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Di Liberto G, Pacchioni G. Modeling Single-Atom Catalysis. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2307150. [PMID: 37749881 DOI: 10.1002/adma.202307150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 08/17/2023] [Indexed: 09/27/2023]
Abstract
Electronic structure calculations represent an essential complement of experiments to characterize single-atom catalysts (SACs), consisting of isolated metal atoms stabilized on a support, but also to predict new catalysts. However, simulating SACs with quantum chemistry approaches is not as simple as often assumed. In this work, the essential factors that characterize a reliable simulation of SACs activity are examined. The Perspective focuses on the importance of precise atomistic characterization of the active site, since even small changes in the metal atom's surroundings can result in large changes in reactivity. The dynamical behavior and stability of SACs under working conditions, as well as the importance of adopting appropriate methods to solve the Schrödinger equation for a quantitative evaluation of reaction energies are addressed. The Perspective also focuses on the relevance of the model adopted. For electrocatalysis this must include the effects of the solvent, the presence of electrolytes, the pH, and the external potential. Finally, it is discussed how the similarities between SACs and coordination compounds may result in reaction intermediates that usually are not observed on metal electrodes. When these aspects are not adequately considered, the predictive power of electronic structure calculations is quite limited.
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Affiliation(s)
- Giovanni Di Liberto
- Dipartimento di Scienza dei Materiali, Università degli studi di Milano Bicocca, Via R. Cozzi 55, Milano, 20125, Italy
| | - Gianfranco Pacchioni
- Dipartimento di Scienza dei Materiali, Università degli studi di Milano Bicocca, Via R. Cozzi 55, Milano, 20125, Italy
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2
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Chen L, Allec SI, Nguyen MT, Kovarik L, Hoffman AS, Hong J, Meira D, Shi H, Bare SR, Glezakou VA, Rousseau R, Szanyi J. Dynamic Evolution of Palladium Single Atoms on Anatase Titania Support Determines the Reverse Water-Gas Shift Activity. J Am Chem Soc 2023; 145:10847-10860. [PMID: 37145876 DOI: 10.1021/jacs.3c02326] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Research interest in single-atom catalysts (SACs) has been continuously increasing. However, the lack of understanding of the dynamic behaviors of SACs during applications hinders catalyst development and mechanistic understanding. Herein, we report on the evolution of active sites over Pd/TiO2-anatase SAC (Pd1/TiO2) in the reverse water-gas shift (rWGS) reaction. Combining kinetics, in situ characterization, and theory, we show that at T ≥ 350 °C, the reduction of TiO2 by H2 alters the coordination environment of Pd, creating Pd sites with partially cleaved Pd-O interfacial bonds and a unique electronic structure that exhibit high intrinsic rWGS activity through the carboxyl pathway. The activation by H2 is accompanied by the partial sintering of single Pd atoms (Pd1) into disordered, flat, ∼1 nm diameter clusters (Pdn). The highly active Pd sites in the new coordination environment under H2 are eliminated by oxidation, which, when performed at a high temperature, also redisperses Pdn and facilitates the reduction of TiO2. In contrast, Pd1 sinters into crystalline, ∼5 nm particles (PdNP) during CO treatment, deactivating Pd1/TiO2. During the rWGS reaction, the two Pd evolution pathways coexist. The activation by H2 dominates, leading to the increasing rate with time-on-stream, and steady-state Pd active sites similar to the ones formed under H2. This work demonstrates how the coordination environment and nuclearity of metal sites on a SAC evolve during catalysis and pretreatments and how their activity is modulated by these behaviors. These insights on SAC dynamics and the structure-function relationship are valuable to mechanistic understanding and catalyst design.
