1
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Dalecky L, Sottile F, Hung L, Cazals L, Desolneux A, Chevalier A, Rueff JP, Bertrand L. Non-resonant inelastic X-ray scattering for discrimination of pigments. Phys Chem Chem Phys 2024; 26:4363-4371. [PMID: 38235804 DOI: 10.1039/d3cp04753a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2024]
Abstract
Inelastic X-ray scattering (IXS) spectroscopy has been used in many fields of solid-state physics and theoretical chemistry as an accurate and quantitative probe of elementary excitations. We show that non-resonant IXS spectra in the energy loss range below 100 eV exhibit a strong contrast across a wide range of commercially available pigments, opening new routes for their discrimination. These signatures combine plasmonic transitions, collective excitations and low energy absorption edges. We have performed IXS to discriminate different artists' pigments within complex mixtures and to quantitatively determine rutile and anatase polymorphs of TiO2. The integration of experimental data on pigment powders with suitable ab initio simulations shows a precise fit of the spectroscopic data both in the position of the resonances and in their relative intensity.
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Affiliation(s)
- Lauren Dalecky
- Université Paris-Saclay, ENS Paris-Saclay, CNRS, Photophysique et Photochimie Supramoléculaires et Macromoléculaires, 91190 Gif-sur-Yvette, France.
| | - Francesco Sottile
- ETSF and LSI, CNRS, CEA/DRF/IRAMIS, École Polytechnique, Institut Polytechnique de Paris, F-91120 Palaiseau, France
| | - Linda Hung
- Energy and Materials Division, Toyota Research Institute, Los Altos, CA 94022, USA
| | - Laure Cazals
- Université Paris-Saclay, ENS Paris-Saclay, CNRS, Photophysique et Photochimie Supramoléculaires et Macromoléculaires, 91190 Gif-sur-Yvette, France.
| | - Agnès Desolneux
- Université Paris-Saclay, ENS Paris-Saclay, CNRS, Centre Borelli, 91190 Gif-sur-Yvette, France
| | - Aurélia Chevalier
- Conservation of Cultural Heritage - Aurélia Chevalier Sàrl, Route des Jeunes 4bis, 1227 Les Acacias, Genève, Switzerland
| | - Jean-Pascal Rueff
- Synchrotron SOLEIL, L'Orme des Merisiers, BP 48 Saint-Aubin, 91192 Gif-sur-Yvette, France
- Laboratoire de Chimie Physique - Matière et Rayonnement (LCPMR), Sorbonne Université, CNRS, 75005 Paris, France
| | - Loïc Bertrand
- Université Paris-Saclay, ENS Paris-Saclay, CNRS, Photophysique et Photochimie Supramoléculaires et Macromoléculaires, 91190 Gif-sur-Yvette, France.
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2
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Guo S, Yun H, Nair S, Jalan B, Mkhoyan KA. Mending cracks atom-by-atom in rutile TiO 2 with electron beam radiolysis. Nat Commun 2023; 14:6005. [PMID: 37752136 PMCID: PMC10522652 DOI: 10.1038/s41467-023-41781-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2023] [Accepted: 09/13/2023] [Indexed: 09/28/2023] Open
Abstract
Rich electron-matter interactions fundamentally enable electron probe studies of materials such as scanning transmission electron microscopy (STEM). Inelastic interactions often result in structural modifications of the material, ultimately limiting the quality of electron probe measurements. However, atomistic mechanisms of inelastic-scattering-driven transformations are difficult to characterize. Here, we report direct visualization of radiolysis-driven restructuring of rutile TiO2 under electron beam irradiation. Using annular dark field imaging and electron energy-loss spectroscopy signals, STEM probes revealed the progressive filling of atomically sharp nanometer-wide cracks with striking atomic resolution detail. STEM probes of varying beam energy and precisely controlled electron dose were found to constructively restructure rutile TiO2 according to a quantified radiolytic mechanism. Based on direct experimental observation, a "two-step rolling" model of mobile octahedral building blocks enabling radiolysis-driven atomic migration is introduced. Such controlled electron beam-induced radiolytic restructuring can be used to engineer novel nanostructures atom-by-atom.
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Affiliation(s)
- Silu Guo
- Chemical Engineering and Materials Science, University of Minnesota, Twin Cities, Minneapolis, MN, 55455, USA
| | - Hwanhui Yun
- Chemical Engineering and Materials Science, University of Minnesota, Twin Cities, Minneapolis, MN, 55455, USA
- Korea Research Institute of Chemical Technology, Daejeon, 34114, Korea
| | - Sreejith Nair
- Chemical Engineering and Materials Science, University of Minnesota, Twin Cities, Minneapolis, MN, 55455, USA
| | - Bharat Jalan
- Chemical Engineering and Materials Science, University of Minnesota, Twin Cities, Minneapolis, MN, 55455, USA
| | - K Andre Mkhoyan
- Chemical Engineering and Materials Science, University of Minnesota, Twin Cities, Minneapolis, MN, 55455, USA.
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3
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Wei Z, Zhou Z, Liu Y, Chen S, Wu Y, Jian H, Pan Z, Hu G. Self-Competitive Adsorption Behavior of Arsenic on the TiO 2 Surface. ACS OMEGA 2023; 8:31201-31214. [PMID: 37663490 PMCID: PMC10468773 DOI: 10.1021/acsomega.3c03214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Accepted: 08/01/2023] [Indexed: 09/05/2023]
Abstract
TiO2 is a commonly used material to remove arsenic from drinking water by adsorption as well as photocatalytic oxidation (PCO). In the present paper, arsenic adsorption and PCO at different pH environments are studied on the (1 1 0) facet of rutile TiO2 (r-TiO2). A self-competitive adsorption (SCA) behavior of arsenic is observed; i.e., arsenic species compete to adsorb on the surface. Related DFT calculations are carried out to simulate adsorption. SCA behavior is the key to connecting calculation results with experimental results. Furthermore, PCO of arsenite is performed at different pH values. Of note, PCO is related to adsorption; namely, the adsorption process determines the whole PCO reaction speed. Therefore, SCA is also helpful for the PCO reaction. The SCA behavior is useful not only for arsenic on r-TiO2 but also for arsenic on anatase TiO2 (a-TiO2). It may be helpful to further study arsenic adsorption and PCO on other materials such as Fe2O3 and MnO2. The SCA behavior extends our understanding of arsenic and provides new insights into arsenic removal and its cycle in nature.
