid M, Parkinson GS, Diebold U. Surface point defects on bulk oxides: atomically-resolved scanning probe microscopy. Chem Soc Rev 2017; 46:1772-1784. [DOI: 10.1039/c7cs00076f] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Metal oxides are abundant in nature and they are some of the most versatile materials for applications ranging from catalysis to novel electronics.
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Affiliation(s)
- Martin Setvín
- Institute of Applied Physics
- TU Wien
- A-1040 Vienna
- Austria
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40
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Kou L, Li YJ, Kamijyo T, Naitoh Y, Sugawara Y. Investigation of the surface potential of TiO 2 (110) by frequency-modulation Kelvin probe force microscopy. NANOTECHNOLOGY 2016; 27:505704. [PMID: 27861162 DOI: 10.1088/0957-4484/27/50/505704] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
We investigate the surface potential distribution on a TiO2 (110)-1 × 1 surface by Kelvin probe force microscopy (KPFM) and atom-dependent bias-distance spectroscopic mapping. The experimental results demonstrate that the local contact potential difference increases on twofold-coordinated oxygen sites, and decreases on OH defects and fivefold-coordinated Ti sites. We propose a qualitative model to explain the origin of the surface potential of TiO2 (110). We qualitatively calculate the surface potential induced by chemical potential and permanent surface dipole. The calculated results agree with our experimental ones. Therefore, we suggest that the surface potential of TiO2 (110) is dominated not only by the permanent surface dipole between the tip apex atom and surface, but also by the dipoles induced by the chemical interaction between the tip and sample. The KPFM technique demonstrate the possibility of investigation of the charge transfer phenomenon on TiO2 surface under gas conditions. It is useful for the elucidation of the mechanism of the catalytic reactions.
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Affiliation(s)
- Lili Kou
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
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41
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Prauzner-Bechcicki JS, Zajac L, Olszowski P, Jöhr R, Hinaut A, Glatzel T, Such B, Meyer E, Szymonski M. Scanning probe microscopy studies on the adsorption of selected molecular dyes on titania. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2016; 7:1642-1653. [PMID: 28144513 PMCID: PMC5238678 DOI: 10.3762/bjnano.7.156] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 10/20/2016] [Indexed: 06/06/2023]
Abstract
Titanium dioxide, or titania, sensitized with organic dyes is a very attractive platform for photovoltaic applications. In this context, the knowledge of properties of the titania-sensitizer junction is essential for designing efficient devices. Consequently, studies on the adsorption of organic dyes on titania surfaces and on the influence of the adsorption geometry on the energy level alignment between the substrate and an organic adsorbate are necessary. The method of choice for investigating the local environment of a single dye molecule is high-resolution scanning probe microscopy. Microscopic results combined with the outcome of common spectroscopic methods provide a better understanding of the mechanism taking place at the titania-sensitizer interface. In the following paper, we review the recent scanning probe microscopic research of a certain group of molecular assemblies on rutile titania surfaces as it pertains to dye-sensitized solar cell applications. We focus on experiments on adsorption of three types of prototypical dye molecules, i.e., perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA), phtalocyanines and porphyrins. Two interesting heteromolecular systems comprising molecules that are aligned with the given review are discussed as well.