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Affiliation(s)
- Linxiao Chen
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Sarah I Allec
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Manh-Thuong Nguyen
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Libor Kovarik
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Adam S Hoffman
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Jiyun Hong
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Debora Meira
- Canadian Light Source Inc., 44 Innovation Boulevard, Saskatoon, Saskatchewan S7N 2V3, Canada
| | - Honghong Shi
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Simon R Bare
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | | | - Roger Rousseau
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - János Szanyi
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
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3
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Puntscher L, Daninger K, Schmid M, Diebold U, Parkinson GS. A study of Pt, Rh, Ni and Ir dispersion on anatase TiO2(101) and the role of water. Electrochim Acta 2023. [DOI: 10.1016/j.electacta.2023.142190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
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4
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Marino S, Wei L, Cortes-Reyes M, Cheng Y, Laing P, Cavataio G, Paolucci C, Epling W. Rhodium Catalyst Structural Changes during, and Their Impacts on the Kinetics of, CO Oxidation. JACS AU 2023; 3:459-467. [PMID: 36873703 PMCID: PMC9976345 DOI: 10.1021/jacsau.2c00595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 01/18/2023] [Accepted: 01/20/2023] [Indexed: 06/18/2023]
Abstract
Catalysts can undergo structural changes during the reaction, affecting the number and/or the shape of active sites. For example, Rh can undergo interconversion between nanoparticles and single atoms when CO is present in the reaction mixture. Therefore, calculating a turnover frequency in such cases can be challenging as the number of active sites can change depending on the reaction conditions. Here, we use CO oxidation kinetics to track Rh structural changes occurring during the reaction. The apparent activation energy, considering the nanoparticles as the active sites, was constant in different temperature regimes. However, in a stoichiometric excess of O2, there were observed changes in the pre-exponential factor, which we link to changes in the number of active Rh sites. An excess of O2 enhanced CO-induced Rh nanoparticle disintegration into single atoms, affecting catalyst activity. The temperature at which these structural changes occur depend on Rh particle size, with small particle sizes disintegrating at higher temperature, relative to the temperature required to break apart bigger particles. Rh structural changes were also observed during in situ infrared spectroscopic studies. Combining CO oxidation kinetics and spectroscopic studies allowed us to calculate the turnover frequency before and after nanoparticle redispersion into single atoms.
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Affiliation(s)
- Silvia Marino
- Department
of Chemical Engineering, University of Virginia, Charlottesville, Virginia 22903, United States
| | - Lai Wei
- Department
of Chemical Engineering, University of Virginia, Charlottesville, Virginia 22903, United States
| | - Marina Cortes-Reyes
- Department
of Chemical Engineering, University of Virginia, Charlottesville, Virginia 22903, United States
| | - Yisun Cheng
- Research
and Advanced Engineering, Ford Motor Company, Dearborn, Michigan 48124, United States
| | - Paul Laing
- Research
and Advanced Engineering, Ford Motor Company, Dearborn, Michigan 48124, United States
| | - Giovanni Cavataio
- Research
and Advanced Engineering, Ford Motor Company, Dearborn, Michigan 48124, United States
| | - Christopher Paolucci
- Department
of Chemical Engineering, University of Virginia, Charlottesville, Virginia 22903, United States
| | - William Epling
- Department
of Chemical Engineering, University of Virginia, Charlottesville, Virginia 22903, United States
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5
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Wu D, Liu S, Zhong M, Zhao J, Du C, Yang Y, Sun Y, Lin J, Wan S, Wang S, Huang J, Yao Y, Li Z, Xiong H. Nature and Dynamic Evolution of Rh Single Atoms Trapped by CeO 2 in CO Hydrogenation. ACS Catal 2022. [DOI: 10.1021/acscatal.2c02103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Danfeng Wu
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, 422 South Siming Road, Xiamen 361005, China
- Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), 4221 Xiangan South Road, Xiamen 361102, China
| | - Sixu Liu
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, 422 South Siming Road, Xiamen 361005, China
- Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), 4221 Xiangan South Road, Xiamen 361102, China
| | - Mingqi Zhong
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, 422 South Siming Road, Xiamen 361005, China
| | - Jiafei Zhao
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, 422 South Siming Road, Xiamen 361005, China
| | - Congcong Du
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, 422 South Siming Road, Xiamen 361005, China