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Affiliation(s)
- Zhigang Wei
- School
of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006, P.R China
| | - Zhixin Zhou
- School
of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006, P.R China
| | - Yue Liu
- School
of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006, P.R China
| | - Shiyun Chen
- School
of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006, P.R China
| | - Yang Wu
- College
of Chemistry, Liaoning University, Shenyang 110036, P. R. China
| | - Huixia Jian
- School
of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006, P.R China
| | - Zhanchang Pan
- School
of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006, P.R China
| | - Guanghui Hu
- School
of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006, P.R China
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4
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Chen D, Wang Y, Dronskowski R. Computational Design and Theoretical Properties of WC 3N 6, an H-Free Melaminate and Potential Multifunctional Material. J Am Chem Soc 2023; 145:6986-6993. [PMID: 36920250 DOI: 10.1021/jacs.3c00631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
Abstract
By means of first-principles theory, existence, synthetic conditions, and structural as well as physicochemical properties have been predicted for the first hydrogen-free melaminate salt of the composition WC3N6. We find at least two energetically favorable polymorphs adopting space groups P1 and P3, both of which are layer-like porous materials. In addition to sizable Madelung fields stabilizing saltlike WC3N6, the complex C3N66- anions are connected via perfectly optimized W-N bonds, forming WN5 in the P1 and WN6 coordination polyhedra in the P3 polymorphs. The band gaps of the P1 and P3 phases are HSE-predicted as 2.25 and 1.21 eV, respectively, significantly smaller than those of g-C3N4 and WO3. Moreover, both phases have suitable band-edge potentials that may provide sufficient driving force for photocatalytic water splitting; at least for the P1 phase, there is also a reasonable chance for reduced electron-hole recombination. In addition, the polymorphs's large optical absorption coefficients should greatly enhance the photocatalytic performance. WC3N6 defines a new class of compounds and has unique structural characteristics, mirrored from its electrical and optical properties, and it should provide another chemical path for preparing efficient photocatalysts and optoelectronic devices.
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Affiliation(s)
- Da Chen
- Hoffmann Institute of Advanced Materials, Shenzhen Polytechnic, 518055 Shenzhen, China.,Chair of Solid-State and Quantum Chemistry, Institute of Inorganic Chemistry, RWTH Aachen University, D-52056 Aachen, Germany
| | - YiXu Wang
- Chair of Solid-State and Quantum Chemistry, Institute of Inorganic Chemistry, RWTH Aachen University, D-52056 Aachen, Germany
| | - Richard Dronskowski
- Hoffmann Institute of Advanced Materials, Shenzhen Polytechnic, 518055 Shenzhen, China.,Chair of Solid-State and Quantum Chemistry, Institute of Inorganic Chemistry, RWTH Aachen University, D-52056 Aachen, Germany
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5
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Eddy DR, Permana MD, Sakti LK, Sheha GAN, Solihudin, Hidayat S, Takei T, Kumada N, Rahayu I. Heterophase Polymorph of TiO 2 (Anatase, Rutile, Brookite, TiO 2 (B)) for Efficient Photocatalyst: Fabrication and Activity. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:704. [PMID: 36839072 PMCID: PMC9965282 DOI: 10.3390/nano13040704] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Revised: 02/07/2023] [Accepted: 02/08/2023] [Indexed: 07/30/2023]
Abstract
TiO2 exists naturally in three crystalline forms: Anatase, rutile, brookite, and TiO2 (B). These polymorphs exhibit different properties and consequently different photocatalytic performances. This paper aims to clarify the differences between titanium dioxide polymorphs, and the differences in homophase, biphase, and triphase properties in various photocatalytic applications. However, homophase TiO2 has various disadvantages such as high recombination rates and low adsorption capacity. Meanwhile, TiO2 heterophase can effectively stimulate electron transfer from one phase to another causing superior photocatalytic performance. Various studies have reported the biphase of polymorph TiO2 such as anatase/rutile, anatase/brookite, rutile/brookite, and anatase/TiO2 (B). In addition, this paper also presents the triphase of the TiO2 polymorph. This review is mainly focused on information regarding the heterophase of the TiO2 polymorph, fabrication of heterophase synthesis, and its application as a photocatalyst.
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Affiliation(s)
- Diana Rakhmawaty Eddy
- Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Padjadjaran, Sumedang 45363, West Java, Indonesia
| | - Muhamad Diki Permana
- Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Padjadjaran, Sumedang 45363, West Java, Indonesia
- Integrated Graduate School of Medicine, Engineering, and Agricultural Sciences, University of Yamanashi, Kofu 400-8511, Japan
- Center for Crystal Science and Technology, University of Yamanashi, Kofu 400-8511, Japan
| | - Lintang Kumoro Sakti
- Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Padjadjaran, Sumedang 45363, West Java, Indonesia
| | - Geometry Amal Nur Sheha
- Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Padjadjaran, Sumedang 45363, West Java, Indonesia
| | - Solihudin
- Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Padjadjaran, Sumedang 45363, West Java, Indonesia
| | - Sahrul Hidayat
- Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Padjadjaran, Sumedang 45363, West Java, Indonesia
| | - Takahiro Takei
- Center for Crystal Science and Technology, University of Yamanashi, Kofu 400-8511, Japan
| | - Nobuhiro Kumada
- Center for Crystal Science and Technology, University of Yamanashi, Kofu 400-8511, Japan
| | - Iman Rahayu
- Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Padjadjaran, Sumedang 45363, West Java, Indonesia
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6
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Zhu Y, Long R. Density Functional Theory Half-Electron Self-Energy Correction for Fast and Accurate Nonadiabatic Molecular Dynamics. J Phys Chem Lett 2021; 12:10886-10892. [PMID: 34730966 DOI: 10.1021/acs.jpclett.1c03077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The nonadiabatic (NA) process is crucial to photochemistry and photophysics and requires an atomistic understanding. However, conventional NA molecular dynamics (MD) for condensed-phase materials on the nanoscale are generally limited to the semilocal exchange-correlation functional, which suffers from the bandgap and thus NA coupling (NAC) problems. We consider TiO2 and a black phosphorus monolayer as two prototypical systems, perform NA-MD simulations of nonradiative electron-hole recombination, and demonstrate for the first time that density functional theory (DFT) half-electron self-energy correction can reproduce the bandgap, effective masses of carriers, luminescence line widths, NAC, and excited-state lifetimes of the two systems at the hybrid functional level while the computational cost remains at that of the Predew-Burke-Ernzerhof functional. Our study indicates that the DFT-1/2 method can greatly accelerate NA-MD simulations while maintaining the accuracy of the hybrid functional, providing an advantage for studying photoexcitation dynamics for large-scale condensed-phase materials.