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Affiliation(s)
- Jakub S Prauzner-Bechcicki
- Research Centre for Nanometer-scale Science and Advanced Materials (NANOSAM), Institute of Physics, Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, Łojasiewicza 11, 30-348 Krakow, Poland
| | - Lukasz Zajac
- Research Centre for Nanometer-scale Science and Advanced Materials (NANOSAM), Institute of Physics, Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, Łojasiewicza 11, 30-348 Krakow, Poland
| | - Piotr Olszowski
- Research Centre for Nanometer-scale Science and Advanced Materials (NANOSAM), Institute of Physics, Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, Łojasiewicza 11, 30-348 Krakow, Poland
| | - Res Jöhr
- Department of Physics, University of Basel, Klingelbergstr. 82, 4056 Basel, Switzerland
| | - Antoine Hinaut
- Department of Physics, University of Basel, Klingelbergstr. 82, 4056 Basel, Switzerland
| | - Thilo Glatzel
- Department of Physics, University of Basel, Klingelbergstr. 82, 4056 Basel, Switzerland
| | - Bartosz Such
- Research Centre for Nanometer-scale Science and Advanced Materials (NANOSAM), Institute of Physics, Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, Łojasiewicza 11, 30-348 Krakow, Poland
| | - Ernst Meyer
- Department of Physics, University of Basel, Klingelbergstr. 82, 4056 Basel, Switzerland
| | - Marek Szymonski
- Research Centre for Nanometer-scale Science and Advanced Materials (NANOSAM), Institute of Physics, Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, Łojasiewicza 11, 30-348 Krakow, Poland
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42
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Yim CM, Watkins MB, Wolf MJ, Pang CL, Hermansson K, Thornton G. Engineering Polarons at a Metal Oxide Surface. PHYSICAL REVIEW LETTERS 2016; 117:116402. [PMID: 27661706 DOI: 10.1103/physrevlett.117.116402] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Indexed: 06/06/2023]
Abstract
Polarons in metal oxides are important in processes such as catalysis, high temperature superconductivity, and dielectric breakdown in nanoscale electronics. Here, we study the behavior of electron small polarons associated with oxygen vacancies at rutile TiO_{2}(110), using a combination of low temperature scanning tunneling microscopy (STM), density functional theory, and classical molecular dynamics calculations. We find that the electrons are symmetrically distributed around isolated vacancies at 78 K, but as the temperature is reduced, their distributions become increasingly asymmetric, confirming their polaronic nature. By manipulating isolated vacancies with the STM tip, we show that particular configurations of polarons are preferred for given locations of the vacancies, which we ascribe to small residual electric fields in the surface. We also form a series of vacancy complexes and manipulate the Ti ions surrounding them, both of which change the associated electronic distributions. Thus, we demonstrate that the configurations of polarons can be engineered, paving the way for the construction of conductive pathways relevant to resistive switching devices.
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Affiliation(s)
- C M Yim
- Department of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - M B Watkins
- School of Mathematics and Physics, University of Lincoln, Brayford Pool, Lincoln LN6 7TS, United Kingdom
| | - M J Wolf
- Department of Physics & Astronomy and London Centre for Nanotechnology, University College London, Gower Street, London WC1E 6BT, United Kingdom
- Department of Chemistry, Ångström Laboratory, Uppsala University, Box 538, S-751 21 Uppsala, Sweden
| | - C L Pang
- Department of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - K Hermansson
- Department of Chemistry, Ångström Laboratory, Uppsala University, Box 538, S-751 21 Uppsala, Sweden
| | - G Thornton
- Department of Chemistry and London Centre for Nanotechnology, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
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43
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Yamakawa K, Sato Y, Fukutani K. Asymmetric and symmetric absorption peaks observed in infrared spectra of CO2 adsorbed on TiO2 nanotubes. J Chem Phys 2016; 144:154703. [DOI: 10.1063/1.4946790] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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44
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Guo Q, Zhou C, Ma Z, Ren Z, Fan H, Yang X. Elementary photocatalytic chemistry on TiO2surfaces. Chem Soc Rev 2016; 45:3701-30. [DOI: 10.1039/c5cs00448a] [Citation(s) in RCA: 250] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
In this article, we review the recent advances in the photoreactions of small molecules with model TiO2surfaces, and propose a photocatalytical model based on nonadiabatic dynamics and ground state surface reactions.
