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Kobayashi T, Ikeda T, Nakayama A. Long-range proton and hydroxide ion transfer dynamics at the water/CeO 2 interface in the nanosecond regime: reactive molecular dynamics simulations and kinetic analysis. Chem Sci 2024; 15:6816-6832. [PMID: 38725504 PMCID: PMC11077578 DOI: 10.1039/d4sc01422g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Accepted: 04/02/2024] [Indexed: 05/12/2024] Open
Abstract
The structural properties, dynamical behaviors, and ion transport phenomena at the interface between water and cerium oxide are investigated by reactive molecular dynamics (MD) simulations employing neural network potentials (NNPs). The NNPs are trained to reproduce density functional theory (DFT) results, and DFT-based MD (DFT-MD) simulations with enhanced sampling techniques and refinement schemes are employed to efficiently and systematically acquire training data that include diverse hydrogen-bonding configurations caused by proton hopping events. The water interfaces with two low-index surfaces of (111) and (110) are explored with these NNPs, and the structure and long-range proton and hydroxide ion transfer dynamics are examined with unprecedented system sizes and long simulation times. Various types of proton hopping events at the interface are categorized and analyzed in detail. Furthermore, in order to decipher the proton and hydroxide ion transport phenomena along the surface, a counting analysis based on the semi-Markov process is formulated and applied to the MD trajectories to obtain reaction rates by considering the transport as stochastic jump processes. Through this model, the coupling between hopping events, vibrational motions, and hydrogen bond networks at the interface are quantitatively examined, and the high activity and ion transport phenomena at the water/CeO2 interface are unequivocally revealed in the nanosecond regime.
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Affiliation(s)
- Taro Kobayashi
- Department of Chemical System Engineering, The University of Tokyo Tokyo 113-8656 Japan
| | - Tatsushi Ikeda
- Department of Chemical System Engineering, The University of Tokyo Tokyo 113-8656 Japan
| | - Akira Nakayama
- Department of Chemical System Engineering, The University of Tokyo Tokyo 113-8656 Japan
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Röckert A, Kullgren J, Hermansson K. Predicting Frequency from the External Chemical Environment: OH Vibrations on Hydrated and Hydroxylated Surfaces. J Chem Theory Comput 2022; 18:7683-7694. [PMID: 36458913 DOI: 10.1021/acs.jctc.2c00135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Robust correlation curves are essential to decipher structural information from IR-vibrational spectra. However, for surface-adsorbed water and hydroxides, few such correlations have been presented in the literature. In this paper, OH vibrational frequencies are correlated against 12 structural descriptors representing the quantum mechanical or geometrical environment, focusing on those external to the vibrating molecule. A nonbiased fitting procedure based on Gaussian process regression (GPR) was used alongside simple analytical functional forms. The training data consist of 217 structurally unique OH groups from 38 water/metal oxide interface systems for MgO, CaO and CeO2, all optimized at the DFT level, and the fully anharmonic and uncoupled OH vibrational signatures were calculated. Among our results, we find the following: (i) The intermolecular R(H···O) hydrogen bond distance is particularly strong, indicating the primary cause of the frequency shift. (ii) Similarly, the electric field along the H-bond vector is also a good descriptor. (iii) Highly detailed machine learning descriptors (ACSF, SOAP) are less intuitive but were found to be more capable descriptors. (iv) Combinations of geometric and QM descriptors give the best predictions, supplying complementary information.
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Affiliation(s)
- Andreas Röckert
- Department of Chemistry, Ångström Laboratory, Uppsala University, Uppsala751 21, Sweden
| | - Jolla Kullgren
- Department of Chemistry, Ångström Laboratory, Uppsala University, Uppsala751 21, Sweden
| | - Kersti Hermansson
- Department of Chemistry, Ångström Laboratory, Uppsala University, Uppsala751 21, Sweden
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Pushkar AP, Varghese JJ. Impact of surface-active site heterogeneity and surface hydroxylation in Ni doped ceria catalysts on oxidative dehydrogenation of propane. J Catal 2022. [DOI: 10.1016/j.jcat.2022.07.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Brugnoli L, Urata S, Pedone A. H 2O 2adsorption and dissociation on various CeO 2(111) surface models: a first-principles study. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:164006. [PMID: 35130519 DOI: 10.1088/1361-648x/ac5278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 02/07/2022] [Indexed: 06/14/2023]
Abstract
Periodic density functional theory (DFT) calculations using the hybrid PBE0 functional and atom-centered Gaussian functions as basis sets were carried out to investigate the absorption and the first steps involved in the decomposition of hydrogen peroxide (H2O2) on three different models of the ceria (111) surface. One of the models is a clean surface, and the others are defective and partially hydroxylated ceria surfaces. On the clean surface, we found that the minimum energy path of hydrogen peroxide decomposition involves a three-step process, i.e., adsorption, deprotonation, and formation of the peroxide anion, stabilized through its interaction with the surface at a Ce (IV) site, with activation barriers of less than about 0.5 eV. The subsequent formation of superoxide anions and molecular oxygen species is attributed to electron transfer from the reactants to the Ce (IV) ions underneath. On the defective surface, H2O2dissociation is an energetically downhill reaction thermodynamically driven by the healing of the O vacancies, after the reduction and decomposition of H2O2into oxygen and water. On the hydroxylated surface, H2O2is first adsorbed by forming a favorable H-bond and then undergoes heterolytic dissociation, forming two hydroxyl groups at two vicinal Ce sites.