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Affiliation(s)
- Yonghao Zhu
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Run Long
- College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, Beijing Normal University, Beijing 100875, People's Republic of China
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7
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Miyoshi A, Kuwabara A, Maeda K. Effects of Nitrogen/Fluorine Codoping on Photocatalytic Rutile TiO 2 Crystal Studied by First-Principles Calculations. Inorg Chem 2021; 60:2381-2389. [PMID: 33497215 DOI: 10.1021/acs.inorgchem.0c03262] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nitrogen/fluorine codoping of rutile TiO2 was recently reported to be effective for introducing visible-light absorption, and the resultant TiO2:N,F worked efficiently as an O2 evolution photocatalyst in a Z-scheme water-splitting system. Although an increase in the amount of nitrogen doped into rutile TiO2 lattice in the presence of fluorine was experimentally demonstrated, the role of fluorine in the system remained unclear. Here, we report a computational study on TiO2:N,F through the construction of supercell models with substitutional defects to reveal the atomic arrangement of the material and the electronic band structure. Calculations for all possible structures of nitrogen/fluorine and nitrogen/oxygen-vacancy relative positions revealed that the defect complexes were preferentially located on the (110) plane and that the distance between defects did not have a strong correlation with the formation energy. The present work also showed that although fluorine did not directly contribute to the narrowing of the band gap of TiO2:N,F, the fluorine activity of the synthetic atmosphere promotes the formation of substitutional defect complexes of nitrogen/fluorine for anion sites. This eventually increases the amount of nitrogen incorporated into the rutile TiO2 lattice and also results in reduction of the amount of oxygen vacancy, which is in qualitative agreement with our previous result of transient absorption measurement for rutile TiO2:N,F. The role of fluorine in TiO2:N,F is thus clarified through our systematic first-principles calculations.
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Affiliation(s)
- Akinobu Miyoshi
- Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1-NE-2 Ookayama, Meguro-ku, Tokyo 152-8550, Japan.,Japan Society for the Promotion of Science, Kojimachi Business Center Building, 5-3-1 Kojimachi, Chiyoda-ku, Tokyo 102-0083, Japan
| | - Akihide Kuwabara
- Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya 456-8587, Japan
| | - Kazuhiko Maeda
- Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1-NE-2 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
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8
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Woicik JC, Weiland C, Jaye C, Fischer DA, Rumaiz AK, Shirley EL, Kas JJ, Rehr JJ. Charge-transfer satellites and chemical bonding in photoemission and x-ray absorption of SrTiO 3 and rutile TiO 2: Experiment and first-principles theory with general application to spectroscopic analysis. PHYSICAL REVIEW. B 2020; 101:10.1103/physrevb.101.245119. [PMID: 34409240 PMCID: PMC8370030 DOI: 10.1103/physrevb.101.245119] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
First-principles, real-time-cumulant, and Bethe-Salpeter-equation calculations fully capture the detailed satellite structure that occurs in response to the sudden creation of the core hole in both photoemission and x-ray absorption spectra of the transition-metal compounds SrTiO3 and rutile TiO2. Analysis of the excited-state, real-space charge-density fluctuations betrays the physical nature of these many electron excitations that are shown to reflect the materials' solid-state electronic structure and chemical bonding. This first-principles development of the cumulant-based core hole spectral function is generally applicable to other systems and should become a standard tool for all similar spectroscopic analysis going beyond the quasiparticle physics of the photoelectric effect.
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Affiliation(s)
- J C Woicik
- Materials Measurement Science Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - C Weiland
- Materials Measurement Science Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - C Jaye
- Materials Measurement Science Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - D A Fischer
- Materials Measurement Science Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - A K Rumaiz
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - E L Shirley
- Sensor Science Division, Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - J J Kas
- Department of Physics, University of Washington, Seattle, Washington 98195, USA
| | - J J Rehr
- Department of Physics, University of Washington, Seattle, Washington 98195, USA
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9
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Abd Samad NA, Lai CW, Johan MR. Chemical studies of metal oxide powders. METAL OXIDE POWDER TECHNOLOGIES 2020:17-29. [DOI: 10.1016/b978-0-12-817505-7.00002-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
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10
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Absorption and Remission Characterization of Pure, Dielectric (Nano-)Powders Using Diffuse Reflectance Spectroscopy: An End-To-End Instruction. APPLIED SCIENCES-BASEL 2019. [DOI: 10.3390/app9224933] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
This paper addresses the challenging task of optical characterization of pure, dielectric (nano-)powders with the aim to provide an end-to-end instruction from appropriate sample preparation up to the determination of material remission and absorption spectra. We succeeded in establishing an innovative preparation procedure to reproducibly obtain powder pellet samples with an ideal Lambertian scattering behavior. As a result, a procedure based on diffuse reflectance spectroscopy was developed that allows for (i) performing reproducible and artifact-free, high-quality measurements as well as (ii) a thorough optical analysis using Monte Carlo and Mie scattering simulations yielding the absorption spectrum in the visible spectral range. The procedure is valid for the particular case of powders that can be compressed into thick, non-translucent pellets and neither requires embedding of the dielectric (nano-)powders within an appropriate host matrix for measurements nor the use of integrating spheres. The reduced spectroscopic procedure minimizes the large number of sources for errors, enables an in-depth understanding of non-avoidable artifacts and is of particular advantage in the field of material sciences, i.e., for getting first insights to the optical features of a newly synthesized, pure dielectric powder, but also as an inline inspection tool for massively parallelised material characterization.