| | - Yanling Yang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Energy, Xiamen University, Xiamen 361102, China
| | - Yifei Sun
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Energy, Xiamen University, Xiamen 361102, China
| | - Jingdong Lin
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, 422 South Siming Road, Xiamen 361005, China
| | - Shaolong Wan
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, 422 South Siming Road, Xiamen 361005, China
| | - Shuai Wang
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, 422 South Siming Road, Xiamen 361005, China
| | - Jianyu Huang
- Clean Nano Energy Center, State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China
| | - Yali Yao
- Institute for the Development of Energy for African Sustainability, University of South Africa, Private Bag X6, Roodepoort 1710, South Africa
| | - Zhe Li
- Key Laboratory of Catalysis and Energy Materials Chemistry of Ministry of Education and Hubei Key Laboratory of Catalysis and Materials Science, South-Central Minzu University, Wuhan 430074, China
| | - Haifeng Xiong
- State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, 422 South Siming Road, Xiamen 361005, China
- Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), 4221 Xiangan South Road, Xiamen 361102, China
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6
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Hoffman AJ, Asokan C, Gadinas N, Schroeder E, Zakem G, Nystrom SV, Getsoian A“B, Christopher P, Hibbitts D. Experimental and Theoretical Characterization of Rh Single Atoms Supported on γ-Al 2O 3 with Varying Hydroxyl Contents during NO Reduction by CO. ACS Catal 2022. [DOI: 10.1021/acscatal.2c02813] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Alexander J. Hoffman
- Department of Chemical Engineering, University of Florida, Gainesville, Florida 32611, United States
| | - Chithra Asokan
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Nicholas Gadinas
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Emily Schroeder
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Gregory Zakem
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - Steven V. Nystrom
- Department of Chemical Engineering, University of Florida, Gainesville, Florida 32611, United States
| | - Andrew “Bean” Getsoian
- Research and Advanced Engineering, Ford Motor Company, Dearborn, Michigan 48124, United States
| | - Phillip Christopher
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, California 93106, United States
| | - David Hibbitts
- Department of Chemical Engineering, University of Florida, Gainesville, Florida 32611, United States
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7
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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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8
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Dong C, Gao Z, Li Y, Peng M, Wang M, Xu Y, Li C, Xu M, Deng Y, Qin X, Huang F, Wei X, Wang YG, Liu H, Zhou W, Ma D. Fully exposed palladium cluster catalysts enable hydrogen production from nitrogen heterocycles. Nat Catal 2022. [DOI: 10.1038/s41929-022-00769-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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9
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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: 4.0] [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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10
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Thang HV, Maleki F, Tosoni S, Pacchioni G. Vibrational Properties of CO Adsorbed on Au Single Atom Catalysts on TiO2(101), ZrO2(101), CeO2(111), and LaFeO3(001) Surfaces: A DFT Study. Top Catal 2021. [DOI: 10.1007/s11244-021-01514-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
AbstractThe nature and local environment of Au single atoms supported and stabilized on four different oxides is studied by means of DFT + U calculations using CO as probe molecule and its stretching frequency, ωe, as a fingerprint of the site where the Au atom is bound. Four oxides are considered, anatase TiO2, tetragonal ZrO2, cubic CeO2, and a perovskite LaFeO3. In this latter case a recently reported experimental study has detected a stretching mode for CO adsorbed on Au1/LaFeO3 of 2215 cm−1, with a large blue shift, ∆ω(CO) = 72 cm−1 with respect to free CO. In order to identify the Au adsorption site that can give rise to this large blue-shift we have considered five cases: (a) Au replacing a lattice cation, (Au)subM; (b) Au replacing a lattice O anion, (Au)subO; (c) Au adsorbed on the surface, (Au)ads; (d) Au bound to an extra O atom on the surface, (AuO)ads, or (e) Au bound to two extra O atoms on the surface, (AuO2)ads. It turns out that the correct reproduction of ∆ω for CO adsorbed on positively charged gold, Auδ+, is challenging for DFT. Therefore, we have performed a comparative study of Auδ+-CO molecular compounds for which ωe(CO) is known experimentally using various kinds of DFT functionals and accurate CCSD and CCSD(T) quantum chemistry methods. Also based on this comparison we propose a tentative assignment for the observed frequency of CO adsorbed on Au1/LaFeO3 single atom catalyst.
