1
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Rostami M, Yang B, Ma X, You S, Zhou J, Zhang M, Cui X, Zhang H, Allegretti F, Wang B, Chi L, Barth JV. Catalytic effects of iron adatoms in poly( para-phenylene) synthesis on rutile TiO 2(110). NANOSCALE 2025. [PMID: 39817853 DOI: 10.1039/d4nr04407j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2025]
Abstract
n-Armchair graphene nanoribbons (nAGNRs) are promising components for next-generation nanoelectronics due to their controllable band gap, which depends on their width and edge structure. Using non-metal surfaces for fabricating nAGNRs gives access to reliable information on their electronic properties. We investigated the influence of light and iron adatoms on the debromination of 4,4''-dibromo-p-terphenyl precursors affording poly(para-phenylene) (PPP as the narrowest GNR) wires through the Ullmann coupling reaction on a rutile TiO2(110) surface, which we studied by scanning tunneling microscopy and X-ray photoemission spectroscopy. The temperature threshold for bromine bond cleavage and desorption is reduced upon exposure to UV light (240-395 nm wavelength), but the reaction yield could not be improved. However, in the presence of codeposited iron adatoms, precursor debromination occurred even at 77 K, allowing for Ullmann coupling and PPP wire formation at 300-400 K, i.e., markedly lower temperatures compared to the conditions without iron adatoms. Furthermore, scanning tunneling spectroscopy data reveal that adsorbed PPP wires feature a band gap of ≈3.1 eV.
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Affiliation(s)
- Mohammadreza Rostami
- Physics Department E20, School of Natural Sciences, Technical University of Munich, Garching, 85748, Germany.
| | - Biao Yang
- Physics Department E20, School of Natural Sciences, Technical University of Munich, Garching, 85748, Germany.
- Institute of Functional Nano & Soft Materials (FUNSOM), Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, 215123, P. R. China.
| | - Xiaochuan Ma
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information & Quantum Physics, New Cornerstone Science Laboratory, University of Science and Technology of China, Hefei, 230026, China
| | - Sifan You
- Institute of Functional Nano & Soft Materials (FUNSOM), Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, 215123, P. R. China.
| | - Jin Zhou
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information & Quantum Physics, New Cornerstone Science Laboratory, University of Science and Technology of China, Hefei, 230026, China
| | - Meng Zhang
- Institute of Functional Nano & Soft Materials (FUNSOM), Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, 215123, P. R. China.
| | - Xuefeng Cui
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information & Quantum Physics, New Cornerstone Science Laboratory, University of Science and Technology of China, Hefei, 230026, China
| | - Haiming Zhang
- Institute of Functional Nano & Soft Materials (FUNSOM), Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, 215123, P. R. China.
| | - Francesco Allegretti
- Physics Department E20, School of Natural Sciences, Technical University of Munich, Garching, 85748, Germany.
| | - Bing Wang
- Hefei National Research Center for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information & Quantum Physics, New Cornerstone Science Laboratory, University of Science and Technology of China, Hefei, 230026, China
| | - Lifeng Chi
- Institute of Functional Nano & Soft Materials (FUNSOM), Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, Suzhou, 215123, P. R. China.
| | - Johannes V Barth
- Physics Department E20, School of Natural Sciences, Technical University of Munich, Garching, 85748, Germany.
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2
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Redondo J, Reticcioli M, Gabriel V, Wrana D, Ellinger F, Riva M, Franceschi G, Rheinfrank E, Sokolović I, Jakub Z, Kraushofer F, Alexander A, Belas E, Patera LL, Repp J, Schmid M, Diebold U, Parkinson GS, Franchini C, Kocan P, Setvin M. Real-space investigation of polarons in hematite Fe 2O 3. SCIENCE ADVANCES 2024; 10:eadp7833. [PMID: 39485848 PMCID: PMC11529705 DOI: 10.1126/sciadv.adp7833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2024] [Accepted: 09/27/2024] [Indexed: 11/03/2024]
Abstract
In polarizable materials, electronic charge carriers interact with the surrounding ions, leading to quasiparticle behavior. The resulting polarons play a central role in many materials properties including electrical transport, interaction with light, surface reactivity, and magnetoresistance, and polarons are typically investigated indirectly through these macroscopic characteristics. Here, noncontact atomic force microscopy (nc-AFM) is used to directly image polarons in Fe2O3 at the single quasiparticle limit. A combination of Kelvin probe force microscopy (KPFM) and kinetic Monte Carlo (KMC) simulations shows that the mobility of electron polarons can be markedly increased by Ti doping. Density functional theory (DFT) calculations indicate that a transition from polaronic to metastable free-carrier states can play a key role in migration of electron polarons. In contrast, hole polarons are significantly less mobile, and their hopping is hampered further by trapping centers.
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Affiliation(s)
- Jesus Redondo
- Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, 180 00 Prague, Czech Republic
- Institute of Applied Physics, TU Wien, 1040 Vienna, Austria
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 162 00 Prague 6, Czech Republic
| | - Michele Reticcioli
- University of Vienna, Faculty of Physics, Center for Computational Materials Science, Vienna, Austria
| | - Vit Gabriel
- Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, 180 00 Prague, Czech Republic
| | - Dominik Wrana
- Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, 180 00 Prague, Czech Republic
- Marian Smoluchowski Institute of Physics, Jagiellonian University, 30-348 Krakow, Poland
| | - Florian Ellinger
- University of Vienna, Faculty of Physics, Center for Computational Materials Science, Vienna, Austria
| | - Michele Riva
- Institute of Applied Physics, TU Wien, 1040 Vienna, Austria
| | | | | | - Igor Sokolović
- Institute of Applied Physics, TU Wien, 1040 Vienna, Austria
| | - Zdenek Jakub
- Institute of Applied Physics, TU Wien, 1040 Vienna, Austria
| | | | - Aji Alexander
- Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, 180 00 Prague, Czech Republic
| | - Eduard Belas
- Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, 180 00 Prague, Czech Republic
| | - Laerte L. Patera
- Institute of Experimental and Applied Physics, University of Regensburg, 93040 Regensburg, Germany
- Institute of Physical Chemistry, University of Innsbruck, 6020 Innsbruck, Austria
| | - Jascha Repp
- Institute of Experimental and Applied Physics, University of Regensburg, 93040 Regensburg, Germany
| | - Michael Schmid
- Institute of Applied Physics, TU Wien, 1040 Vienna, Austria
| | - Ulrike Diebold
- Institute of Applied Physics, TU Wien, 1040 Vienna, Austria
| | | | - Cesare Franchini
- University of Vienna, Faculty of Physics, Center for Computational Materials Science, Vienna, Austria
- Dipartimento di Fisica e Astronomia, Università di Bologna, 40127 Bologna, Italy
| | - Pavel Kocan
- Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, 180 00 Prague, Czech Republic
| | - Martin Setvin
- Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, 180 00 Prague, Czech Republic
- Institute of Applied Physics, TU Wien, 1040 Vienna, Austria
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3
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Ryan PT, Sombut P, Rafsanjani-Abbasi A, Wang C, Eratam F, Goto F, Franchini C, Diebold U, Meier M, Duncan DA, Parkinson GS. Quantitative Measurement of Cooperative Binding in Partially Dissociated Water Dimers at the Hematite "R-Cut" Surface. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2024; 128:16977-16985. [PMID: 39416807 PMCID: PMC11481491 DOI: 10.1021/acs.jpcc.4c04537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2024] [Revised: 09/10/2024] [Accepted: 09/11/2024] [Indexed: 10/19/2024]
Abstract
Water-solid interfaces pervade the natural environment and modern technology. On some surfaces, water-water interactions induce the formation of partially dissociated interfacial layers; understanding why is important to model processes in catalysis or mineralogy. The complexity of the partially dissociated structures often makes it difficult to probe them quantitatively. Here, we utilize normal incidence X-ray standing waves (NIXSW) to study the structure of partially dissociated water dimers (H2O-OH) at the α-Fe2O3(012) surface (also called the (11̅02) or "R-cut" surface): a system simple enough to be tractable yet complex enough to capture the essential physics. We find the H2O and terminal OH groups to be the same height above the surface within experimental error (1.45 ± 0.04 and 1.47 ± 0.02 Å, respectively), in line with DFT-based calculations that predict comparable Fe-O bond lengths for both water and OH species. This result is understood in the context of cooperative binding, where the formation of the H-bond between adsorbed H2O and OH induces the H2O to bind more strongly and the OH to bind more weakly compared to when these species are isolated on the surface. The surface OH formed by the liberated proton is found to be in plane with a bulk truncated (012) surface (-0.01 ± 0.02 Å). DFT calculations based on various functionals correctly model the cooperative effect but overestimate the water-surface interaction.
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Affiliation(s)
- Paul T.
P. Ryan
- Institute
of Applied Physics, Technische Universität
Wien, 1040 Vienna, Austria
| | - Panukorn Sombut
- Institute
of Applied Physics, Technische Universität
Wien, 1040 Vienna, Austria
| | | | - Chunlei Wang
- Institute
of Applied Physics, Technische Universität
Wien, 1040 Vienna, Austria
| | - Fulden Eratam
- Diamond
Light Source, Harwell Science and Innovation Campus, OX11 0QX Didcot, U.K.
| | - Francesco Goto
- Diamond
Light Source, Harwell Science and Innovation Campus, OX11 0QX Didcot, U.K.
- Politecnico
di Milano, Piazza Leonardo da Vinci, 20133 Milano MI, Italy
| | - Cesare Franchini
- Faculty
of Physics and Center for Computational Materials Science, University of Vienna, 1040 Vienna, Austria
| | - Ulrike Diebold
- Institute
of Applied Physics, Technische Universität
Wien, 1040 Vienna, Austria
| | - Matthias Meier
- Institute
of Applied Physics, Technische Universität
Wien, 1040 Vienna, Austria
- Faculty
of Physics and Center for Computational Materials Science, University of Vienna, 1040 Vienna, Austria
| | - David A. Duncan
- Diamond
Light Source, Harwell Science and Innovation Campus, OX11 0QX Didcot, U.K.
| | - Gareth S. Parkinson
- Institute
of Applied Physics, Technische Universität
Wien, 1040 Vienna, Austria
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4
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Rafsanjani-Abbasi A, Buchner F, Lewis FJ, Puntscher L, Kraushofer F, Sombut P, Eder M, Pavelec J, Rheinfrank E, Franceschi G, Birschitzky V, Riva M, Franchini C, Schmid M, Diebold U, Meier M, Madsen GKH, Parkinson GS. Digging Its Own Site: Linear Coordination Stabilizes a Pt 1/Fe 2O 3 Single-Atom Catalyst. ACS NANO 2024; 18:26920-26927. [PMID: 39293063 PMCID: PMC11447906 DOI: 10.1021/acsnano.4c08781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/20/2024]
Abstract
Determining the local coordination of the active site is a prerequisite for the reliable modeling of single-atom catalysts (SACs). Obtaining such information is difficult on powder-based systems and much emphasis is placed on density functional theory computations based on idealized low-index surfaces of the support. In this work, we investigate how Pt atoms bind to the (11̅02) facet of α-Fe2O3; a common support material in SACs. Using a combination of scanning tunneling microscopy, X-ray photoelectron spectroscopy, and an extensive computational evolutionary search, we find that Pt atoms significantly reconfigure the support lattice to facilitate a pseudolinear coordination to surface oxygen atoms. Despite breaking three surface Fe-O bonds, this geometry is favored by 0.84 eV over the best configuration involving an unperturbed support. We suggest that the linear O-Pt-O configuration is common in reactive Pt-based SAC systems because it balances thermal stability with the ability to adsorb reactants from the gas phase. Moreover, we conclude that extensive structural searches are necessary to determine realistic active site geometries in single-atom catalysis.