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11
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A Mild in-Situ Method to Construct Fe-Doped Cauliflower-Like Rutile TiO2 Photocatalysts for Degradation of Organic Dye in Wastewater. Catalysts 2019. [DOI: 10.3390/catal9050426] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
A mild in situ method was developed to construct an iron doped rutile TiO2 photocatalyst like cauliflower for degradation synthetic textile dye-methyl orange. The synthesized photocatalysts presented distinguished photocatalytic activity. At the optimal Fe concentration (0.5%), the decomposition rate of methyl orange (MO) was about 90% under 40 min of ultraviolet (UV) light irradiation. Whereas, to our knowledge, only 70% of the decomposition rate of MO was achieved by commercial photocatalyst P25 under the similar reaction condition. Additionally, the rutile preparation temperature did not exceed 100 °C, which was much lower than the traditional preparation calcination temperature (e.g., 600 °C). The specific surface area of Fe doped catalysts was bigger than that of the control sample and the catalyst characterization indicated that the doped iron was incorporated into the rutile TiO2 lattice and resulted in the lattice disorder. The lattice disorder would have generated surface defects in the crystal structure, which was in favor of the photocatalytic reaction. The UV-Vis diffuse refection characterization and Density Functional Theory (DFT) calculation suggested that doping a small amount of Fe into the lattice of rutile would lead to a narrower band gap and the formation of a doping energy level between conduction and valence bands of TiO2. This further increased the degradation efficiency of synthetic textile dyes in wastewaters. Our study has provided a relatively easy operation for synthesis Fe doped rutile TiO2, which is a benefit to decrease the cost in wastewater treatment process.
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12
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Wen B, Hao Q, Yin WJ, Zhang L, Wang Z, Wang T, Zhou C, Selloni A, Yang X, Liu LM. Electronic structure and photoabsorption of Ti3+ ions in reduced anatase and rutile TiO2. Phys Chem Chem Phys 2018; 20:17658-17665. [DOI: 10.1039/c8cp02648c] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have used two-photon photoemission (2PPE) spectroscopy and first-principles density functional theory calculations to investigate the electronic structure and photoabsorption of the reduced anatase TiO2(101) and rutile TiO2(110) surfaces.
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Affiliation(s)
- Bo Wen
- Beijing Computational Science Research Center
- Beijing
- P. R. China
| | - Qunqing Hao
- State Key Laboratory of Molecular Reaction Dynamics
- Dalian Institute of Chemical Physics
- Chinese Academy of Science
- Dalian
- P. R. China
| | - Wen-Jin Yin
- Beijing Computational Science Research Center
- Beijing
- P. R. China
| | - Le Zhang
- Beijing Computational Science Research Center
- Beijing
- P. R. China
| | - Zhiqiang Wang
- State Key Laboratory of Molecular Reaction Dynamics
- Dalian Institute of Chemical Physics
- Chinese Academy of Science
- Dalian
- P. R. China
| | - Tianjun Wang
- State Key Laboratory of Molecular Reaction Dynamics
- Dalian Institute of Chemical Physics
- Chinese Academy of Science
- Dalian
- P. R. China
| | - Chuanyao Zhou
- State Key Laboratory of Molecular Reaction Dynamics
- Dalian Institute of Chemical Physics
- Chinese Academy of Science
- Dalian
- P. R. China
| | | | - Xueming Yang
- State Key Laboratory of Molecular Reaction Dynamics
- Dalian Institute of Chemical Physics
- Chinese Academy of Science
- Dalian
- P. R. China
| | - Li-Min Liu
- School of Physics and Nuclear Energy Engineering
- Beihang University
- Beijing 100191
- P. R. China
- Beijing Computational Science Research Center
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13
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Abstract
The oxidation state of titanium in titanium dioxide is commonly assumed to be +4. This assignment is based on the ionic approximation and is used ubiquitously to rationalize phenomena observed with TiO2. It implies a charge state +4 and that no further oxidation of the metal center is possible. We present a comprehensive electronic structure investigation of Ti ions, TiO2 molecules, and TiO2 bulk crystals using different density functional theory and wave function-based approaches, which shows that the charge state of Ti is +3. Specifically, there is evidence of a significant remaining contribution from valence s and d electrons of Ti, including the presence of a nuclear cusp around the Ti core. The charge corresponding to valence s and d states of Ti amounts to 1 e. This suggests the possibility of further oxidation of Ti in TiO2 compounds and challenges the commonly assumed picture of assigning the oxidation state of Ti in titania to +4.
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Affiliation(s)
- Daniel Koch
- Department of Mechanical Engineering, National University of Singapore , 9 Engineering Drive 1, Singapore 117576, Singapore
| | - Sergei Manzhos
- Department of Mechanical Engineering, National University of Singapore , 9 Engineering Drive 1, Singapore 117576, Singapore
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14
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cif2tube – Algorithm for constructing nanotube and nanoscroll models from crystallographic information files. J Taiwan Inst Chem Eng 2016. [DOI: 10.1016/j.jtice.2016.08.030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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15
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Kukovecz Á, Kordás K, Kiss J, Kónya Z. Atomic scale characterization and surface chemistry of metal modified titanate nanotubes and nanowires. SURFACE SCIENCE REPORTS 2016. [DOI: 10.1016/j.surfrep.2016.06.001] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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16
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17
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Mandal BP, Anithakumari P, Nigam S, Majumder C, Mohapatra M, Tyagi AK. Enhancement of dielectric constant in a niobium doped titania system: an experimental and theoretical study. NEW J CHEM 2016. [DOI: 10.1039/c6nj00176a] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A very high dielectric constant of Nb doped titania is observed due to both the interfacial effect and formation of complex defect dipoles.