Graphic Abstract
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11
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Zakem G, Ro I, Finzel J, Christopher P. Support functionalization as an approach for modifying activation entropies of catalytic reactions on atomically dispersed metal sites. J Catal 2021. [DOI: 10.1016/j.jcat.2021.07.030] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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12
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Doherty F, Goldsmith BR. Rhodium Single‐Atom Catalysts on Titania for Reverse Water Gas Shift Reaction Explored by First Principles Mechanistic Analysis and Compared to Nanoclusters. ChemCatChem 2021. [DOI: 10.1002/cctc.202100292] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Francis Doherty
- Department of Chemical Engineering University of Michigan 2300 Hayward St. Ann Arbor MI 48109-2136 USA
- Catalysis Science and Technology Institute University of Michigan 2300 Hayward St. Ann Arbor MI 48109-2136 USA
| | - Bryan R. Goldsmith
- Department of Chemical Engineering University of Michigan 2300 Hayward St. Ann Arbor MI 48109-2136 USA
- Catalysis Science and Technology Institute University of Michigan 2300 Hayward St. Ann Arbor MI 48109-2136 USA
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13
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Tieu P, Yan X, Xu M, Christopher P, Pan X. Directly Probing the Local Coordination, Charge State, and Stability of Single Atom Catalysts by Advanced Electron Microscopy: A Review. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2006482. [PMID: 33624398 DOI: 10.1002/smll.202006482] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 12/18/2020] [Indexed: 06/12/2023]
Abstract
The drive for atom efficient catalysts with carefully controlled properties has motivated the development of single atom catalysts (SACs), aided by a variety of synthetic methods, characterization techniques, and computational modeling. The distinct capabilities of SACs for oxidation, hydrogenation, and electrocatalytic reactions have led to the optimization of activity and selectivity through composition variation. However, characterization methods such as infrared and X-ray spectroscopy are incapable of direct observations at atomic scale. Advances in transmission electron microscopy (TEM) including aberration correction, monochromators, environmental TEM, and micro-electro-mechanical system based in situ holders have improved catalysis study, allowing researchers to peer into regimes previously unavailable, observing critical structural and chemical information at atomic scale. This review presents recent development and applications of TEM techniques to garner information about the location, bonding characteristics, homogeneity, and stability of SACs. Aberration corrected TEM imaging routinely achieves sub-Ångstrom resolution to reveal the atomic structure of materials. TEM spectroscopy provides complementary information about local composition, chemical bonding, electronic properties, and atomic/molecular vibration with superior spatial resolution. In situ/operando TEM directly observe the evolution of SACs under reaction conditions. This review concludes with remarks on the challenges and opportunities for further development of TEM to study SACs.
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Affiliation(s)
- Peter Tieu
- Department of Chemistry, University of California, Irvine, CA, 92697, USA
| | - Xingxu Yan
- Department of Materials Science and Engineering, University of California, Irvine, CA, 92697, USA
| | - Mingjie Xu
- Department of Materials Science and Engineering, University of California, Irvine, CA, 92697, USA
- Irvine Materials Research Institute (IMRI), University of California, Irvine, CA, 92697, USA
| | - Phillip Christopher
- Department of Chemical Engineering, University of California, Santa Barbara, CA, 93106, USA
| | - Xiaoqing Pan
- Department of Materials Science and Engineering, University of California, Irvine, CA, 92697, USA
- Irvine Materials Research Institute (IMRI), University of California, Irvine, CA, 92697, USA
- Department of Physics and Astronomy, University of California, Irvine, CA, 92697, USA
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14
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Zhang X, Yan P, Zhao B, Zhang ZC. Identification of electron-rich mononuclear Ni atoms on TiO 2-A distinguished from Ni particles on TiO 2-R in guaiacol hydrodeoxygenation pathways. Catal Sci Technol 2021. [DOI: 10.1039/d0cy01720e] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electron-rich mononuclear Ni atoms located at the oxygen vacancies on TiO2-A are the active sites for selective hydrodeoxygenation of guaiacol to phenolics, while the reduced Ni particles on TiO2-R catalyze hydrogenative aromatic ring saturation.