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Affiliation(s)
| | - Florian Buchner
- Institute of Materials Chemistry, TU Wien, Vienna AT 1060, Austria
| | - Faith J Lewis
- Institute of Applied Physics, TU Wien, Vienna AT 1040, Austria
| | - Lena Puntscher
- Institute of Applied Physics, TU Wien, Vienna AT 1040, Austria
| | | | - Panukorn Sombut
- Institute of Applied Physics, TU Wien, Vienna AT 1040, Austria
| | - Moritz Eder
- Institute of Applied Physics, TU Wien, Vienna AT 1040, Austria
| | - Jiří Pavelec
- Institute of Applied Physics, TU Wien, Vienna AT 1040, Austria
| | - Erik Rheinfrank
- Institute of Applied Physics, TU Wien, Vienna AT 1040, Austria
| | | | - Viktor Birschitzky
- Faculty of Physics and Center for Computational Materials Science, University of Vienna, Vienna AT 1090, Austria
| | - Michele Riva
- Institute of Applied Physics, TU Wien, Vienna AT 1040, Austria
| | - Cesare Franchini
- Faculty of Physics and Center for Computational Materials Science, University of Vienna, Vienna AT 1090, Austria
- Dipartimento di Fisica e Astronomia, Università di Bologna, Bologna IT 40126, Italy
| | - Michael Schmid
- Institute of Applied Physics, TU Wien, Vienna AT 1040, Austria
| | - Ulrike Diebold
- Institute of Applied Physics, TU Wien, Vienna AT 1040, Austria
| | - Matthias Meier
- Institute of Applied Physics, TU Wien, Vienna AT 1040, Austria
- Faculty of Physics and Center for Computational Materials Science, University of Vienna, Vienna AT 1090, Austria
| | - Georg K H Madsen
- Institute of Materials Chemistry, TU Wien, Vienna AT 1060, Austria
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5
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Liang Y, Xiang Y, Wei Z, Avena M, Xiong J, Hou J, Wang M, Tan W. Complexation mechanism of Pb 2+ on Al-substituted hematite: A modeling study and theoretical calculation. ENVIRONMENTAL RESEARCH 2024; 252:118935. [PMID: 38621630 DOI: 10.1016/j.envres.2024.118935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2023] [Revised: 03/21/2024] [Accepted: 04/12/2024] [Indexed: 04/17/2024]
Abstract
Hematite nanoparticles commonly undergoes isomorphic substitution of Al3+ in nature, while how the Al-substitution-induced morphological change, defective structure and newly generated Al-OH sites affect the adsorption behavior of hematite for contaminants remains poorly understood. Herein, the interfacial reactions between Al-substituted hematite and Pb2+ was investigated via CD-MUSIC modeling and DFT calculations. As the Al content increased from 0% to 9.4%, Al-substitution promoted the proportion of (001) facets and caused Fe vacancies on hematite, which increased the total active site density of hematite from 5.60 to 17.60 sites/nm2. The surface positive charge of hematite significantly increased from 0.096 to 0.418 C/m2 at pH 5.0 due to the increases in site density and proton affinity (logKH) of hematite under Al-substitution. The adsorption amount of hematite for Pb2+ increased from 3.92 to 9.74 mmol/kg at pH 5.0 and 20 μmol/L initial Pb2+ concentration with increasing Al content. More Fe vacancies may lead to a weaker adsorption energy (Ead) of hematite for Pb2+, while the Ead was enhanced at higher Al content. The adsorption affinity (logKPb) of bidentate Pb complexes slightly increased while that of tridentate Pb complexes decreased with increasing Al content due to the presence of ≡ AlOH-0.5 and ≡ Fe2AlO-0.5 sites. Tridentate Pb complexes were dominant species on the surface of pure hematite, while bidentate ones became more dominant with increasing Al content. The obtained model parameters and molecular scale information are of great importance for better describing and predicting the environmental fate of toxic heavy metals in terrestrial and aquatic environments.
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Affiliation(s)
- Yu Liang
- Tropical Crops Genetic Resources Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou, 571101, China; State Environmental Protection Key Laboratory of Soil Health and Green Remediation, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
| | - Yongjin Xiang
- State Environmental Protection Key Laboratory of Soil Health and Green Remediation, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
| | - Zhiyuan Wei
- Tropical Crops Genetic Resources Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou, 571101, China
| | - Marcelo Avena
- INQUISUR, Departamento de Química, Universidad Nacional del Sur (UNS)-CONICET, Av. Alem 1253, B8000CPB, Bahía Blanca, Argentina
| | - Juan Xiong
- State Environmental Protection Key Laboratory of Soil Health and Green Remediation, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
| | - Jingtao Hou
- State Environmental Protection Key Laboratory of Soil Health and Green Remediation, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
| | - Mingxia Wang
- State Environmental Protection Key Laboratory of Soil Health and Green Remediation, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
| | - Wenfeng Tan
- State Environmental Protection Key Laboratory of Soil Health and Green Remediation, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China.
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6
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Gu J, Yang S, Liu JZ, Zhang L. Unravelling the atomistic mechanisms underpinning the morphological evolution of Al-alloyed hematite. NANOSCALE 2024; 16:5976-5987. [PMID: 38376499 DOI: 10.1039/d3nr05765h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/21/2024]
Abstract
Hydrothermal synthesis based upon the use of Al3+ as the dopant and/or ethanol as the solvent is effective in promoting the growth of hematite into nanoplates rich in the (001) surface, which is highly active for a broad range of catalytic applications. However, the underpinning mechanism for the flattening of hematite crystals is still poorly comprehended. To close this knowledge gap, in this work, we have attempted intensive computational modelling to construct a binary phase diagram for Fe2O3-Al2O3 under typical hydrothermal conditions, as well as to quantify the surface energy of hematite crystal upon coverage with Al3+ and ethanol molecules. An innovative coupling of density functional theory calculation, cluster expansion and Monte Carlo simulations in analogy to machine learning and prediction was attempted. Upon successful validation by experimental observation, our simulation results suggest an optimum atomic dispersion of Al3+ within hematite in cases when its concentration is below 4 at% otherwise phase separation occurs, and discrete Al2O3 nano-clusters can be preferentially formed. Computations also revealed that the adsorption of ethanol molecules alone can reduce the specific surface energy of the hematite (001) surface from 1.33 to 0.31 J m-2. The segregation of Al3+ on the (001) surface can further reduce the specific surface energy to 0.18 J m-2. Consequently, the (001) surface growth is inhibited, and it becomes dominant after the disappearance of other surfaces upon their continual growth. This work provides atomistic insights into the synergistic effect between the aluminium textural promoter and the ethanol capping agent in determining the morphology of hematite nanoparticles. The established computation approach also applies to other oxide-based catalysts in controlling their surface growth and morphology, which are critical for their catalytic applications.
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Affiliation(s)
- Jinxing Gu
- Department of Chemical and Biological Engineering, Monash University, Victoria, 3800, Australia.
| | - Sasha Yang
- Department of Chemical and Biological Engineering, Monash University, Victoria, 3800, Australia.
| | - Jefferson Zhe Liu
- Department of Mechanical Engineering, Faculty of Engineering and Information Technology, The University of Melbourne, Victoria, 3010, Australia.
| | - Lian Zhang
- Department of Chemical and Biological Engineering, Monash University, Victoria, 3800, Australia.
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7
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Liu S, Li T, Shi F, Ma H, Wang B, Dai X, Cui X. Constructing multiple active sites in iron oxide catalysts for improving carbonylation reactions. Nat Commun 2023; 14:4973. [PMID: 37591841 PMCID: PMC10435489 DOI: 10.1038/s41467-023-40640-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 08/04/2023] [Indexed: 08/19/2023] Open
Abstract
Surface engineering is a promising strategy to improve the catalytic activities of heterogeneous catalysts. Nevertheless, few studies have been devoted to investigate the catalytic behavior differences of the multiple metal active sites triggered by the surface imperfections on catalysis. Herein, oxygen vacancies induced Fe2O3 catalyst are demonstrated with different Fe sites around one oxygen vacancy and exhibited significant catalytic performance for the carbonylation of various aryl halides and amines/alcohols with CO. The developed catalytic system displays excellent activity, selectivity, and reusability for the synthesis of carbonylated chemicals, including drugs and chiral molecules, via aminocarbonylation and alkoxycarbonylation. Combined characterizations disclose the formation of oxygen vacancies. Control experiments and density functional theory calculations demonstrate the selective combination of the three Fe sites is vital to improve the catalytic performance by catalyzing the elemental steps of PhI activation, CO insertion and C-N/C-O coupling respectively, endowing combinatorial sites catalyst for multistep reactions.
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Affiliation(s)
- Shujuan Liu
- State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, No. 18, Tianshui Middle Road, Lanzhou, 730000, China
| | - Teng Li
- State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, No. 18, Tianshui Middle Road, Lanzhou, 730000, China
| | - Feng Shi
- State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, No. 18, Tianshui Middle Road, Lanzhou, 730000, China
| | - Haiying Ma
- State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, No. 18, Tianshui Middle Road, Lanzhou, 730000, China
- University of Chinese Academy of Sciences, No. 19A, Yuquan Road, Beijing, 100049, China
| | - Bin Wang
- State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, No. 18, Tianshui Middle Road, Lanzhou, 730000, China
| | - Xingchao Dai
- State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, No. 18, Tianshui Middle Road, Lanzhou, 730000, China
| | - Xinjiang Cui
- State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, No. 18, Tianshui Middle Road, Lanzhou, 730000, China.
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8
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Photocatalytic Properties of ZnO:Al/MAPbI3/Fe2O3 Heterostructure: First-Principles Calculations. Int J Mol Sci 2023; 24:ijms24054856. [PMID: 36902284 PMCID: PMC10002523 DOI: 10.3390/ijms24054856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Revised: 01/21/2023] [Accepted: 01/30/2023] [Indexed: 03/06/2023] Open
Abstract
We report on theoretical investigations of a methylammonium lead halide perovskite system loaded with iron oxide and aluminum zinc oxide (ZnO:Al/MAPbI3/Fe2O3) as a potential photocatalyst. When excited with visible light, this heterostructure is demonstrated to achieve a high hydrogen production yield via a z-scheme photocatalysis mechanism. The Fe2O3: MAPbI3 heterojunction plays the role of an electron donor, favoring the hydrogen evolution reaction (HER), and the ZnO:Al compound acts as a shield against ions, preventing the surface degradation of MAPbI3 during the reaction, hence improving the charge transfer in the electrolyte. Moreover, our findings indicate that the ZnO:Al/MAPbI3 heterostructure effectively enhances electrons/holes separation and reduces their recombination, which drastically improves the photocatalytic activity. Based on our calculations, our heterostructure yields a high hydrogen production rate, estimated to be 265.05 μmol/g and 362.99 μmol/g, respectively, for a neutral pH and an acidic pH of 5. These theoretical yield values are very promising and provide interesting inputs for the development of stable halide perovskites known for their superlative photocatalytic properties.