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Affiliation(s)
- Balaji P. Mandal
- Chemistry Division
- Bhabha Atomic Research Centre
- Mumbai – 400085
- India
| | - P. Anithakumari
- Chemistry Division
- Bhabha Atomic Research Centre
- Mumbai – 400085
- India
| | - Sandeep Nigam
- Chemistry Division
- Bhabha Atomic Research Centre
- Mumbai – 400085
- India
| | | | - Manoj Mohapatra
- Radiochemistry Division
- Bhabha Atomic Research Centre
- Mumbai – 400085
- India
| | - Avesh K. Tyagi
- Chemistry Division
- Bhabha Atomic Research Centre
- Mumbai – 400085
- India
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18
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Wang Z, Wen B, Hao Q, Liu LM, Zhou C, Mao X, Lang X, Yin WJ, Dai D, Selloni A, Yang X. Localized Excitation of Ti3+ Ions in the Photoabsorption and Photocatalytic Activity of Reduced Rutile TiO2. J Am Chem Soc 2015; 137:9146-52. [DOI: 10.1021/jacs.5b04483] [Citation(s) in RCA: 142] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Zhiqiang Wang
- State
Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of
Chemical Physics, Chinese Academy of Science, 457 Zhongshan Road, Dalian, 116023, Liaoning, P. R. China
| | - Bo Wen
- Beijing Computational
Science Research Center, Beijing, 100094, P. R. China
- International
Center for Quantum Materials, Peking University, Beijing, 100871, P. R. China
| | - Qunqing Hao
- State
Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of
Chemical Physics, Chinese Academy of Science, 457 Zhongshan Road, Dalian, 116023, Liaoning, P. R. China
| | - Li-Min Liu
- Beijing Computational
Science Research Center, Beijing, 100094, P. R. China
| | - Chuanyao Zhou
- State
Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of
Chemical Physics, Chinese Academy of Science, 457 Zhongshan Road, Dalian, 116023, Liaoning, P. R. China
| | - Xinchun Mao
- State
Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of
Chemical Physics, Chinese Academy of Science, 457 Zhongshan Road, Dalian, 116023, Liaoning, P. R. China
| | - Xiufeng Lang
- Beijing Computational
Science Research Center, Beijing, 100094, P. R. China
| | - Wen-Jin Yin
- Beijing Computational
Science Research Center, Beijing, 100094, P. R. China
- Chengdu Green Energy and Green Manufacturing Technology R&D Center, Chengdu, Sichuan 610207, P. R. China
| | - Dongxu Dai
- State
Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of
Chemical Physics, Chinese Academy of Science, 457 Zhongshan Road, Dalian, 116023, Liaoning, P. R. China
| | - Annabella Selloni
- Department
of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Xueming Yang
- State
Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of
Chemical Physics, Chinese Academy of Science, 457 Zhongshan Road, Dalian, 116023, Liaoning, P. R. China
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Schindler P, Logar M, Provine J, Prinz FB. Enhanced Step Coverage of TiO₂ Deposited on High Aspect Ratio Surfaces by Plasma-Enhanced Atomic Layer Deposition. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:5057-62. [PMID: 25896559 DOI: 10.1021/acs.langmuir.5b00216] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Plasma-enhanced atomic layer deposition (PEALD) provides multiple benefits compared to thermal ALD including lower possible process temperature and a wider palette of possible materials. However, coverage of high aspect ratio (AR) structures is limited due to the recombination rates of the radical plasma species. We study the limits of conformality in 1:30 AR structures for TiO2 based on tetrakis(dimethylamido)titanium (TDMA-Ti) and O2 plasma through variation in plasma exposure and substrate temperature. Extending plasma exposure duration and decreasing substrate temperature within the ALD window both serve to improve the conformality of the deposited film, with coverage >95% achievable. Additionally, the changes in morphology of the TiO2 were examined with crystallites of anatase and brookite found.
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Affiliation(s)
| | - Manca Logar
- ∥Laboratory for Materials Chemistry, National Institute of Chemistry Slovenia, Ljubljana 1000, Slovenia
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20
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Shang C, Zhao WN, Liu ZP. Searching for new TiO₂ crystal phases with better photoactivity. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:134203. [PMID: 25767097 DOI: 10.1088/0953-8984/27/13/134203] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Using the recently developed stochastic surface walking global optimization method, this work explores the potential energy surface of TiO2 crystals aiming to search for likely phases with higher photocatalytic activity. Five new phases of TiO2 are identified and the lowest energy phase transition pathways connecting to the most abundant phases (rutile and anatase) are determined. Theory shows that a high-pressure phase, α-PbO2-like form (TiO2II) acts as the key intermediate in between rutile and anatase. The phase transition of anatase to rutile belongs to the diffusionless Martensitic phase transition, occurring through a set of habit planes, rutile(101)//TiO2II(001), and TiO2II(100)//anatase(112). With regard to the photocatalytic activity, three pure phases (#110, pyrite and fluorite) are found to possess the band gap narrower than rutile, but they are unstable at the low-pressure condition. Instead, a mixed anatase-TiO2II phase is found to have good stability and narrower band gap than both parent phases. Because of the phase separation, the mixed phase is also expected to improve the photocatalytic performance by reducing the probability of the electron-hole pair recombination.
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Affiliation(s)
- Cheng Shang
- Key Laboratory of Computational Physical Science (Ministry of Education), Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Department of Chemistry, Fudan University, Shanghai 200433, China
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21
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Zainullina V, Zhukov V, Korotin M. Influence of oxygen nonstoichiometry and doping with 2p-, 3p-, 6p- and 3d-elements on electronic structure, optical properties and photocatalytic activity of rutile and anatase: Ab initio approaches. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY C-PHOTOCHEMISTRY REVIEWS 2015. [DOI: 10.1016/j.jphotochemrev.2014.10.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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22
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Formation of titanium monoxide (001) single-crystalline thin film induced by ion bombardment of titanium dioxide (110). Nat Commun 2015; 6:6147. [PMID: 25707936 DOI: 10.1038/ncomms7147] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 12/16/2014] [Indexed: 11/09/2022] Open
Abstract
A plethora of technological applications justify why titanium dioxide is probably the most studied oxide, and an optimal exploitation of its properties quite frequently requires a controlled modification of the surface. Low-energy ion bombardment is one of the most extended techniques for this purpose and has been recently used in titanium oxides, among other applications, to favour resistive switching mechanisms or to form transparent conductive layers. Surfaces modified in this way are frequently described as reduced and defective, with a high density of oxygen vacancies. Here we show, at variance with this view, that high ion doses on rutile titanium dioxide (110) induce its transformation into a nanometric and single-crystalline titanium monoxide (001) thin film with rocksalt structure. The discovery of this ability may pave the way to new technical applications of ion bombardment not previously reported, which can be used to fabricate heterostructures and interfaces.