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Affiliation(s)
- Xiaoqiang Zhang
- State Key Laboratory of Catalysis
- Dalian National Laboratory for Clean Energy
- Dalian Institute of Chemical Physics, Chinese Academy of Sciences
- Dalian 116023
- P. R. China
| | - Peifang Yan
- State Key Laboratory of Catalysis
- Dalian National Laboratory for Clean Energy
- Dalian Institute of Chemical Physics, Chinese Academy of Sciences
- Dalian 116023
- P. R. China
| | - Bin Zhao
- State Key Laboratory of Fine Chemicals
- PSU-DUT Joint Center for Energy Research
- School of Chemical Engineering
- Dalian University of Technology
- Dalian 116024
| | - Z. Conrad Zhang
- State Key Laboratory of Catalysis
- Dalian National Laboratory for Clean Energy
- Dalian Institute of Chemical Physics, Chinese Academy of Sciences
- Dalian 116023
- P. R. China
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15
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Resasco J, Christopher P. Atomically Dispersed Pt-group Catalysts: Reactivity, Uniformity, Structural Evolution, and Paths to Increased Functionality. J Phys Chem Lett 2020; 11:10114-10123. [PMID: 33191757 DOI: 10.1021/acs.jpclett.0c02904] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The development of experimental and computational tools that give accurate and visual active site descriptions has renewed research interest in atomically dispersed metal catalysts. In this perspective, we describe our approach to synthesizing and understanding atomically dispersed Pt-group metals on oxide supports. Using site-specific characterization, we show that these metal species have distinct reactivity from metal clusters. We argue that producing materials where all metal sites have identical local coordination is key to both accurately assessing catalytic properties and achieving single-site behavior. Methods for assessing site uniformity are considered. We show that producing uniform metal species allows us to describe their structure at the atomic scale and understand how this structure evolves under different conditions. Finally, we suggest pathways to increased functionality for atomically dispersed catalysts, through control of their local coordination and steric environment and through cooperativity with different sites.
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Affiliation(s)
- Joaquin Resasco
- Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, California 93117, United States
| | - Phillip Christopher
- Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, California 93117, United States
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16
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Kaiser SK, Chen Z, Faust Akl D, Mitchell S, Pérez-Ramírez J. Single-Atom Catalysts across the Periodic Table. Chem Rev 2020; 120:11703-11809. [PMID: 33085890 DOI: 10.1021/acs.chemrev.0c00576] [Citation(s) in RCA: 329] [Impact Index Per Article: 82.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Isolated atoms featuring unique reactivity are at the heart of enzymatic and homogeneous catalysts. In contrast, although the concept has long existed, single-atom heterogeneous catalysts (SACs) have only recently gained prominence. Host materials have similar functions to ligands in homogeneous catalysts, determining the stability, local environment, and electronic properties of isolated atoms and thus providing a platform for tailoring heterogeneous catalysts for targeted applications. Within just a decade, we have witnessed many examples of SACs both disrupting diverse fields of heterogeneous catalysis with their distinctive reactivity and substantially enriching our understanding of molecular processes on surfaces. To date, the term SAC mostly refers to late transition metal-based systems, but numerous examples exist in which isolated atoms of other elements play key catalytic roles. This review provides a compositional encyclopedia of SACs, celebrating the 10th anniversary of the introduction of this term. By defining single-atom catalysis in the broadest sense, we explore the full elemental diversity, joining different areas across the whole periodic table, and discussing historical milestones and recent developments. In particular, we examine the coordination structures and associated properties accessed through distinct single-atom-host combinations and relate them to their main applications in thermo-, electro-, and photocatalysis, revealing trends in element-specific evolution, host design, and uses. Finally, we highlight frontiers in the field, including multimetallic SACs, atom proximity control, and possible applications for multistep and cascade reactions, identifying challenges, and propose directions for future development in this flourishing field.
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Affiliation(s)
- Selina K Kaiser
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 1, 8093 Zurich, Switzerland
| | - Zupeng Chen
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 1, 8093 Zurich, Switzerland
| | - Dario Faust Akl
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 1, 8093 Zurich, Switzerland
| | - Sharon Mitchell
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 1, 8093 Zurich, Switzerland
| | - Javier Pérez-Ramírez
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 1, 8093 Zurich, Switzerland
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17
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Asokan C, Yang Y, Dang A, Getsoian A“B, Christopher P. Low-Temperature Ammonia Production during NO Reduction by CO Is Due to Atomically Dispersed Rhodium Active Sites. ACS Catal 2020. [DOI: 10.1021/acscatal.0c01249] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Chithra Asokan
- Department of Chemical Engineering, University of California, Santa Barbara, 93117 United States,
| | - Yang Yang
- Department of Chemical Engineering, University of California, Santa Barbara, 93117 United States,
| | - Alan Dang
- Department of Chemical Engineering, University of California, Santa Barbara, 93117 United States,
| | | | - Phillip Christopher
- Department of Chemical Engineering, University of California, Santa Barbara, 93117 United States,
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