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Affiliation(s)
- Qing Guo
- State Key Laboratory of Molecular Reaction Dynamics
- Dalian Institute of Chemical Physics
- Dalian 116023
- P. R. China
| | - Chuanyao Zhou
- State Key Laboratory of Molecular Reaction Dynamics
- Dalian Institute of Chemical Physics
- Dalian 116023
- P. R. China
| | - Zhibo Ma
- State Key Laboratory of Molecular Reaction Dynamics
- Dalian Institute of Chemical Physics
- Dalian 116023
- P. R. China
| | - Zefeng Ren
- International Center for Quantum Materials and School of Physics
- Peking University
- Beijing
- P. R. China
- Collaborative Innovation Center of Quantum Matter
| | - Hongjun Fan
- State Key Laboratory of Molecular Reaction Dynamics
- Dalian Institute of Chemical Physics
- Dalian 116023
- P. R. China
| | - Xueming Yang
- State Key Laboratory of Molecular Reaction Dynamics
- Dalian Institute of Chemical Physics
- Dalian 116023
- P. R. China
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45
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Wang ZT, Henderson MA, Lyubinetsky I. Origin of Coverage Dependence in Photoreactivity of Carboxylate on TiO2(110): Hindering by Charged Coadsorbed Hydroxyls. ACS Catal 2015. [DOI: 10.1021/acscatal.5b01819] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Zhi-Tao Wang
- EMSL, Institute
for Integrated Catalysis, and Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Michael A. Henderson
- Fundamental and
Computational Sciences Directorate, Institute for Integrated Catalysis,
and Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Igor Lyubinetsky
- EMSL, Institute
for Integrated Catalysis, and Pacific Northwest National Laboratory, Richland, Washington 99352, United States
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46
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Zhang Y, Payne DT, Pang CL, Fielding H, Thornton G. Non-Band-Gap Photoexcitation of Hydroxylated TiO2. J Phys Chem Lett 2015; 6:3391-5. [PMID: 26267712 PMCID: PMC4603613 DOI: 10.1021/acs.jpclett.5b01508] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 08/12/2015] [Indexed: 06/04/2023]
Abstract
The photochemistry of TiO2 has been studied intensively since it was discovered that TiO2 can act as a photocatalyst. Nevertheless, it has proven difficult to establish the detailed charge-transfer processes involved, partly because the excited states involved are difficult to study. Here we present evidence of the existence of hydroxyl-induced excited states in the conduction band region. Using two-photon photoemission, we show that stepwise photoexcitation from filled band gap states lying 0.8 eV below the Fermi level of rutile TiO2(110) excites hydroxyl-induced states 2.73 eV above the Fermi level that has an onset energy of ∼3.1 eV. The onset is shifted to lower energy by the coadsorption of molecular water, which suggests a means of tuning the energy of the excited state.
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Affiliation(s)
- Yu Zhang
- Department
of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
- London
Centre for Nanotechnology, University College
London, 17-19 Gordon
Street, London WC1H 0AH, United Kingdom
| | - Daniel T. Payne
- Department
of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
- London
Centre for Nanotechnology, University College
London, 17-19 Gordon
Street, London WC1H 0AH, United Kingdom
| | - Chi L. Pang
- Department
of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
- London
Centre for Nanotechnology, University College
London, 17-19 Gordon
Street, London WC1H 0AH, United Kingdom
| | - Helen
H. Fielding
- Department
of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Geoff Thornton
- Department
of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
- London
Centre for Nanotechnology, University College
London, 17-19 Gordon
Street, London WC1H 0AH, United Kingdom
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47
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Tan SJ, Wang B. Active Sites for Adsorption and Reaction of Molecules on Rutile TiO2(110) and Anatase TiO2(001) Surfaces. CHINESE J CHEM PHYS 2015. [DOI: 10.1063/1674-0068/28/cjcp1506129] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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48
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Minato T, Kajita S, Pang CL, Asao N, Yamamoto Y, Nakayama T, Kawai M, Kim Y. Tunneling Desorption of Single Hydrogen on the Surface of Titanium Dioxide. ACS NANO 2015; 9:6837-6842. [PMID: 26158720 DOI: 10.1021/acsnano.5b01607] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We investigated the reaction mechanism of the desorption of single hydrogen from a titanium dioxide surface excited by the tip of a scanning tunneling microscope (STM). Analysis of the desorption yield, in combination with theoretical calculations, indicates the crucial role played by the applied electric field. Instead of facilitating desorption by reducing the barrier height, the applied electric field causes a reduction in the barrier width, which, when coupled with the electron excitation induced by the STM tip, leads to the tunneling desorption of the hydrogen. A significant reduction in the desorption yield was observed when deuterium was used instead of hydrogen, providing further support for the tunneling-desorption mechanism.