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23
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Meléndez JJ, Zulueta YA, Leyet Y. First-principles study of neutral defects in Fe-doped cubic barium titanate. CERAMICS INTERNATIONAL 2015; 41:1647-1656. [DOI: 10.1016/j.ceramint.2014.09.104] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2024]
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24
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Kapilashrami M, Zhang Y, Liu YS, Hagfeldt A, Guo J. Probing the Optical Property and Electronic Structure of TiO2 Nanomaterials for Renewable Energy Applications. Chem Rev 2014; 114:9662-707. [DOI: 10.1021/cr5000893] [Citation(s) in RCA: 379] [Impact Index Per Article: 37.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Mukes Kapilashrami
- Advanced
Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Yanfeng Zhang
- College
of Chemistry and Material Science, Hebei Normal University, Shijiazhuang, Hebei 050024, People’s Republic of China
| | - Yi-Sheng Liu
- Advanced
Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Anders Hagfeldt
- Physical
Chemistry, Department of Chemistry−Ångström Laboratory, Uppsala University, 751 20 Uppsala, Sweden
| | - Jinghua Guo
- Advanced
Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Department
of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States
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25
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Lee K, Mazare A, Schmuki P. One-dimensional titanium dioxide nanomaterials: nanotubes. Chem Rev 2014; 114:9385-454. [PMID: 25121734 DOI: 10.1021/cr500061m] [Citation(s) in RCA: 506] [Impact Index Per Article: 50.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Kiyoung Lee
- Department of Materials Science WW4-LKO, University of Erlangen-Nuremberg , Martensstrasse 7, 91058 Erlangen, Germany
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26
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Hu W, Liu Y, Withers RL, Frankcombe TJ, Norén L, Snashall A, Kitchin M, Smith P, Gong B, Chen H, Schiemer J, Brink F, Wong-Leung J. Electron-pinned defect-dipoles for high-performance colossal permittivity materials. NATURE MATERIALS 2013; 12:821-826. [PMID: 23812129 DOI: 10.1038/nmat3691] [Citation(s) in RCA: 164] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Accepted: 05/22/2013] [Indexed: 06/02/2023]
Abstract
The immense potential of colossal permittivity (CP) materials for use in modern microelectronics as well as for high-energy-density storage applications has propelled much recent research and development. Despite the discovery of several new classes of CP materials, the development of such materials with the required high performance is still a highly challenging task. Here, we propose a new electron-pinned, defect-dipole route to ideal CP behaviour, where hopping electrons are localized by designated lattice defect states to generate giant defect-dipoles and result in high-performance CP materials. We present a concrete example, (Nb+In) co-doped TiO₂ rutile, that exhibits a largely temperature- and frequency-independent colossal permittivity (> 10(4)) as well as a low dielectric loss (mostly < 0.05) over a very broad temperature range from 80 to 450 K. A systematic defect analysis coupled with density functional theory modelling suggests that 'triangular' In₂(3+)Vo(••)Ti(3+) and 'diamond' shaped Nb₂(5+)Ti(3+)A(Ti) (A = Ti(3+)/In(3+)/Ti(4+)) defect complexes are strongly correlated, giving rise to large defect-dipole clusters containing highly localized electrons that are together responsible for the excellent CP properties observed in co-doped TiO₂. This combined experimental and theoretical work opens up a promising feasible route to the systematic development of new high-performance CP materials via defect engineering.
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Affiliation(s)
- Wanbiao Hu
- Research School of Chemistry, The Australian National University, Australian Capital Territory 0200, Australia
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27
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Novell-Leruth G, Carchini G, López N. On the properties of binary rutile MO2 compounds, M = Ir, Ru, Sn, and Ti: A DFT study. J Chem Phys 2013; 138:194706. [DOI: 10.1063/1.4803854] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
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28
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Fang Y, Cheng D, Niu M, Yi Y, Wu W. Tailoring the electronic and optical properties of rutile TiO2 by (Nb+Sb, C) codoping from DFT+U calculations. Chem Phys Lett 2013. [DOI: 10.1016/j.cplett.2013.02.070] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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29
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Zhang L, Miller BK, Crozier PA. Atomic level in situ observation of surface amorphization in anatase nanocrystals during light irradiation in water vapor. NANO LETTERS 2013; 13:679-684. [PMID: 23294377 DOI: 10.1021/nl304333h] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
An in situ atomic level investigation of the surface structure of anatase nanocrystals has been conducted under conditions relevant to gas phase photocatalytic splitting of water. The experiments were carried out in a modified environmental transmission electron microscope fitted with a high intensity broadband light source with an illumination intensity of 1430 mW/cm(2) close to 10 suns. When the titania is exposed to light and water vapor, the initially crystalline surface converts to an amorphous phase one to two monolayers thick. Spectroscopic analyses show that the amorphous layer contains titanium in a +3 oxidation state. The amorphous layer is stable and does not increase in thickness with time and is heavily hydroxylated. This disorder layer will be present on the anatase surface under reaction conditions relevant to photocatalytic splitting of water.
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Affiliation(s)
- Liuxian Zhang
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona 85287-6106, USA
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30
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Kernazhitsky L, Shymanovska V, Gavrilko T, Naumov V, Kshnyakin V, Khalyavka T. A comparative study of optical absorption and photocatalytic properties of nanocrystalline single-phase anatase and rutile TiO2 doped with transition metal cations. J SOLID STATE CHEM 2013. [DOI: 10.1016/j.jssc.2012.11.015] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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31
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Paramasivam I, Jha H, Liu N, Schmuki P. A review of photocatalysis using self-organized TiO2 nanotubes and other ordered oxide nanostructures. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2012; 8:3073-3103. [PMID: 22961930 DOI: 10.1002/smll.201200564] [Citation(s) in RCA: 316] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Revised: 05/03/2012] [Indexed: 06/01/2023]
Abstract
Photocatalytic approaches, that is the reaction of light-produced charge carriers at a semiconductor surface with their environment, currently attract an extremely wide scientific interest. This is to a large extent due to the high expectations: i) to convert sunlight directly into an energy carrier (H(2)), ii) to stimulate chemical synthetic reactions, or iii) to degrade unwanted environmental pollutants. Since the early reports in 1972, TiO(2) has been the most investigated photocatalytic material by far; this originates from its outstanding electronic properties that allow for a wide range of applications. Not only the material, but also its structure and morphology, can have a considerable influence on the photocatalytic performance of TiO(2). In recent years, particularly 1D (or pseudo 1D) structures such as nanowires and nanotubes have received great attention. The present Review focuses on TiO(2) nanotube arrays (and similar structures) that grow by self-organizing electrochemistry (highly aligned) from a Ti metal substrate. Herein, the growth, properties, and applications of these tubes are discussed, as well as ways and means to modify critical tube properties. Common strategies are addressed to improve the performance of photocatalysts such as doping or band-gap engineering, co-catalyst decoration, junction formation, or applying external bias. Finally, some unique applications of the ordered tube structures in various photocatalytic approaches are outlined.