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Affiliation(s)
- Luca Brugnoli
- Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, via G. Campi 103, 41125 Modena, Italy
| | - Shingo Urata
- Planning Division, AGC Inc., Yokohama, Kanagawa 230-0045, Japan
| | - Alfonso Pedone
- Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, via G. Campi 103, 41125 Modena, Italy
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Insight of solvent effect on CeO2 catalyzed oxidation of styrene with tert-butyl hydroperoxide: A combined experimental and theoretical approach. CATAL COMMUN 2022. [DOI: 10.1016/j.catcom.2022.106413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Brugnoli L, Menziani MC, Urata S, Pedone A. Development and Application of a ReaxFF Reactive Force Field for Cerium Oxide/Water Interfaces. J Phys Chem A 2021; 125:5693-5708. [PMID: 34152149 DOI: 10.1021/acs.jpca.1c04078] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ceria (CeO2) is a well-known catalytic oxide with many environmental, energy production, and industrial applications, most of them involving water as a reactant, byproduct, solvent, or simple spectator. In this work, we parameterized a Ce/O/H ReaxFF for the study of ceria and ceria/water interfaces. The parameters were fitted to an ab initio training set obtained at the DFT/PBE0 level, including the structures, cohesive energies, and elastic properties of the crystalline phases Ce, CeO2, and Ce2O3; the O-defective structures and energies of vacancy formation on CeO2 bulk and CeO2 (111) surface, as well as the absorption and reaction energies of H2 and H2O molecules on CeO2 (111). The new potential reproduced reasonably well all the fitted properties as well as the relative stabilities of the different ceria surfaces, the oxygen vacancies formation, and the energies and structures of associative and dissociative water molecules on them. Molecular dynamics simulations of the liquid water on the CeO2 (111) and CeO2 (100) surfaces were carried out to study the coverage and the mechanism of water dissociation. After equilibration, on average, 35% of surface sites of CeO2 (111) are hydroxylated whereas 15% of them are saturated with molecular water associatively adsorbed. As for the CeO2 (100) surface, we observed that water preferentially dissociates covering 90% of the available surface sites in excellent agreement with recent experimental findings.
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Affiliation(s)
- Luca Brugnoli
- Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, via G. Campi 103, Modena 41125, , Italy
| | - Maria Cristina Menziani
- Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, via G. Campi 103, Modena 41125, , Italy
| | - Shingo Urata
- Innovative Technology Laboratories, AGC Inc., Yokohama, Kanagawa 230-0045, Japan
| | - Alfonso Pedone
- Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, via G. Campi 103, Modena 41125, , Italy
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Xu Y, Mofarah SS, Mehmood R, Cazorla C, Koshy P, Sorrell CC. Design strategies for ceria nanomaterials: untangling key mechanistic concepts. MATERIALS HORIZONS 2021; 8:102-123. [PMID: 34821292 DOI: 10.1039/d0mh00654h] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The morphologies of ceria nanocrystals play an essential role in determining their redox and catalytic performances in many applications, yet the effects of synthesis variables on the formation of ceria nanoparticles of different morphologies and their related growth mechanisms have not been systematised. The design of these morphologies is underpinned by a range of fundamental parameters, including crystallography, optical mineralogy, the stabilities of exposed crystallographic planes, CeO2-x stoichiometry, phase equilibria, thermodynamics, defect equilibria, and the crystal growth mechanisms. These features are formalised and the key analytical methods used for analysing defects, particularly the critical oxygen vacancies, are surveyed, with the aim of providing a source of design parameters for the synthesis of nanocrystals, specifically CeO2-x. However, the most important aspect in the design of CeO2-x nanocrystals is an understanding of the roles of the main variables used for synthesis. While there is a substantial body of data on CeO2-x morphologies fabricated using low cerium concentrations ([Ce]) under different experimental conditions, the present work fully maps the effects of the relevant variables on the resultant CeO2-x morphologies in terms of the commonly used raw materials [Ce] (and [NO3-] in Ce(NO3)3·6H2O) as feedstock, [NaOH] as precipitating agent, temperature, and time (as well as the complementary vapour pressure). Through the combination of consideration of the published literature and the generation of key experimental data to fill in the gaps, a complete mechanistic description of the development of the main CeO2-x morphologies is illustrated. Further, the mechanisms of the conversion of nanochains into the two variants of nanorods, square and hexagonal, have been elucidated through crystallographic reasoning. Other key conclusions for the crystal growth process are the critical roles of (1) the formation of Ce(OH)4 crystallite nanochains as the precursors of nanorods and (2) the disassembly of the nanorods into Ce(OH)4 crystallites and NO3--assisted reassembly into nanocubes (and nanospheres) as an unrecognised intermediate stage of crystal growth.
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Affiliation(s)
- Yuwen Xu
- School of Materials Science and Engineering, UNSW Sydney, Australia.
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Baker LR, Diebold U, Park JY, Selloni A. Oxide chemistry and catalysis. J Chem Phys 2020; 153:050401. [DOI: 10.1063/5.0021819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- L. Robert Baker
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43221, USA
| | - Ulrike Diebold
- Institute of Applied Physics, TU Wien, 1040 Vienna, Austria
| | - Jeong Young Park
- Department of Chemistry, KAIST, Daejeon 34141, South Korea
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science, Daejeon 34141, South Korea
| | - Annabella Selloni
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
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