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9
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Lahiri N, Song D, Zhang X, Huang X, Stoerzinger KA, Carvalho OQ, Adiga PP, Blum M, Rosso KM. Interplay between Facets and Defects during the Dissociative and Molecular Adsorption of Water on Metal Oxide Surfaces. J Am Chem Soc 2023; 145:2930-2940. [PMID: 36696237 DOI: 10.1021/jacs.2c11291] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Surface terminations and defects play a central role in determining how water interacts with metal oxides, thereby setting important properties of the interface that govern reactivity such as the type and distribution of hydroxyl groups. However, the interconnections between facets and defects remain poorly understood. This limits the usefulness of conventional notions such as that hydroxylation is controlled by metal cation exposure at the surface. Here, using hematite (α-Fe2O3) as a model system, we show how oxygen vacancies overwhelm surface cation-dependent hydroxylation behavior. Synchrotron-based ambient-pressure X-ray photoelectron spectroscopy was used to monitor the adsorption of molecular water and its dissociation to form hydroxyl groups in situ on (001), (012), or (104) facet-engineered hematite nanoparticles. Supported by density functional theory calculations of the respective surface energies and oxygen vacancy formation energies, the findings show how oxygen vacancies are more prone to form on higher energy facets and induce surface hydroxylation at extremely low relative humidity values of 5 × 10-5%. When these vacancies are eliminated, the extent of surface hydroxylation across the facets is as expected from the areal density of exposed iron cations at the surface. These findings help answer fundamental questions about the nature of reducible metal oxide-water interfaces in natural and technological settings and lay the groundwork for rational design of improved oxide-based catalysts.
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Affiliation(s)
- Nabajit Lahiri
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington99352, United States
| | - Duo Song
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington99352, United States
| | - Xin Zhang
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington99352, United States
| | - Xiaopeng Huang
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington99352, United States
| | - Kelsey A Stoerzinger
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington99352, United States.,Department of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, Oregon97331, United States
| | - O Quinn Carvalho
- Department of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, Oregon97331, United States
| | - Prajwal P Adiga
- Department of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, Oregon97331, United States
| | - Monika Blum
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
| | - Kevin M Rosso
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington99352, United States
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10
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Lin J, Ruan L, Wu J, Yang W, Huang X, Huang Z, Ying S, Lin Z. Design and synthesis of yolk-shell Fe 2O 3/N-doped carbon nanospindles with rich oxygen vacancies for robust lithium storage. Phys Chem Chem Phys 2022; 24:29520-29527. [PMID: 36448469 DOI: 10.1039/d2cp03309g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Ferric oxide (Fe2O3) is an attractive anode material for lithium-ion batteries (LIBs) with a high theoretical capacity of 1005 mA h g-1. However, its practical application is greatly restrained by the rapid capacity fading caused by the large volume expansion upon lithiation. To address this issue, we have designed and synthesized a unique yolk-shell Fe2O3/N-doped carbon hybrid structure (YS-Fe2O3@NC) with rich oxygen vacancies for robust lithium storage. The obtained results show that YS-Fe2O3@NC delivers a high reversible capacity of 578 mA h g-1 after 300 cycles at a current density of 5 A g-1, about 11 times that (53.7 mA h g-1) of pristine Fe2O3. Furthermore, a high specific capacity of 300.5 mA h g-1 even at 10 A g-1 is achieved. The high reversible capacities, excellent rate capability and cycle stability of YS-Fe2O3@NC might be attributed to the elaborate yolk-shell nanoarchitecture. Moreover, electron percolation and a local built-in electric field induced by oxygen vacancies in the Fe2O3 matrix could also enhance the kinetics of Li+ insertion/deinsertion.
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Affiliation(s)
- Jianping Lin
- College of mathematics and Physics, Ningde Normal University, Ningde, 352100, China.
| | - Lingfang Ruan
- College of Chemistry and Materials, Ningde Normal University, Fujian Provincial Key Laboratory of Featured Materials in Biochemical Industry, Ningde, 352100, China
| | - Jiasheng Wu
- College of Chemistry and Materials, Ningde Normal University, Fujian Provincial Key Laboratory of Featured Materials in Biochemical Industry, Ningde, 352100, China
| | - Wenyu Yang
- College of mathematics and Physics, Ningde Normal University, Ningde, 352100, China.
| | - Xiaohui Huang
- College of Chemistry and Materials, Ningde Normal University, Fujian Provincial Key Laboratory of Featured Materials in Biochemical Industry, Ningde, 352100, China
| | - Zhiqiang Huang
- College of Chemistry and Materials, Ningde Normal University, Fujian Provincial Key Laboratory of Featured Materials in Biochemical Industry, Ningde, 352100, China
| | - Shaoming Ying
- College of Chemistry and Materials, Ningde Normal University, Fujian Provincial Key Laboratory of Featured Materials in Biochemical Industry, Ningde, 352100, China
| | - Zhiya Lin
- College of mathematics and Physics, Ningde Normal University, Ningde, 352100, China. .,College of Physics and Energy, Fujian Normal University, Fujian Provincial Solar Energy Conversion and Energy Storage Engineering Technology Research Center, Fuzhou, 350117, China
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11
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Ramprasath R, Pragasan LA, Manikandan V, Sudha S, Cholan S, Alarfaj AA, Hirad AH, Gokul B, Sampath S. Visible light photocatalytic and magnetic properties of V doped α-Fe 2O 3 (VFO) nanoparticles synthesized by polyol assisted hydrothermal method. CHEMOSPHERE 2022; 307:135575. [PMID: 35798152 DOI: 10.1016/j.chemosphere.2022.135575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 05/25/2022] [Accepted: 06/29/2022] [Indexed: 06/15/2023]
Abstract
Vanadium-doped α-Fe2O3 nanoparticles (VFO nanoparticles) were prepared by polyol-assisted hydrothermal method. The impact on the structure, optical, magnetic and photocatalytic properties of α-Fe2O3 nanoparticles were studied by varying the vanadium concentration from 1 to 5%. XRD analysis confirms the presence of hematite phase with hexagonal structure and estimates the nanocrystals size as ∼26-38 nm. FESEM and TEM reveal the formation of 3D flower-like morphology bundled with 2D nanoflakes. The estimated band gap energy was in the range 2.01 eV-2.12 eV. XPS study shows the presence of vanadium in V4+ oxidation state in VFO nanoparticles. VSM study shows a non-saturated hysteresis loop with weak ferromagnetic behavior for all the VFO nanoparticles. 5% V doped α-Fe2O3 nanoparticles (5%VFO nanoparticles) exhibited superior visible light driven photocatalytic activity compared to other samples.
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Affiliation(s)
- R Ramprasath
- Department of Physics, Sri Vidya Mandir Arts and Science College, Katteri, Uthangarai, Krishnagiri, 636902, Tamil Nadu, India; Department of Physics, P.D.R.T. Padmavathi Arts and Science College (Women), Dharmapuri, 636902, Tamil Nadu, India
| | - L Arul Pragasan
- Department of Environmental Sciences, Bharathiar University, Coimbatore, 641 046, India
| | - V Manikandan
- Department of BioNano Technology, Gachon University, 1342 Seongnam-daero, Sujeong-gu, Seongnam-si, Gyeonggi-do, 13120, South Korea
| | - S Sudha
- Department of Physics, Sri Vidya Mandir Arts and Science College, Katteri, Uthangarai, Krishnagiri, 636902, Tamil Nadu, India
| | - S Cholan
- Department of Physics, Sri Vidya Mandir Arts and Science College, Katteri, Uthangarai, Krishnagiri, 636902, Tamil Nadu, India; Department of Physics, Gonzaga College of Arts and Science for Women, Krishnagiri, 635108, Tamil Nadu, India.
| | - Abdullah A Alarfaj
- Department of Botany and Microbiology, College of Science, King Saud University, P.O. Box 2455, Riyadh, 11451, Saudi Arabia
| | - Abdurahman Hajinur Hirad
- Department of Botany and Microbiology, College of Science, King Saud University, P.O. Box 2455, Riyadh, 11451, Saudi Arabia
| | - B Gokul
- Department of Physics, Kongunadu Arts and Science College, Coimbatore, 641029, Tamil Nadu, India
| | - Sridhar Sampath
- Department of Physics, Vel Tech Rangarajan Dr. Sagunthala R&D Institute of Science and Technology, Avadi, Chennai, Tamil Nadu, 600062, India
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12
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Hoque MA, Guzman MI, Selegue JP, Gnanamani MK. Chemical State of Potassium on the Surface of Iron Oxides: Effects of Potassium Precursor Concentration and Calcination Temperature. MATERIALS (BASEL, SWITZERLAND) 2022; 15:7378. [PMID: 36295443 PMCID: PMC9610504 DOI: 10.3390/ma15207378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 10/07/2022] [Accepted: 10/19/2022] [Indexed: 06/16/2023]
Abstract
Potassium is used extensively as a promoter with iron catalysts in Fisher-Tropsch synthesis, water-gas shift reactions, steam reforming, and alcohol synthesis. In this paper, the identification of potassium chemical states on the surface of iron catalysts is studied to improve our understanding of the catalytic system. Herein, potassium-doped iron oxide (α-Fe2O3) nanomaterials are synthesized under variable calcination temperatures (400-800 °C) using an incipient wetness impregnation method. The synthesis also varies the content of potassium nitrate deposited on superfine iron oxide with a diameter of 3 nm (Nanocat®) to reach atomic ratios of 100 Fe:x K (x = 0-5). The structure, composition, and properties of the synthesized materials are investigated by X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, Fourier-transform infrared, Raman spectroscopy, inductively coupled plasma-atomic emission spectroscopy, and X-ray photoelectron spectroscopy, as well as transmission electron microscopy, with energy-dispersive X-ray spectroscopy and selected area electron diffraction. The hematite phase of iron oxide retains its structure up to 700 °C without forming any new mixed phase. For compositions as high as 100 Fe:5 K, potassium nitrate remains stable up to 400 °C, but at 500 °C, it starts to decompose into nitrites and, at only 800 °C, it completely decomposes to potassium oxide (K2O) and a mixed phase, K2Fe22O34. The doping of potassium nitrate on the surface of α-Fe2O3 provides a new material with potential applications in Fisher-Tropsch catalysis, photocatalysis, and photoelectrochemical processes.
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Affiliation(s)
- Md. Ariful Hoque
- Department of Chemistry, University of Kentucky, Lexington, KY 40506, USA
| | - Marcelo I. Guzman
- Department of Chemistry, University of Kentucky, Lexington, KY 40506, USA
| | - John P. Selegue
- Department of Chemistry, University of Kentucky, Lexington, KY 40506, USA
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13
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Jin X, Wu D, Liu C, Huang S, Zhou Z, Wu H, Chen X, Huang M, Zhou S, Gu C. Facet effect of hematite on the hydrolysis of phthalate esters under ambient humidity conditions. Nat Commun 2022; 13:6125. [PMID: 36253413 PMCID: PMC9576771 DOI: 10.1038/s41467-022-33950-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 10/07/2022] [Indexed: 12/24/2022] Open
Abstract
Phthalate esters (PAEs) have been extensively used as additives in plastics and wallcovering, causing severe environmental contamination and increasing public health concerns. Here, we find that hematite nanoparticles with specific facet-control can efficiently catalyze PAEs hydrolysis under ambient humidity conditions, with the hydrolysis rates 2 orders of magnitude higher than that in water saturated condition. The catalytic performance of hematite shows a significant facet-dependence with the reactivity in the order {012} > {104} ≫ {001}, related to the atomic array of surface undercoordinated Fe. The {012} and {104} facets with the proper neighboring Fe-Fe distance of 0.34-0.39 nm can bidentately coordinate with PAEs, and thus induce much stronger Lewis-acid catalysis. Our study may inspire the development of nanomaterials with appropriate surface atomic arrays, improves our understanding for the natural transformation of PAEs under low humidity environment, and provides a promising approach to remediate/purify the ambient air contaminated by PAEs.