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Affiliation(s)
- Indhumati Paramasivam
- Department of Materials Science WW4, LKO, University of Erlangen-Nürnberg, Martensstr.7, 91058 Erlangen, Germany
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32
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33
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Paudel HP, Leuenberger MN. Light-controlled plasmon switching using hybrid metal-semiconductor nanostructures. NANO LETTERS 2012; 12:2690-2696. [PMID: 22471346 DOI: 10.1021/nl203990c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We present a proof of concept for the dynamic control over the plasmon resonance frequencies in a hybrid metal-semiconductor nanoshell structure with Ag core and TiO(2) coating. Our method relies on the temporary change of the dielectric function ε of TiO(2) achieved through temporarily generated electron-hole pairs by means of a pump laser pulse. This change in ε leads to a blue shift of the Ag surface plasmon frequency. We choose TiO(2) as the environment of the Ag core because the band gap energy of TiO(2) is larger than the Ag surface plasmon energy of our nanoparticles, which allows the surface plasmon being excited without generating electron-hole pairs in the environment at the same time. We calculate the magnitude of the plasmon resonance shift as a function of electron-hole pair density and obtain shifts up to 126 nm at wavelengths around 460 nm. Using our results, we develop the model of a light-controlled surface plasmon polariton switch.
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Affiliation(s)
- Hari P Paudel
- NanoScience Technology Center and Department of Physics, University of Central Florida, 12424 Research Parkway Suite 400, Orlando, Florida 32826, United States
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34
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Landmann M, Rauls E, Schmidt WG. The electronic structure and optical response of rutile, anatase and brookite TiO2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:195503. [PMID: 22517072 DOI: 10.1088/0953-8984/24/19/195503] [Citation(s) in RCA: 133] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
In this study, we present a combined density functional theory and many-body perturbation theory study on the electronic and optical properties of TiO(2) brookite as well as the tetragonal phases rutile and anatase. The electronic structure and linear optical response have been calculated from the Kohn-Sham band structure applying (semi)local as well as nonlocal screened hybrid exchange-correlation density functionals. Single-particle excitations are treated within the GW approximation for independent quasiparticles. For optical response calculations, two-particle excitations have been included by solving the Bethe-Salpeter equation for Coulomb correlated electron-hole pairs. On this methodological basis, gap data and optical spectra for the three major phases of TiO(2) are provided. The common characteristics of brookite with the rutile and anatase phases, which have been discussed more comprehensively in the literature, are highlighted. Furthermore, the comparison of the present calculations with measured optical response data of rutile indicate that discrepancies discussed in numerous earlier studies are due to the measurements rather than related to an insufficient theoretical description.
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Affiliation(s)
- M Landmann
- Lehrstuhl für Theoretische Physik, Universität Paderborn, Paderborn, Germany.
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35
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36
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Yu X, Hou T, Sun X, Li Y. The Influence of Defects on Mo-Doped TiO2 by First-Principles Studies. Chemphyschem 2012; 13:1514-21. [DOI: 10.1002/cphc.201101012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 02/10/2012] [Indexed: 11/08/2022]
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37
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Khoa Le T, Flahaut D, Foix D, Blanc S, Hung Nguyen HK, Xuan Huynh TK, Martinez H. Study of surface fluorination of photocatalytic TiO2 by thermal shock method. J SOLID STATE CHEM 2012. [DOI: 10.1016/j.jssc.2012.01.034] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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38
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Lavrentyev AA, Gabrelian BV, Shkumat PN, Nikiforov IY, Zavaliy IY, Izvekov AV, Khyzhun OY. Electronic structure of Ti4Fe2O as determined from ab initio calculations and X-ray spectroscopy studies. J STRUCT CHEM+ 2012. [DOI: 10.1134/s0022476611070079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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39
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Chiodo L, Salazar M, Romero AH, Laricchia S, Sala FD, Rubio A. Structure, electronic, and optical properties of TiO2 atomic clusters: An ab initio study. J Chem Phys 2011; 135:244704. [DOI: 10.1063/1.3668085] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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40
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Wu BB, Pan FM, Yang YE. Annealing Effect of Pulsed Laser Deposited Transparent Conductive Ta-Doped Titanium Oxide Films. CHINESE PHYSICS LETTERS 2011; 28:118102. [DOI: 10.1088/0256-307x/28/11/118102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
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41
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Magyari-Köpe B, Tendulkar M, Park SG, Lee HD, Nishi Y. Resistive switching mechanisms in random access memory devices incorporating transition metal oxides: TiO2, NiO and Pr0.7Ca0.3MnO3. NANOTECHNOLOGY 2011; 22:254029. [PMID: 21572196 DOI: 10.1088/0957-4484/22/25/254029] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Resistance change random access memory (RRAM) cells, typically built as MIM capacitor structures, consist of insulating layers I sandwiched between metal layers M, where the insulator performs the resistance switching operation. These devices can be electrically switched between two or more stable resistance states at a speed of nanoseconds, with long retention times, high switching endurance, low read voltage, and large switching windows. They are attractive candidates for next-generation non-volatile memory, particularly as a flash successor, as the material properties can be scaled to the nanometer regime. Several resistance switching models have been suggested so far for transition metal oxide based devices, such as charge trapping, conductive filament formation, Schottky barrier modulation, and electrochemical migration of point defects. The underlying fundamental principles of the switching mechanism still lack a detailed understanding, i.e. how to control and modulate the electrical characteristics of devices incorporating defects and impurities, such as oxygen vacancies, metal interstitials, hydrogen, and other metallic atoms acting as dopants. In this paper, state of the art ab initio theoretical methods are employed to understand the effects that filamentary types of stable oxygen vacancy configurations in TiO(2) and NiO have on the electronic conduction. It is shown that strong electronic interactions between metal ions adjacent to oxygen vacancy sites results in the formation of a conductive path and thus can explain the 'ON' site conduction in these materials. Implication of hydrogen doping on electroforming is discussed for Pr(0.7)Ca(0.3)MnO(3) devices based on electrical characterization and FTIR measurements.