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Affiliation(s)
- Taketoshi Minato
- †International Advanced Research and Education Organization, Tohoku University, Sendai 980-8578, Japan
- ‡Surface and Interface Science Laboratory, RIKEN, 2-1 Hirosawa, Saitama 351-0198, Japan
| | - Seiji Kajita
- §Department of Physics, Chiba University, 1-33 Yayoi, Inage, Chiba 263-0022, Japan
| | - Chi-Lun Pang
- ∥Department of Chemistry, University College London, London WC1H 0AJ, United Kingdom
| | - Naoki Asao
- ⊥WPI Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan
| | - Yoshinori Yamamoto
- ⊥WPI Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Sendai 980-8577, Japan
| | - Takashi Nakayama
- §Department of Physics, Chiba University, 1-33 Yayoi, Inage, Chiba 263-0022, Japan
| | - Maki Kawai
- #Department of Advanced Materials Science, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan
| | - Yousoo Kim
- ‡Surface and Interface Science Laboratory, RIKEN, 2-1 Hirosawa, Saitama 351-0198, Japan
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49
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Sun H, Mowbray DJ, Migani A, Zhao J, Petek H, Rubio A. Comparing Quasiparticle H2O Level Alignment on Anatase and Rutile TiO2. ACS Catal 2015. [DOI: 10.1021/acscatal.5b00529] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Huijuan Sun
- Nano-Bio
Spectroscopy Group and ETSF Scientific Development Center, Departamento
de Física de Materiales, Centro de Física de Materiales
CSIC-UPV/EHU-MPC and DIPC, Universidad del País Vasco UPV/EHU, E-20018 San Sebastián, Spain
| | - Duncan J. Mowbray
- Nano-Bio
Spectroscopy Group and ETSF Scientific Development Center, Departamento
de Física de Materiales, Centro de Física de Materiales
CSIC-UPV/EHU-MPC and DIPC, Universidad del País Vasco UPV/EHU, E-20018 San Sebastián, Spain
| | - Annapaola Migani
- ICN2−Institut Català de Nanociència i Nanotecnologia, ICN2 Building, Campus UAB, E-08193 Bellaterra (Barcelona), Spain
- CSIC−Consejo Superior de Investigaciones Científicas, ICN2 Building, Campus UAB, E-08193 Bellaterra (Barcelona), Spain
| | | | - Hrvoje Petek
- Department
of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Angel Rubio
- Nano-Bio
Spectroscopy Group and ETSF Scientific Development Center, Departamento
de Física de Materiales, Centro de Física de Materiales
CSIC-UPV/EHU-MPC and DIPC, Universidad del País Vasco UPV/EHU, E-20018 San Sebastián, Spain
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, D-22761 Hamburg, Germany
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50
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Shindo M, Manaka T, Shudo KI. Clusterization modes of Ti on TiO2(1 1 0)-1 × 1 due to stablization by catalytic suboxide formation. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:122001. [PMID: 25756901 DOI: 10.1088/0953-8984/27/12/122001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The electronic states of individual clusters formed from Ti deposition on a TiO(2)(1 1 0)-1 × 1 surface were measured using scanning tunneling spectroscopy (STS). The results of scanning tunneling microscopy (STM) suggests that as the amount of deposited Ti increased, at a critical height of 1.4 nm, the cluster growth changes from vertical oxide formation to lateral growth. Based on the STS spectra, the relation between the band-gap and cluster size was revealed. In the first oxide-formation mode, the band gaps decreased smoothly in response to the increase of the cluster size, while a band-gap-free (metallic) phase appears when the clusters are thicker than ∼1.4 nm. This result indicates that Ti adatoms initially diffuse on the oxide surface and are stabilized by oxygen atoms from the substrate to form a suboxide interfacial layer. This catalytic suboxide formation promotes the vertical granular growth of the deposited Ti atoms.
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Affiliation(s)
- Masako Shindo
- Faculty of Engineering Science, Yokohama National University, Tokiwadai 79-5, Hodogaya-ku, Yokohama 240-8501, Japan
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