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Affiliation(s)
- Xin Jin
- grid.41156.370000 0001 2314 964XState Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, 210023 Nanjing, China
| | - Dingding Wu
- grid.41156.370000 0001 2314 964XState Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, 210023 Nanjing, China
| | - Cun Liu
- grid.9227.e0000000119573309Institute of Soil Science, Chinese Academy of Sciences, 210008 Nanjing, China
| | - Shuhan Huang
- grid.41156.370000 0001 2314 964XState Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, 210023 Nanjing, China
| | - Ziyan Zhou
- grid.41156.370000 0001 2314 964XState Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, 210023 Nanjing, China
| | - Hao Wu
- grid.41156.370000 0001 2314 964XState Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, 210023 Nanjing, China
| | - Xiru Chen
- grid.41156.370000 0001 2314 964XState Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, 210023 Nanjing, China
| | - Meiying Huang
- grid.9227.e0000000119573309Institute of Soil Science, Chinese Academy of Sciences, 210008 Nanjing, China
| | - Shaoda Zhou
- Nanjing Kaver Scientific Instrument Co. Ltd., 210042 Nanjing, China
| | - Cheng Gu
- grid.41156.370000 0001 2314 964XState Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, 210023 Nanjing, China
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14
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Abstract
The field of single-atom catalysis (SAC) has expanded greatly in recent years. While there has been much success developing new synthesis methods, a fundamental disconnect exists between most experiments and the theoretical computations used to model them. The real catalysts are based on powder supports, which inevitably contain a multitude of different facets, different surface sites, defects, hydroxyl groups, and other contaminants due to the environment. This makes it extremely difficult to determine the structure of the active SAC site using current techniques. To be tractable, computations aimed at modeling SAC utilize periodic boundary conditions and low-index facets of an idealized support. Thus, the reaction barriers and mechanisms determined computationally represent, at best, a plausibility argument, and there is a strong chance that some critical aspect is omitted. One way to better understand what is plausible is by experimental modeling, i.e., comparing the results of computations to experiments based on precisely defined single-crystalline supports prepared in an ultrahigh-vacuum (UHV) environment. In this review, we report the status of the surface-science literature as it pertains to SAC. We focus on experimental work on supports where the site of the metal atom are unambiguously determined from experiment, in particular, the surfaces of rutile and anatase TiO2, the iron oxides Fe2O3 and Fe3O4, as well as CeO2 and MgO. Much of this work is based on scanning probe microscopy in conjunction with spectroscopy, and we highlight the remarkably few studies in which metal atoms are stable on low-index surfaces of typical supports. In the Perspective section, we discuss the possibility for expanding such studies into other relevant supports.
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Affiliation(s)
- Florian Kraushofer
- Institute of Applied Physics, Technische Universitat Wien, 1040 Vienna, Austria
| | - Gareth S. Parkinson
- Institute of Applied Physics, Technische Universitat Wien, 1040 Vienna, Austria
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15
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Yizengaw KW, Abay TA, Ayele DW, Jiang JC. The remarkable performance of a single iridium atom supported on hematite for methane activation: a density functional theory study. RSC Adv 2022; 12:23736-23746. [PMID: 36090430 PMCID: PMC9393768 DOI: 10.1039/d2ra03585e] [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: 06/10/2022] [Accepted: 08/13/2022] [Indexed: 11/21/2022] Open
Abstract
Methane is the major component of natural gas, and it significantly contributes to global warming. In this study, we investigated methane activation on the α-Fe2O3(110) surface and M/α-Fe2O3(110) surfaces (M = Ag, Ir, Cu, or Co) using the density-functional theory (DFT) + U method. Our study shows that the Ir/α-Fe2O3(110) surface is a more effective catalyst for C-H bond activation than other catalyst surfaces. We have applied electron density difference (EDD), density of states (DOS), and Bader charge calculations to confirm the cooperative CH⋯O and agostic interactions between CH4 and the Ir/α-Fe2O3(110) surface. To further modify the reactivity of the Ir/α-Fe2O3(110) surface towards methane activation, we conducted a study of the effect of oxygen vacancy (OV) on C-H activation and CH4 dehydrogenation. In the comparison of pristine α-Fe2O3(110), Ir/α-Fe2O3(110), and Ir/α-Fe2O3(110)-OV surfaces, the Ir/α-Fe2O3(110)-OV surface is the best in terms of CH4 adsorption energy and C-H bond elongation, whereas the Ir/α-Fe2O3(110) surface catalyst has the lowest C-H bond activation barrier for the CH4 molecule. The calculations indicate that the Ir/α-Fe2O3(110)-OV surface could be a candidate catalyst for CH4 dehydrogenation reactions.
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Affiliation(s)
- Kefale Wagaw Yizengaw
- Department of Chemical Engineering, National Taiwan University of Science and Technology Taipei 106 Taiwan
- Faculty of Chemical and Food Engineering, Bahir Dar Institute of Technology, Bahir Dar University Bahir Dar Ethiopia
| | - Tigist Ayalew Abay
- Department of Chemical Engineering, National Taiwan University of Science and Technology Taipei 106 Taiwan
| | - Delele Worku Ayele
- Department of Chemistry, College of Science, Bahir Dar University Bahir Dar Ethiopia
| | - Jyh-Chiang Jiang
- Department of Chemical Engineering, National Taiwan University of Science and Technology Taipei 106 Taiwan
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16
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Fang T, Li L, Liu C, Mitsuzaki N, Chen Z. Effect of the conductive substrate on the photoelectrocatalytic properties of hematite for water splitting. J Photochem Photobiol A Chem 2022. [DOI: 10.1016/j.jphotochem.2022.114226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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17
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Apriandanu DOB, Nomura S, Nakayama S, Tateishi C, Amano F. Effect of two-step annealing on photoelectrochemical properties of hydrothermally prepared Ti-doped Fe2O3 films. Catal Today 2022. [DOI: 10.1016/j.cattod.2022.06.041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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18
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Yang F, Pei J, Zhao H. First-Principles Investigation of Graphene and Fe 2O 3 Catalytic Activity for Decomposition of Ammonium Perchlorate. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:3844-3851. [PMID: 35297643 DOI: 10.1021/acs.langmuir.2c00027] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The employment of catalysts is an effective way to improve ammonium perchlorate (AP) decomposition performance during the combustion of composite solid propellants. Understanding the micromechanism of catalysts at the atomic level, which is hard to be observed by experiments, can help attain more excellent decomposition properties of AP. In this study, first-principles simulations based on density functional theory were used to explore the effect of the graphene catalyst and iron oxide (Fe2O3) catalyst on AP decomposition. Considering the transfer of a H atom during AP decomposition, the most stable adsorption sites for aforementioned catalysts were found: the top of the C atom of the graphene surface with the adsorption energy of -0.378 eV and the top of the Fe atom of the Fe2O3 surface with the adsorption energy of -1.596 eV. On the basis of adsorption results, our transition state calculations indicate that, in comparison to control groups, graphene and Fe2O3 can reduce the activation energy barrier by ∼19 and ∼37%, respectively, to promote AP decomposition with a transfer process of a H atom on the catalyst surface. Our calculations provide a way for explaining the micromechanism of the catalytic activity of graphene and Fe2O3 nanocomposites in AP decomposition and guide experimental applications of graphene and Fe2O3 for catalytic reactions.
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Affiliation(s)
- Fan Yang
- Department of Mechanical Engineering, Tsinghua University, Beijing 100084, People's Republic of China
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, People's Republic of China
| | - Jiayun Pei
- Department of Mechanical Engineering, Tsinghua University, Beijing 100084, People's Republic of China
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, People's Republic of China
| | - Haiyan Zhao
- Department of Mechanical Engineering, Tsinghua University, Beijing 100084, People's Republic of China
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, People's Republic of China
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19
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Sánchez-Grande A, Nguyën HC, Lauwaet K, Rodríguez-Fernández J, Carrasco E, Cirera B, Sun Z, Urgel JI, Miranda R, Lauritsen JV, Gallego JM, López N, Écija D. Electrically Tunable Reactivity of Substrate-Supported Cobalt Oxide Nanocrystals. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2106407. [PMID: 35064636 DOI: 10.1002/smll.202106407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 12/15/2021] [Indexed: 06/14/2023]
Abstract
First-row transition metal oxides are promising materials for catalyzing the oxygen evolution reaction. Surface sensitive techniques provide a unique perspective allowing the study of the structure, adsorption sites, and reactivity of catalysts at the atomic scale, which furnishes rationalization and improves the design of highly efficient catalytic materials. Here, a scanning probe microscopy study complemented by density functional theory on the structural and electronic properties of CoO nanoislands grown on Au(111) is reported. Two distinct phases are observed: The most extended displays a Moiré pattern (α-region), while the less abundant is 1Co:1Au coincidental (β-region). As a result of the surface registry, in the β-region the oxide adlayer is compressed by 9%, increasing the unoccupied local density of states and enhancing the selective water adsorption at low temperature through a cobalt inversion mechanism. Tip-induced voltage pulses irreversibly transform α- into β-regions, thus opening avenues to modify the structure and reactivity of transition metal oxides by external stimuli like electric fields.
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Affiliation(s)
| | - Huu Chuong Nguyën
- Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Tarragona, 43007, Spain
| | | | | | | | | | - Zhaozong Sun
- Interdisciplinary Nanoscience Center, Aarhus University, Aarhus C, DK-8000, Denmark
| | | | - Rodolfo Miranda
- IMDEA Nanociencia., Madrid, 28049, Spain
- Dep. Física de la Materia Condensada, Universidad Autónoma de Madrid, Cantoblanco, Madrid, 28049, Spain
| | - Jeppe V Lauritsen
- Interdisciplinary Nanoscience Center, Aarhus University, Aarhus C, DK-8000, Denmark
| | - José M Gallego
- Instituto de Ciencias Materiales - CSIC, Cantoblanco, Madrid, 28049, Spain
| | - Nuria López
- Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Tarragona, 43007, Spain
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20
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Liu Y, Smith RDL. Differentiating Defects and Their Influence on Hematite Photoanodes Using X-ray Absorption Spectroscopy and Raman Microscopy. ACS APPLIED MATERIALS & INTERFACES 2022; 14:6615-6624. [PMID: 35099916 DOI: 10.1021/acsami.1c20951] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
A high degree of variability in behavior and performance of hematite as photoanodes for the oxygen evolution reaction signifies a need to improve our understanding of the interplay between defects and photoelectrochemical performance. We approach this problem by applying structure-property analysis to a series of hematite samples synthesized under either O2 or N2 environments such that they exhibit highly variable performance for photoelectrocatalytic oxygen evolution. X-ray absorption fine-structure spectroscopy and Raman spectroscopy provide parameters describing the structure of samples across the series. Systematic comparisons of these parameters to those describing photoelectrochemical performance reveal different defects in samples prepared under N2 or O2. Distinct correlations between both the iron oxidation state and charge carrier density with photoelectrocatalytic performance lead to assignment of the primary defects as oxygen vacancies (N2) and iron vacancies (O2). Differences in the structural distortions caused by these defects are seen in correlations between short-range structural parameters and photoelectrochemical behavior. These distortions are readily observed by Raman spectroscopy, suggesting that it may be possible to calibrate the width, energy, and intensity of peaks in Raman spectra to enable direct analysis of defects in hematite photoanodes.