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42
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Taylor DJ, Paterson MJ. Calculations of the low-lying excited states of the TiO(2) molecule. J Chem Phys 2011; 133:204302. [PMID: 21133439 DOI: 10.1063/1.3515477] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
We present calculations of the lowest excited electronic states of the TiO(2) molecule. These are computed using several correlated wavefunction response based methods, as well as time-dependent density functional response theory using a range of functionals. Surprisingly lower cost wavefunction based methods, in particular the second-order CC2 and CIS(D) methods, completely fail to describe the lowest (1)B(2) and (1)A(2) states of the molecule. Density functional methods fare better but still show considerable variation amongst functionals. Thus TiO(2) provides a strenuous test for correlated excited state methods.
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Affiliation(s)
- Daniel J Taylor
- Department of Chemistry, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, Scotland
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43
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Pyrgiotakis G, Lee SH, Sigmund W. Advanced Photocatalysis with Anatase Nano-coated Multi-walled Carbon Nanotubes. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-876-r5.7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AbstractA novel approach is presented to synergistically enhance photocatalytic activity in a nanocomposite using the high aspect ratio of carbon nanotube (CNT) and their unique electrical properties. Composite nanoparticles were synthesized with sol-gel nano-coating on multi-walled carbon nanotubes (MWNTs). The nanostructure was characterized using SEM, TEM, XRD, Raman, FTIR and UV-VIS spectroscopies. Photocatalytic efficiencies of commercial photocatalysts (Degussa P25) and TiO2 nano-coated MWNTs were evaluated by Azo dye degradation tests. Superior photocatalytic activity was observed for the nanocomposite with UV-A and with visible light only irradiation.
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44
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Tian H, Schryvers D, Liu D, Jiang Q, Van Humbeeck J. Stability of Ni in nitinol oxide surfaces. Acta Biomater 2011; 7:892-9. [PMID: 20849983 DOI: 10.1016/j.actbio.2010.09.009] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Revised: 09/04/2010] [Accepted: 09/08/2010] [Indexed: 11/18/2022]
Abstract
The stability of Ni in titanium oxide surface layers on nitinol wires known to release certain amounts of Ni was investigated by first principles density functional theory and transmission electron microscopy. The oxides were identified as a combination of TiO and TiO(2) depending on the thickness of the layer. The calculations indicate that free Ni atoms can exist in TiO at ambient temperature while Ni particles form in TiO(2), which was confirmed by the transmission electron microscopy observations. The results are discussed with respect to surface stability and Ni release due to free Ni atoms and Ni particles.
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Affiliation(s)
- He Tian
- EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium
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45
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Wu CW, Lu CW, Lee YP, Wu YJ, Cheng BM, Lin MC. Blue/near UV light emission from hybrid InN/TiO2 nanoparticle films. ACTA ACUST UNITED AC 2011. [DOI: 10.1039/c1jm11437a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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46
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Yildirim G, Akdogan M, Varilci A, Terzioglu C. Role of annealing environment and partial pressure on structure and optical performance of TiO2 thin films fabricated by rf sputter method. CRYSTAL RESEARCH AND TECHNOLOGY 2010. [DOI: 10.1002/crat.201000464] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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47
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Kars İ, Çetin SŞ, Kınacı B, Sarıkavak B, Bengi A, Altuntaş H, Öztürk MK, Özçelik S. Influence of thermal annealing on the structure and optical properties of d.c. magnetron sputtered titanium dioxide thin films. SURF INTERFACE ANAL 2010. [DOI: 10.1002/sia.3373] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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48
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Fox H, Newman KE, Schneider WF, Corcelli SA. Bulk and Surface Properties of Rutile TiO2 from Self-Consistent-Charge Density Functional Tight Binding. J Chem Theory Comput 2010; 6:499-507. [DOI: 10.1021/ct900665a] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- H. Fox
- Department of Chemistry and Biochemistry, Department of Physics, Department of Chemical and Biomolecular Engineering, and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
| | - K. E. Newman
- Department of Chemistry and Biochemistry, Department of Physics, Department of Chemical and Biomolecular Engineering, and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
| | - W. F. Schneider
- Department of Chemistry and Biochemistry, Department of Physics, Department of Chemical and Biomolecular Engineering, and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
| | - S. A. Corcelli
- Department of Chemistry and Biochemistry, Department of Physics, Department of Chemical and Biomolecular Engineering, and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
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Shojaee E, Mohammadizadeh MR. First-principles elastic and thermal properties of TiO2: a phonon approach. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:015401. [PMID: 21386223 DOI: 10.1088/0953-8984/22/1/015401] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Elastic and thermal properties of the TiO(2) lattice in anatase and rutile phases were studied in the framework of density functional perturbation theory within the local density approximation (LDA) and generalized-gradient approximation (GGA). The full elastic constant tensors of the polymorphs were calculated by linear fits to the acoustic branches of the phonon band structure near the center of the first Brillouin zone in symmetry directions of the crystals. It was observed that the elastic constants within the GGA are in better agreement with experiment. In addition, the Born effective charges, dielectric tensor, heat capacity, mean sound velocity and Debye temperature were calculated. The heat capacity at room temperature and the Debye temperature within the LDA are in better agreement with the experimental results. Therefore, using the phonon band structure and the density of states, one can obtain the important mechanical and thermal properties of materials.
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Affiliation(s)
- E Shojaee
- Superconductivity Research Laboratory (SRL), Department of Physics, University of Tehran, Tehran, Iran
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50
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Serpone N, Emeline AV, Kuznetsov VN, Ryabchuk VK. Second Generation Visible-Light-Active Photocatalysts: Preparation, Optical Properties, and Consequences of Dopants on the Band Gap Energy of TiO2. NANOSTRUCTURE SCIENCE AND TECHNOLOGY 2010. [DOI: 10.1007/978-0-387-48444-0_3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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