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Affiliation(s)
- Yutong Liu
- Department of Chemistry, University of Waterloo, 200 University Avenue W., Waterloo, Ontario N2L 3G1, Canada
| | - Rodney D L Smith
- Department of Chemistry, University of Waterloo, 200 University Avenue W., Waterloo, Ontario N2L 3G1, Canada
- Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue W., Waterloo, Ontario N2L 3G1, Canada
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21
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Panaritis C, Yan S, Couillard M, Baranova EA. Electrochemical study of the metal-support interaction between FeOx nanoparticles and cobalt oxide support for the reverse water gas shift reaction. J CO2 UTIL 2022. [DOI: 10.1016/j.jcou.2021.101824] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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22
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Kraushofer F, Haager L, Eder M, Rafsanjani-Abbasi A, Jakub Z, Franceschi G, Riva M, Meier M, Schmid M, Diebold U, Parkinson GS. Single Rh Adatoms Stabilized on α-Fe 2O 3(11̅02) by Coadsorbed Water. ACS ENERGY LETTERS 2022; 7:375-380. [PMID: 35059503 PMCID: PMC8762699 DOI: 10.1021/acsenergylett.1c02405] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 12/17/2021] [Indexed: 06/14/2023]
Abstract
Oxide-supported single-atom catalysts are commonly modeled as a metal atom substituting surface cation sites in a low-index surface. Adatoms with dangling bonds will inevitably coordinate molecules from the gas phase, and adsorbates such as water can affect both stability and catalytic activity. Herein, we use scanning tunneling microscopy (STM), noncontact atomic force microscopy (ncAFM), and X-ray photoelectron spectroscopy (XPS) to show that high densities of single Rh adatoms are stabilized on α-Fe2O3(11̅02) in the presence of 2 × 10-8 mbar of water at room temperature, in marked contrast to the rapid sintering observed under UHV conditions. Annealing to 50 °C in UHV desorbs all water from the substrate leaving only the OH groups coordinated to Rh, and high-resolution ncAFM images provide a direct view into the internal structure. We provide direct evidence of the importance of OH ligands in the stability of single atoms and argue that their presence should be assumed when modeling single-atom catalysis systems.
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Affiliation(s)
- Florian Kraushofer
- Institute
of Applied Physics, TU Wien, Wiedner Hauptstraße 8-10/E134, 1040 Wien, Austria
| | - Lena Haager
- Institute
of Applied Physics, TU Wien, Wiedner Hauptstraße 8-10/E134, 1040 Wien, Austria
| | - Moritz Eder
- Chair
of Physical Chemistry & Catalysis Research Center, Technical University of Munich, Lichtenbergstraße 4, 85748 Garching, Germany
| | - Ali Rafsanjani-Abbasi
- Institute
of Applied Physics, TU Wien, Wiedner Hauptstraße 8-10/E134, 1040 Wien, Austria
| | - Zdeněk Jakub
- Institute
of Applied Physics, TU Wien, Wiedner Hauptstraße 8-10/E134, 1040 Wien, Austria
| | - Giada Franceschi
- Institute
of Applied Physics, TU Wien, Wiedner Hauptstraße 8-10/E134, 1040 Wien, Austria
| | - Michele Riva
- Institute
of Applied Physics, TU Wien, Wiedner Hauptstraße 8-10/E134, 1040 Wien, Austria
| | - Matthias Meier
- Institute
of Applied Physics, TU Wien, Wiedner Hauptstraße 8-10/E134, 1040 Wien, Austria
| | - Michael Schmid
- Institute
of Applied Physics, TU Wien, Wiedner Hauptstraße 8-10/E134, 1040 Wien, Austria
| | - Ulrike Diebold
- Institute
of Applied Physics, TU Wien, Wiedner Hauptstraße 8-10/E134, 1040 Wien, Austria
| | - Gareth S. Parkinson
- Institute
of Applied Physics, TU Wien, Wiedner Hauptstraße 8-10/E134, 1040 Wien, Austria
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23
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Zhang C, Chen G, Si Y, Liu M. Surface modeling of photocatalytic materials for water splitting. Phys Chem Chem Phys 2021; 24:1237-1261. [PMID: 34935801 DOI: 10.1039/d1cp04352h] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The photocatalyst surface is central to photocatalytic reactions. However, it has been a challenge to explicitly understand both the surface configuration and the structure-dependent photocatalytic properties at the atomic level. First-principles density functional theory (DFT) calculations provide a versatile method that makes up for the lack of experimental surface studies. In DFT calculations, the initial surface model greatly affects the accuracy of the calculation results. Consequently, establishing a more realistic and more reliable material surface models is undoubtedly the first step and the most important link in theoretical calculations. The aim of this Perspective is to provide a general understanding of the methods for the surface modeling of photocatalytic materials in recent years. We begin with a discussion of the basic theories applied in photocatalytic surface research, followed by an explanation of the importance of surface modeling in photocatalysis. We then elaborate on the advantages and disadvantages of the basic surface model and briefly describe the latest surface modeling methods. Finally, we evaluate the rationality of current surface modeling methods. We summarize this Perspective by prospecting the developing directions of photocatalytic surface research in the future. It is believed that a reasonable surface model should be verified by both experimental characterization and theoretical computation with negative feedback.
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Affiliation(s)
- Chunyang Zhang
- International Research Center for Renewable Energy, State Key Laboratory of Multiphase Flow, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, P. R. China.
| | - Guijun Chen
- International Research Center for Renewable Energy, State Key Laboratory of Multiphase Flow, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, P. R. China.
| | - Yitao Si
- International Research Center for Renewable Energy, State Key Laboratory of Multiphase Flow, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, P. R. China.
| | - Maochang Liu
- International Research Center for Renewable Energy, State Key Laboratory of Multiphase Flow, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, P. R. China. .,Suzhou Academy of Xi'an Jiaotong University, Suzhou, Jiangsu 215123, P. R. China
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24
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Amini A, Fallah A, Sedaghat A, Gholami A, Cheng C, Gupta AR. Natural vs. Synthetic Phosphate as Efficient Heterogeneous Compounds for Synthesis of Quinoxalines. Int J Mol Sci 2021; 22:13665. [PMID: 34948460 PMCID: PMC8704691 DOI: 10.3390/ijms222413665] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 12/17/2021] [Accepted: 12/17/2021] [Indexed: 11/17/2022] Open
Abstract
Natural phosphate (NP) and synthetic fluorapatite phosphate (SFAP) were proposed as stable, inexpensive, readily available and recyclable catalysts for the condensation of 1,2-diamines with 1,2-dicarbonyls in methanol to afford quinoxaline at room temperature. NP provided as high as 92-99% yield for quinoxalines in short reaction times (i.e., 1-45 min), while SFAP created quinoxalines with 87-97% yield in 60-120 min. From the chemical analyses, X-ray fluoresecency, X-ray diffraction, energy dispersive X-ray and Fourier-transform infrared spectroscopy methods, two main phases (CaO, P2O5) appeared in NP together with other low content phases (SiO2, Fe2O3). Compared to other phases, apatite (CaO and P2O5 as Ca10(PO4)6) played a major role in the catalytic activity of NP. SFAP with similar Ca/P atomic ratio showed a relatively lower catalytic activity than NP for the condensation of 1,2-diamine with 1,2-dicarbonyl in methanol at ambient temperature. To investigate the recyclability of catalysts, the surface properties of NP and 6-recycled NP were investigated using scanning electron microscopy, energy dispersive X-ray and Brunauer-Emmett-Teller and Barrett-Joyner-Halenda methods. Some differences were observed in NP and 6-recycled NP's particle size, surface area, the volume and size of pores, and the content of elements; nevertheless, the use-reuse process did not noticeably change the catalytic property of NP.
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Affiliation(s)
- Abbas Amini
- Centre for Infrastructure of Engineering, Bld Z, Locked Bag 1797, Kingswood Campus, Western Sydney University, Penrith, NSW 2751, Australia
- Department of Mechanical Engineering, Australian College of Kuwait, Mishref, Safat 13015, Kuwait;
| | - Azadeh Fallah
- Department of Chemistry, Payame Noor University, Tehran 19395-4697, Iran;
| | - Ahmad Sedaghat
- Department of Mechanical Engineering, Australian College of Kuwait, Mishref, Safat 13015, Kuwait;
| | - Ahmad Gholami
- Pharmaceutical Sciences Research Center, Shiraz University of Medical Sciences, Shiraz 71348-14336, Iran;
- Department of Pharmaceutical Biotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz 71348-14336, Iran
| | - Chun Cheng
- Department of Materials Science and Engineering, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China;
| | - Anju R. Gupta
- Department of Mechanical Engineering, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH 43606, USA;
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25
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Abbaspour Tamijani A, Augustine LJ, Bjorklund JL, Catalano JG, Mason SE. First-principles characterisation and comparison of clean, hydrated, and defect α-Al2O3 and α-Fe2O3 (110) surfaces. MOLECULAR SIMULATION 2021. [DOI: 10.1080/08927022.2021.2009117] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
| | | | | | - Jeffrey G. Catalano
- Department of Earth and Planetary Sciences, Washington University, St. Louis, USA
| | - Sara E. Mason
- Department of Chemistry, University of Iowa, Iowa City, USA
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26
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Jakub Z, Meier M, Kraushofer F, Balajka J, Pavelec J, Schmid M, Franchini C, Diebold U, Parkinson GS. Rapid oxygen exchange between hematite and water vapor. Nat Commun 2021; 12:6488. [PMID: 34759277 PMCID: PMC8580966 DOI: 10.1038/s41467-021-26601-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 10/13/2021] [Indexed: 11/14/2022] Open
Abstract
Oxygen exchange at oxide/liquid and oxide/gas interfaces is important in technology and environmental studies, as it is closely linked to both catalytic activity and material degradation. The atomic-scale details are mostly unknown, however, and are often ascribed to poorly defined defects in the crystal lattice. Here we show that even thermodynamically stable, well-ordered surfaces can be surprisingly reactive. Specifically, we show that all the 3-fold coordinated lattice oxygen atoms on a defect-free single-crystalline "r-cut" ([Formula: see text]) surface of hematite (α-Fe2O3) are exchanged with oxygen from surrounding water vapor within minutes at temperatures below 70 °C, while the atomic-scale surface structure is unperturbed by the process. A similar behavior is observed after liquid-water exposure, but the experimental data clearly show most of the exchange happens during desorption of the final monolayer, not during immersion. Density functional theory computations show that the exchange can happen during on-surface diffusion, where the cost of the lattice oxygen extraction is compensated by the stability of an HO-HOH-OH complex. Such insights into lattice oxygen stability are highly relevant for many research fields ranging from catalysis and hydrogen production to geochemistry and paleoclimatology.
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Affiliation(s)
- Zdenek Jakub
- Institute of Applied Physics, TU Wien, Vienna, Austria
- Central European Institute of Technology (CEITEC), Brno University of Technology, Brno, Czech Republic
| | - Matthias Meier
- Institute of Applied Physics, TU Wien, Vienna, Austria
- University of Vienna, Faculty of Physics and Center for Computational Materials Science, Vienna, Austria
| | | | - Jan Balajka
- Institute of Applied Physics, TU Wien, Vienna, Austria
| | - Jiri Pavelec
- Institute of Applied Physics, TU Wien, Vienna, Austria
| | | | - Cesare Franchini
- University of Vienna, Faculty of Physics and Center for Computational Materials Science, Vienna, Austria
- Alma Mater Studiorum-Università di Bologna, Bologna, Italy
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27
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Sakr NI, Kizilkaya O, Carlson SF, Chan S, Oumnov RA, Catano J, Kurtz RL, Hall RW, Poliakoff ED, Sprunger PT. Formation of Environmentally Persistent Free Radicals (EPFRs) on the Phenol-Dosed α-Fe 2O 3(0001) Surface. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2021; 125:21882-21890. [PMID: 34992708 PMCID: PMC8725784 DOI: 10.1021/acs.jpcc.1c04298] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Environmentally persistent free radicals (EPFRs) are a class of toxic air pollutants that are found to form by the chemisorption of substituted aromatic molecules on the surface of metal oxides. In this study, we employ X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) to perform a temperature-dependent study of phenol adsorption on α-Fe2O3(0001) to probe the radical formation mechanism by monitoring changes in the electronic structure of both the adsorbed phenol and metal oxide substrate. Upon dosing at room temperature, new phenol-derived electronic states have been clearly observed in the UPS spectrum at saturation coverage. However, upon dosing at high temperature (>200 °C), both photoemission techniques have shown distinctive features that strongly suggest electron transfer from adsorbed phenol to Fe2O3 surface atoms and consequent formation of a surface radical. Consistent with the experiment, DFT calculations show that phenoxyl adsorption on the iron oxide surface at RT leads to a minor charge transfer to the adsorbed molecule. The experimental findings at high temperatures agree well with the EPFRs' proposed formation mechanism and can guide future experimental and computational studies.
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Affiliation(s)
- N I Sakr
- Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Orhan Kizilkaya
- Center for Advanced Microstructures and Devices, Louisiana State University, Baton Rouge, Louisiana 70806, United States
| | - Sierra F Carlson
- Department of Natural Sciences and Mathematics, Dominican University of California, San Rafael, California 94901, United States
| | - Simon Chan
- Department of Natural Sciences and Mathematics, Dominican University of California, San Rafael, California 94901, United States
| | - Reuben A Oumnov
- Department of Natural Sciences and Mathematics, Dominican University of California, San Rafael, California 94901, United States
| | - Jaqueline Catano
- Department of Natural Sciences and Mathematics, Dominican University of California, San Rafael, California 94901, United States
| | - Richard L Kurtz
- Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, United States; Center for Advanced Microstructures and Devices, Louisiana State University, Baton Rouge, Louisiana 70806, United States
| | - Randall W Hall
- Department of Natural Sciences and Mathematics, Dominican University of California, San Rafael, California 94901, United States; Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - E D Poliakoff
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Phillip T Sprunger
- Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, United States; Center for Advanced Microstructures and Devices, Louisiana State University, Baton Rouge, Louisiana 70806, United States
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28
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Saha B, Patra AS, Biswas A, Mukherjee AK, Paul I. Interaction of Grafted Dextrin with a Hematite Surface: Effect of Functional Groups and Molecular Weight. ChemistrySelect 2021. [DOI: 10.1002/slct.202102583] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Biswajit Saha
- Research & Development Tata Steel Limited Jamshedpur 831007 India
| | - Abhay S. Patra
- Research & Development Tata Steel Limited Jamshedpur 831007 India
| | - Arijit Biswas
- Research & Development Tata Steel Limited Jamshedpur 831007 India
| | | | - Indrajit Paul
- Pellet Plant Tata Steel Limited Jamshedpur 831007 India
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29
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Saha B, Patra AS, Mukherjee AK, Paul I. Interaction and thermal stability of carboxymethyl cellulose on α-Fe 2O 3(001) surface: ReaxFF molecular dynamics simulations study. J Mol Graph Model 2021; 102:107787. [PMID: 33142262 DOI: 10.1016/j.jmgm.2020.107787] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 10/20/2020] [Accepted: 10/20/2020] [Indexed: 01/11/2023]
Abstract
Reactive (ReaxFF) molecular dynamic simulations were performed to elucidate the nature of interaction between hematite and carboxymethyl cellulose (CMC) considering effect of moisture and temperature. Simulations showed that the presence of moisture prohibited CMC to interact directly with hematite surface. However, the moisture helps to disperse CMC along the hematite surface thus maximizing the interaction. In dry condition, it was found that the negatively charged oxygen present in the functional groups and in CMC backbone (-CH2OCH2-) take part to form chemical bond with the positively charged surface Fe. The bonding interaction with polymer back bone is a new finding from this simulation. The binding energy estimated as -56.2 kcal/mol clearly indicates chemisorption with bond length ∼2.00 Å. Upon heating up the complex in presence of atmospheric oxygen it was observed that CMC decomposed at high temperature rather than desorbed from the surface. This study clearly shows that CMC is a suitable binder for iron ore pelletization and will pave the way for more rationale design of organic binders.
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Affiliation(s)
- Biswajit Saha
- Research & Development, Tata Steel Limited, Jamshedpur, 831007, India.
| | | | | | - Indrajit Paul
- Pellet Plant, Tata Steel Limited, Jamshedpur, 831007, India
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30
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Lindenthal L, Ruh T, Rameshan R, Summerer H, Nenning A, Herzig C, Löffler S, Limbeck A, Opitz AK, Blaha P, Rameshan C. Ca-doped rare earth perovskite materials for tailored exsolution of metal nanoparticles. ACTA CRYSTALLOGRAPHICA SECTION B, STRUCTURAL SCIENCE, CRYSTAL ENGINEERING AND MATERIALS 2020; 76:1055-1070. [PMID: 33289717 DOI: 10.1107/s2052520620013475] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 10/07/2020] [Indexed: 06/12/2023]
Abstract
Perovskite-type oxide materials (nominal composition ABO3) are a very versatile class of materials, and their properties are tuneable by varying and doping A- and B-site cations. When the B-site contains easily reducible cations (e.g. Fe, Co or Ni), these can exsolve under reducing conditions and form metallic nanoparticles on the surface. This process is very interesting as a novel route for the preparation of catalysts, since oxide surfaces decorated with finely dispersed catalytically active (often metallic) nanoparticles are a key requirement for excellent catalyst performance. Five doped perovskites, namely, La0.9Ca0.1FeO3-δ, La0.6Ca0.4FeO3-δ, Nd0.9Ca0.1FeO3-δ, Nd0.6Ca0.4FeO3-δ and Nd0.6Ca0.4Fe0.9Co0.1O3-δ, have been synthesized and characterized by experimental and theoretical methods with respect to their crystal structures, electronic properties, morphology and exsolution behaviour. All are capable of exsolving Fe and/or Co. Special emphasis has been placed on the influence of the A-site elemental composition on structure and exsolution capability. Using Nd instead of La increased structural distortions and, at the same time, hindered exsolution. Increasing the amount of Ca doping also increased distortions and additionally changed the Fe oxidation states, resulting in exsolution being shifted to higher temperatures as well. Using the easily reducible element Co as the B-site dopant significantly facilitated the exsolution process and led to much smaller and homogeneously distributed exsolved particles. Therefore, the Co-doped perovskite is a promising material for applications in catalysis, even more so as Co is catalytically a highly active element. The results show that fine-tuning of the perovskite composition will allow tailored exsolution of nanoparticles, which can be used for highly sophisticated catalyst design.
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Affiliation(s)
- Lorenz Lindenthal
- Institute of Materials Chemistry, TU Wien, Getreidmarkt 9/165, Vienna 1060, Austria
| | - Thomas Ruh
- Institute of Materials Chemistry, TU Wien, Getreidmarkt 9/165, Vienna 1060, Austria
| | - Raffael Rameshan
- Institute of Materials Chemistry, TU Wien, Getreidmarkt 9/165, Vienna 1060, Austria
| | - Harald Summerer
- Institute of Materials Chemistry, TU Wien, Getreidmarkt 9/165, Vienna 1060, Austria
| | - Andreas Nenning
- Institute of Chemical Technologies and Analytics, TU Wien, Getreidmarkt 9/164, Vienna 1060, Austria
| | - Christopher Herzig
- Institute of Chemical Technologies and Analytics, TU Wien, Getreidmarkt 9/164, Vienna 1060, Austria
| | - Stefan Löffler
- USTEM, TU Wien, Wiedner Hauptstraße 8-10/E057-02, Vienna 1060, Austria
| | - Andreas Limbeck
- Institute of Chemical Technologies and Analytics, TU Wien, Getreidmarkt 9/164, Vienna 1060, Austria
| | - Alexander Karl Opitz
- Institute of Chemical Technologies and Analytics, TU Wien, Getreidmarkt 9/164, Vienna 1060, Austria
| | - Peter Blaha
- Institute of Materials Chemistry, TU Wien, Getreidmarkt 9/165, Vienna 1060, Austria
| | - Christoph Rameshan
- Institute of Materials Chemistry, TU Wien, Getreidmarkt 9/165, Vienna 1060, Austria
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31
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Ilunga AK, Mamba BB, Nkambule TT. Methyl orange degradation enhanced by hydrogen spillover onto platinum nanocatalyst surface. Appl Organomet Chem 2020. [DOI: 10.1002/aoc.6050] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Ali K. Ilunga
- Nanotechnology and Water Sustainability (NanoWS) Research Unit University of South Africa (UNISA Science Campus) Florida (Johannesburg) PO Box 392 South Africa
| | - Bhekie B. Mamba
- Nanotechnology and Water Sustainability (NanoWS) Research Unit University of South Africa (UNISA Science Campus) Florida (Johannesburg) PO Box 392 South Africa
| | - Thabo T.I. Nkambule
- Nanotechnology and Water Sustainability (NanoWS) Research Unit University of South Africa (UNISA Science Campus) Florida (Johannesburg) PO Box 392 South Africa
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32
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Qiu C, Chen W, Schmidt M, Majs F, Douglas TA, Trainor TP. Selective Adsorption of Pb(II) on an Annealed Hematite (1102) Surface: Evidence from Crystal Truncation Rod X-ray Diffraction and Density Functional Theory. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:6651-6660. [PMID: 32396730 DOI: 10.1021/acs.est.0c00060] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The Pb(II)-binding mechanism on an annealed hematite (1102) surface was studied using crystal truncation rod (CTR) X-ray diffraction coupled with density functional theory (DFT) calculations. The best fit CTR model suggested that Pb(II) sorbed selectively to one type of edge-sharing surface site (ES2) over two other potential surface sites. From the best fit model structure, it was found that the Pb surface complex species forms a trigonal pyramid geometry. The base consists of three oxygen groups, two of which are associated with the substrate surface (IO and IIIO) and one that is a distal O extending toward solution. The trigonal pyramid geometry is slightly distorted with Pb-O bond lengths ranging from 2.21 to 2.31 Å and O-Pb-O bond angles ranging from 72° to 75°. Under this structural distortion, the nearest distance between Pb and Fe is found to be 3.39(1) Å. Consistent with the CTR results, DFT calculations indicate the Pb binding energy at the ES2 site is at least 0.16 eV more favorable than that at the other two potential binding sites considered. Using bond-valence rules we propose a stoichiometry of Pb(II) binding on the hematite (1102) surface which indicates proton release through the deprotonation of all oxygen groups bonding to Pb.
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Affiliation(s)
- Canrong Qiu
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, Alaska 99775, United States
| | - Wei Chen
- Department of Physics and School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 01451, United States
| | - Moritz Schmidt
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology, Dresden 01328, Germany
| | - Frantisek Majs
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, Alaska 99775, United States
| | - Thomas A Douglas
- U.S. Army Cold Regions Research and Engineering Laboratory, Fort Wainwright, Alaska 99703, United States
| | - Thomas P Trainor
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, Alaska 99775, United States
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33
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Franceschi G, Schmid M, Diebold U, Riva M. Movable holder for a quartz crystal microbalance for exact growth rates in pulsed laser deposition. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:065003. [PMID: 32611011 DOI: 10.1063/5.0007643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Accepted: 05/29/2020] [Indexed: 06/11/2023]
Abstract
Controlling the amount of material deposited by pulsed laser deposition (PLD) down to fractions of one atomic layer is crucial for nanoscale technologies based on thin-film heterostructures. Albeit unsurpassed for measuring growth rates with high accuracy, the quartz crystal microbalance (QCM) suffers from some limitations when applied to PLD. The strong directionality of the PLD plasma plume and its pronounced dependence on deposition parameters (e.g., background pressure and fluence) require that the QCM is placed at the same position as the substrate during growth. However, QCM sensors are commonly fixed off to one side of the substrate. This also entails fast degradation of the crystal, as it is constantly exposed to the ablated material. The design for a movable QCM holder discussed in this work overcomes these issues. The holder is compatible with standard transfer arms, enabling easy insertion and transfer between a PLD chamber and other adjoining vacuum chambers. The QCM can be placed at the same position as the substrate during PLD growth. Its resonance frequency is measured in vacuum at any location where it can be in contact with an electrical feedthrough, before and after deposition. We tested the design for the deposition of hematite (Fe2O3), comparing the rates derived from the QCM and from reflection high-energy electron diffraction oscillations during homoepitaxial growth.
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Affiliation(s)
- Giada Franceschi
- Institute of Applied Physics, TU Wien, Wiedner Hauptstraße 8-10/E134, 1040 Wien, Austria
| | - Michael Schmid
- Institute of Applied Physics, TU Wien, Wiedner Hauptstraße 8-10/E134, 1040 Wien, Austria
| | - Ulrike Diebold
- Institute of Applied Physics, TU Wien, Wiedner Hauptstraße 8-10/E134, 1040 Wien, Austria
| | - Michele Riva
- Institute of Applied Physics, TU Wien, Wiedner Hauptstraße 8-10/E134, 1040 Wien, Austria
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34
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Leung K, Criscenti LJ, Robinson AC. Quasi-equilibrium predictions of water desorption kinetics from rapidly-heated metal oxide surfaces. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:335101. [PMID: 32241003 DOI: 10.1088/1361-648x/ab85f6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Accepted: 04/02/2020] [Indexed: 06/11/2023]
Abstract
Controlling sub-microsecond desorption of water and other impurities from electrode surfaces at high heating rates is crucial for pulsed power applications. Despite the short time scales involved, quasi-equilibrium ideas based on transition state theory (TST) and Arrhenius temperature dependence have been widely applied to fit desorption activation free energies. In this work, we apply molecular dynamics (MD) simulations in conjunction with equilibrium potential-of-mean-force (PMF) techniques to directly compute the activation free energies (ΔG*) associated with desorption of intact water molecules from Fe2O3and Cr2O3(0001) surfaces. The desorption free energy profiles are diffuse, without maxima, and have substantial dependences on temperature and surface water coverage. Incorporating the predicted ΔG* into an analytical form gives rate equations that are in reasonable agreement with non-equilibrium molecular dynamics desorption simulations. We also show that different ΔG* analytical functional forms which give similar predictions at a particular heating rate can yield desorption times that differ by up to a factor of four or more when the ramp rate is extrapolated by 8 orders of magnitude. This highlights the importance of constructing a physically-motivated ΔG* functional form to predict fast desorption kinetics.
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Affiliation(s)
- Kevin Leung
- Sandia National Laboratories, Albuquerque, NM 87185, United States of America
| | - Louise J Criscenti
- Sandia National Laboratories, Albuquerque, NM 87185, United States of America
| | - Allen C Robinson
- Sandia National Laboratories, Albuquerque, NM 87185, United States of America
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35
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Franceschi G, Kraushofer F, Meier M, Parkinson GS, Schmid M, Diebold U, Riva M. A Model System for Photocatalysis: Ti-Doped α-Fe 2O 3(11̅02) Single-Crystalline Films. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2020; 32:3753-3764. [PMID: 32421058 PMCID: PMC7222102 DOI: 10.1021/acs.chemmater.9b04908] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 04/08/2020] [Indexed: 06/11/2023]
Abstract
Hematite (α-Fe2O3) is one of the most investigated anode materials for photoelectrochemical water splitting. Its efficiency improves by doping with Ti, but the underlying mechanisms are not understood. One hurdle is separating the influence of doping on conductivity, surface states, and morphology, which all affect performance. To address this complexity, one needs well-defined model systems. We build such a model system by growing single-crystalline, atomically flat Ti-doped α-Fe2O3(11̅02) films by pulsed laser deposition (PLD). We characterize their surfaces, combining in situ scanning tunneling microscopy (STM) with density functional theory (DFT), and reveal how dilute Ti impurities modify the atomic-scale structure of the surface as a function of the oxygen chemical potential and Ti content. Ti preferentially substitutes subsurface Fe and causes a local restructuring of the topmost surface layers. Based on the experimental quantification of Ti-induced surface modifications and the structural model we have established, we propose a strategy that can be used to separate the effects of Ti-induced modifications to the surface atomic and electronic structures and bulk conductivity on the reactivity of Ti-doped hematite.
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Affiliation(s)
- Giada Franceschi
- Institute
of Applied Physics, TU Wien, Wiedner Hauptstraβe 8-10/E134, 1040 Wien, Austria
| | - Florian Kraushofer
- Institute
of Applied Physics, TU Wien, Wiedner Hauptstraβe 8-10/E134, 1040 Wien, Austria
| | - Matthias Meier
- Institute
of Applied Physics, TU Wien, Wiedner Hauptstraβe 8-10/E134, 1040 Wien, Austria
- Faculty
of Physics and Center for Computational Materials Science, University of Vienna, Sensengasse 8, 1090 Wien, Austria
| | - Gareth S. Parkinson
- Institute
of Applied Physics, TU Wien, Wiedner Hauptstraβe 8-10/E134, 1040 Wien, Austria
| | - Michael Schmid
- Institute
of Applied Physics, TU Wien, Wiedner Hauptstraβe 8-10/E134, 1040 Wien, Austria
| | - Ulrike Diebold
- Institute
of Applied Physics, TU Wien, Wiedner Hauptstraβe 8-10/E134, 1040 Wien, Austria
| | - Michele Riva
- Institute
of Applied Physics, TU Wien, Wiedner Hauptstraβe 8-10/E134, 1040 Wien, Austria
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36
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Guan Y, Ji P, Wan J, Zhang D, Wang Z, Tian H, Hu C, Hu B, Tang Q, Xi Y. Ag-modified Fe 2O 3 nanoparticles on a carbon cloth as an anode material for high-performance supercapacitors. NANOTECHNOLOGY 2020; 31:125405. [PMID: 31751972 DOI: 10.1088/1361-6528/ab5a29] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
By exploiting the storage performance of supercapacitors, iron has the potential to be used as a new anode material. However, this potential is limited by unsatisfactory electrical conductivity and poor cycling stability which impact the energy and power density. Consequently a foundation for improving the electrical conductivity and cycling stability of iron materials to obtain good storage performance is needed. In this work, Ag-modified Fe2O3 nanoparticles on carbon cloth were synthesized as an anode material for supercapacitors. The specific capacitance of the composite material reaches 10.39 F cm-2 (2734.2 F g-1) at a current density of 1 mA cm-2 and remains at 83% of this value after 12 000 cycles. The energy density is 379.8 Wh kg-1 at a power density of 131.6 W kg-1 and remains at 123.9 Wh kg-1 at a power density of 2631.6 W kg-1. The electrical conductivity and interfacial effect created between Ag@Fe2O3 is confirmed with density functional theory calculations. The packaged asymmetric supercapacitor devices have flexibility and can light ten LEDs for 2 min 30 s, with an energy density of 60.3 Wh kg-1 that can be reached at a power density of 1063.8 W kg-1 and remain at 16 Wh kg-1 even at a power density of 4255.3 W kg-1.
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Affiliation(s)
- Yuzhu Guan
- Department of Applied Physics, State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, Chongqing, 400044, People's Republic of China
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37
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Abstract
In heterogeneous catalysis, surfaces decorated with uniformly dispersed, catalytically-active (nano)particles are a key requirement for excellent performance. Beside standard catalyst preparation routines—with limitations in controlling catalyst surface structure (i.e., particle size distribution or dispersion)—we present here a novel time efficient route to precisely tailor catalyst surface morphology and composition of perovskites. Perovskite-type oxides of nominal composition ABO3 with transition metal cations on the B-site can exsolve the B-site transition metal upon controlled reduction. In this exsolution process, the transition metal emerges from the oxide lattice and migrates to the surface where it forms catalytically active nanoparticles. Doping the B-site with reducible and catalytically highly active elements, offers the opportunity of tailoring properties of exsolution catalysts. Here, we present the synthesis of two novel perovskite catalysts Nd0.6Ca0.4FeO3-δ and Nd0.6Ca0.4Fe0.9Co0.1O3-δ with characterisation by (in situ) XRD, SEM/TEM and XPS, supported by theory (DFT+U). Fe nanoparticle formation was observed for Nd0.6Ca0.4FeO3-δ. In comparison, B site cobalt doping leads, already at lower reduction temperatures, to formation of finely dispersed Co nanoparticles on the surface. These novel perovskite-type catalysts are highly promising for applications in chemical energy conversion. First measurements revealed that exsolved Co nanoparticles significantly improve the catalytic activity for CO2 activation via reverse water gas shift reaction.
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38
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Ethanol Conversion to Short-Chain Olefins Over ZSM-5 Zeolite Catalysts Enhanced with P, Fe, and Ni. Top Catal 2020. [DOI: 10.1007/s11244-020-01229-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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39
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Mallesham B, Roy S, Bose S, Nair AN, Sreenivasan S, Shutthanandan V, Ramana CV. Crystal Chemistry, Band-Gap Red Shift, and Electrocatalytic Activity of Iron-Doped Gallium Oxide Ceramics. ACS OMEGA 2020; 5:104-112. [PMID: 31956757 PMCID: PMC6963903 DOI: 10.1021/acsomega.9b01604] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 09/10/2019] [Indexed: 06/10/2023]
Abstract
This work for the first time unfurls the fundamental mechanisms and sets the stage for an approach to derive electrocatalytic activity, which is otherwise not possible, in a traditionally known wide band-gap oxide material. Specifically, we report on the tunable optical properties, in terms of wide spectral selectivity and red-shifted band gap, and electrocatalytic behavior of iron (Fe)-doped gallium oxide (β-Ga2O3) model system. X-ray diffraction (XRD) studies of sintered Ga2-x Fe x O3 (GFO) (0.0 ≤ x ≤ 0.3) compounds provide evidence for the Fe3+ substitution at Ga3+ site without any secondary phase formation. Rietveld refinement of XRD patterns reveals that the GFO compounds crystallize in monoclinic crystal symmetry with a C2/m space group. The electronic structure of the GFO compounds probed using X-ray photoelectron spectroscopy data reveals that at lower concentrations, Fe exhibits mixed chemical valence states (Fe3+, Fe2+), whereas single chemical valence state (Fe3+) is evident for higher Fe content (x = 0.20-0.30). The optical absorption spectra reveal a significant red shift in the optical band gap with Fe doping. The origin of the significant red shift even at low concentrations of Fe (x = 0.05) is attributed to the strong sp-d exchange interaction originated from the 3d5 electrons of Fe3+. The optical absorption edge observed at ≈450 nm with lower intensity is the characteristic of Fe-doped compounds associated with Fe3+-Fe3+ double-excitation process. Coupled with an optical band-gap red shift, electrocatalytic studies of GFO compounds reveal that, interestingly, Fe-doped Ga2O3 compound exhibits electrocatalytic activity in contrast to intrinsic Ga2O3. Fe-doped samples (GFO) demonstrated appreciable electrocatalytic activity toward the generation of H2 through electrocatalytic water splitting. An onset potential and Tafel slope of GFO compounds include ∼900 mV, ∼210 mV dec-1 (x = 0.15) and ∼1036 mV, ∼290 mV dec-1 (x = 0.30), respectively. The electrocatalytic activity of Fe-doped Ga-oxide compounds is attributed to the cumulative effect of different mechanisms such as doping resulting in new catalytic centers, enhanced conductivity, and electron mobility. Hence, in this report, for the first time, we explored a new pathway; the electrocatalytic behavior of Fe-doped Ga2O3 resulted due to Fe chemical states and red shift in the optical band gap. The implications derived from this work may be applicable to a large class of compounds, and further options may be available to design functional materials for electrocatalytic energy production.
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Affiliation(s)
- Bandi Mallesham
- Center
for Advanced Materials Research (CMR), Department of Metallurgical, Materials
and Biomedical Engineering and Department of Chemistry and Biochemistry, University of Texas at El Paso, 500 W University Ave, El Paso, Texas 79968, United States
| | - Swadipta Roy
- Center
for Advanced Materials Research (CMR), Department of Metallurgical, Materials
and Biomedical Engineering and Department of Chemistry and Biochemistry, University of Texas at El Paso, 500 W University Ave, El Paso, Texas 79968, United States
- Environmental
Molecular Sciences Laboratory (EMSL), Pacific
Northwest National Laboratory (PNNL), Richland, Washington 99352, United States
| | - Saptasree Bose
- Center
for Advanced Materials Research (CMR), Department of Metallurgical, Materials
and Biomedical Engineering and Department of Chemistry and Biochemistry, University of Texas at El Paso, 500 W University Ave, El Paso, Texas 79968, United States
| | - Aruna N. Nair
- Center
for Advanced Materials Research (CMR), Department of Metallurgical, Materials
and Biomedical Engineering and Department of Chemistry and Biochemistry, University of Texas at El Paso, 500 W University Ave, El Paso, Texas 79968, United States
| | - Sreeprasad Sreenivasan
- Center
for Advanced Materials Research (CMR), Department of Metallurgical, Materials
and Biomedical Engineering and Department of Chemistry and Biochemistry, University of Texas at El Paso, 500 W University Ave, El Paso, Texas 79968, United States
| | - Vaithiyalingam Shutthanandan
- Environmental
Molecular Sciences Laboratory (EMSL), Pacific
Northwest National Laboratory (PNNL), Richland, Washington 99352, United States
| | - Chintalapalle V. Ramana
- Center
for Advanced Materials Research (CMR), Department of Metallurgical, Materials
and Biomedical Engineering and Department of Chemistry and Biochemistry, University of Texas at El Paso, 500 W University Ave, El Paso, Texas 79968, United States
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40
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Ross A, Lebrun R, Gomonay O, Grave DA, Kay A, Baldrati L, Becker S, Qaiumzadeh A, Ulloa C, Jakob G, Kronast F, Sinova J, Duine R, Brataas A, Rothschild A, Kläui M. Propagation Length of Antiferromagnetic Magnons Governed by Domain Configurations. NANO LETTERS 2020; 20:306-313. [PMID: 31809058 DOI: 10.1021/acs.nanolett.9b03837] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The compensated magnetic order and characteristic terahertz frequencies of antiferromagnetic materials make them promising candidates to develop a new class of robust, ultrafast spintronic devices. The manipulation of antiferromagnetic spin-waves in thin films is anticipated to lead to new exotic phenomena such as spin-superfluidity, requiring an efficient propagation of spin-waves in thin films. However, the reported decay length in thin films has so far been limited to a few nanometers. In this work, we achieve efficient spin-wave propagation over micrometer distances in thin films of the insulating antiferromagnet hematite with large magnetic domains while evidencing much shorter attenuation lengths in multidomain thin films. Through transport and magnetic imaging, we determine the role of the magnetic domain structure and spin-wave scattering at domain walls to govern the transport. We manipulate the spin transport by tailoring the domain configuration through field cycle training. For the appropriate crystalline orientation, zero-field spin transport is achieved across micrometers, as required for device integration.
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Affiliation(s)
- Andrew Ross
- Institut für Physik , Johannes Gutenberg Universität-Mainz , 55099 , Mainz , Germany
- Graduate School of Excellence Materials Science in Mainz (MAINZ) , Staudinger Weg 9 , 55128 , Mainz , Germany
| | - Romain Lebrun
- Institut für Physik , Johannes Gutenberg Universität-Mainz , 55099 , Mainz , Germany
| | - Olena Gomonay
- Institut für Physik , Johannes Gutenberg Universität-Mainz , 55099 , Mainz , Germany
| | - Daniel A Grave
- Department of Materials Science and Engineering , Technion-Israel Institute of Technology , Haifa 32000 , Israel
| | - Asaf Kay
- Department of Materials Science and Engineering , Technion-Israel Institute of Technology , Haifa 32000 , Israel
| | - Lorenzo Baldrati
- Institut für Physik , Johannes Gutenberg Universität-Mainz , 55099 , Mainz , Germany
| | - Sven Becker
- Institut für Physik , Johannes Gutenberg Universität-Mainz , 55099 , Mainz , Germany
| | - Alireza Qaiumzadeh
- Center for Quantum Spintronics, Department of Physics , Norwegian University of Science and Technology , NO-7491 Trondheim , Norway
| | - Camilo Ulloa
- Institute for Theoretical Physics , Utrecht University , Princetonplein 5 , 3584 CC Utrecht , The Netherlands
| | - Gerhard Jakob
- Institut für Physik , Johannes Gutenberg Universität-Mainz , 55099 , Mainz , Germany
- Graduate School of Excellence Materials Science in Mainz (MAINZ) , Staudinger Weg 9 , 55128 , Mainz , Germany
| | - Florian Kronast
- Helmholtz-Zentrum Berlin für Materialien und Energie , Albert-Einstein-Strasse 15 , D-12489 Berlin , Germany
| | - Jairo Sinova
- Institut für Physik , Johannes Gutenberg Universität-Mainz , 55099 , Mainz , Germany
- Institute of Physics ASCR , Cukrovarnicka 10 , 162 53 Praha 6 , Czech Republic
| | - Rembert Duine
- Center for Quantum Spintronics, Department of Physics , Norwegian University of Science and Technology , NO-7491 Trondheim , Norway
- Institute for Theoretical Physics , Utrecht University , Princetonplein 5 , 3584 CC Utrecht , The Netherlands
- Department of Applied Physics , Eindhoven University of Technology , P.O. Box 513, 5600 MB Eindhoven , The Netherlands
| | - Arne Brataas
- Center for Quantum Spintronics, Department of Physics , Norwegian University of Science and Technology , NO-7491 Trondheim , Norway
| | - Avner Rothschild
- Department of Materials Science and Engineering , Technion-Israel Institute of Technology , Haifa 32000 , Israel
| | - Mathias Kläui
- Institut für Physik , Johannes Gutenberg Universität-Mainz , 55099 , Mainz , Germany
- Graduate School of Excellence Materials Science in Mainz (MAINZ) , Staudinger Weg 9 , 55128 , Mainz , Germany
- Center for Quantum Spintronics, Department of Physics , Norwegian University of Science and Technology , NO-7491 Trondheim , Norway
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41
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Comparative Study on Surface Structure, Electronic Properties of Sulfide and Oxide Minerals: A First-Principles Perspective. MINERALS 2019. [DOI: 10.3390/min9060329] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
First-principle calculations were used to investigate the surface structure and electronic properties of sulfide (pyrite, galena, and sphalerite) and oxide minerals (hematite, cerussite, and smithsonite). Surface relaxation and Femi energy, as well as projected DOS, are considered. Results show that the surface atoms of the sulfide minerals are more susceptible and more easily affected by the fracture bonds. The sulfide surfaces possess higher chemical potential than the corresponding oxide surfaces, and are more likely to be electron donors in reactions. The S 3p states are the mainly contributing states in the sulfide surface, while that in the oxide surface are O 2p states. The bonds of the sulfide surface have more covalent features and that of the oxide surface are ionic interactions. The O–M (M represents Fe, Pb or Zn) bonds are more stable, as the DOS of the oxide surfaces distribute in the lower energy range.
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42
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Divya NG, Junaid Bushiri M. High index facet bounded α-Fe2O3 pseudocubic nanocrystals with enhanced electrochemical properties: Zn2+ ion assisted solvo-hydrothermal synthesis. CrystEngComm 2019. [DOI: 10.1039/c8ce01837e] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Pseudocubic α-Fe2O3 nanocrystals were grown by a surfactant-free, low temperature, solvo-hydrothermal process and characterised by XRD, FESEM, TEM, FTIR, Raman, XPS and UV-vis analysis.
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Affiliation(s)
- Neravathu G. Divya
- Department of Physics
- Cochin University of Science and Technology
- Kochi
- India
| | - M. Junaid Bushiri
- Department of Physics
- Cochin University of Science and Technology
- Kochi
- India
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43
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Lane JMD, Leung K, Thompson AP, Cuneo ME. Water desorption from rapidly-heated metal oxide surfaces-first principles, molecular dynamics, and the Temkin isotherm. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:465002. [PMID: 30259877 DOI: 10.1088/1361-648x/aae4af] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Quantitative understanding and control of water and impurity desorption from steel surfaces are crucial for high-voltage, pulsed power, vacuum technology, catalysis, and environmental applications. We apply a suite of modeling techniques, ranging from electronic density functional theory, to classical molecular dynamics (MD) and grand canonical Monte Carlo (GCMC) methods to study the thermodynamics and kinetics of fast water desorption from different surfaces of hematite Fe2O3 and Cr2O3. Water binding energies on chromium oxide are found to be higher than iron oxide at zero temperature. MD simulations are conducted on Fe2O3 surfaces using thermodynamically consistent initial water inventory deduced with GCMC. The resulting time- and temperature-dependent desorption profiles on the Fe2O3 [Formula: see text] surfaces show multi-water cooperative behavior which cannot be deduced from zero temperature predictions, but which are in reasonable agreement with simple Temkin isotherm model estimates if finite temperature effects are incorporated into the Temkin binding energy parameter. Qualitatively different desorption behaviors associated with the [Formula: see text] and [Formula: see text] facets are discussed.
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Affiliation(s)
- J Matthew D Lane
- Sandia National Laboratories, Albuquerque, NM 87185, United States of America
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