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Bunting RJ, Caffrey NM. The effects of polymorphism and lithium intercalation on the hydrogen evolution reaction for the basal planes of MoS2. J Chem Phys 2023; 159:144703. [PMID: 37811822 DOI: 10.1063/5.0160420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 09/25/2023] [Indexed: 10/10/2023] Open
Abstract
The activity of Li-intercalated MoS2 phases for the hydrogen evolution reaction is investigated using density functional theory. The most stable semiconducting 2H phase, the metallic 1T' phase, and a polymorphous surface composed of alternating H and T' phases (1T″) are investigated. The local structure of the MoS2 surface is found to define its reactivity. In all cases, active sites for the hydrogen evolution process are restricted to T-like sulphur sites. Li-intercalation is found to promote hydrogen evolution reaction reactivity for the H phase whilst having little effect on the T phase. While improved compared to the non-intercalated phase, the Li-intercalated H phase MoS2 still has minimal activity for the hydrogen evolution reaction. The same effect of intercalation is also found for another transition metal dichalcogenide, MoSe2. The ability to improve reactivity in this way makes ion intercalation a promising space for designing new 2D catalysts for the hydrogen evolution reaction.
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Affiliation(s)
- Rhys J Bunting
- School of Physics, O'Brien Centre for Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Nuala M Caffrey
- School of Physics, O'Brien Centre for Science, University College Dublin, Belfield, Dublin 4, Ireland
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Abstract
Physical catalysts often have multiple sites where reactions can take place. One prominent example is single-atom alloys, where the reactive dopant atoms can preferentially locate in the bulk or at different sites on the surface of the nanoparticle. However, ab initio modeling of catalysts usually only considers one site of the catalyst, neglecting the effects of multiple sites. Here, nanoparticles of copper doped with single-atom rhodium or palladium are modeled for the dehydrogenation of propane. Single-atom alloy nanoparticles are simulated at 400-600 K, using machine learning potentials trained on density functional theory calculations, and then the occupation of different single-atom active sites is identified using a similarity kernel. Further, the turnover frequency for all possible sites is calculated for propane dehydrogenation to propene through microkinetic modeling using density functional theory calculations. The total turnover frequencies of the whole nanoparticle are then described from both the population and the individual turnover frequency of each site. Under operating conditions, rhodium as a dopant is found to almost exclusively occupy (111) surface sites while palladium as a dopant occupies a greater variety of facets. Undercoordinated dopant surface sites are found to tend to be more reactive for propane dehydrogenation compared to the (111) surface. It is found that considering the dynamics of the single-atom alloy nanoparticle has a profound effect on the calculated catalytic activity of single-atom alloys by several orders of magnitude.
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Affiliation(s)
- Rhys J Bunting
- Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria
| | - Felix Wodaczek
- Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria
| | - Tina Torabi
- Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria
| | - Bingqing Cheng
- Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria
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Bunting RJ, Rice PS, Yao Z, Thompson J, Hu P. Understanding and tackling the activity and selectivity issues for methane to methanol using single atom alloys. Chem Commun (Camb) 2022; 58:9622-9625. [PMID: 35942706 DOI: 10.1039/d2cc03183c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The process for the direct oxidation of methane to methanol is investigated on single atom alloys using density functional theory. A catalyst search is performed across FCC metal single atom alloys. 7 single atom alloys are found as candidates and microkinetic modelling is performed. The activity and selectivity are remarkably improved over that of pure palladium metal, yet remain unideal.
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Affiliation(s)
- Rhys J Bunting
- School of Chemistry and Chemical Engineering, Queen's University Belfast, David Keir Building, Stranmillis Road, Belfast, BT9 5AG, UK.
| | - Peter S Rice
- School of Chemistry and Chemical Engineering, Queen's University Belfast, David Keir Building, Stranmillis Road, Belfast, BT9 5AG, UK.
| | - Zihao Yao
- School of Chemistry and Chemical Engineering, Queen's University Belfast, David Keir Building, Stranmillis Road, Belfast, BT9 5AG, UK.
| | - Jillian Thompson
- School of Chemistry and Chemical Engineering, Queen's University Belfast, David Keir Building, Stranmillis Road, Belfast, BT9 5AG, UK.
| | - P Hu
- School of Chemistry and Chemical Engineering, Queen's University Belfast, David Keir Building, Stranmillis Road, Belfast, BT9 5AG, UK.
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Bunting RJ, Rice PS, Thompson J, Hu P. Investigating the innate selectivity issues of methane to methanol: consideration of an aqueous environment. Chem Sci 2021; 12:4443-4449. [PMID: 34163709 PMCID: PMC8179483 DOI: 10.1039/d0sc05402j] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 02/01/2021] [Indexed: 01/14/2023] Open
Abstract
The higher reactivity of the methanol product over the methane reactant for the direct oxidation of methane to methanol is explored. C-H activation, C-O coupling, and C-OH coupling are investigated as key steps in the selective oxidation of methane using DFT. These elementary steps are initially considered in the gas phase for a variety of fcc (111) pristine metal surfaces. Methanol is found to be consistently more reactive for both C-H activation and subsequent oxidation steps. With an aqueous environment being understood experimentally to have a profound effect on the selectivity of this process, these steps are also considered in the aqueous phase by ab initio molecular dynamics calculations. The water solvent is modelled explicity, with each water molecule given the same level of theory as the metal surface and surface species. Free energy profiles for these steps are generated by umbrella sampling. It is found that an aqueous environment has a considerable effect on the kinetics of the elementary steps yet has little effect on the methane/methanol selectivity-conversion limit. Despite this, we find that the aqueous phase promotes the C-OH pathway for methanol formation, which could enhance the selectivity for methanol formation over that of other oxygenates.
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Affiliation(s)
- Rhys J Bunting
- School of Chemistry and Chemical Engineering, Queen's University Belfast David Keir Building Stranmillis Road Belfast BT9 5AG UK
| | - Peter S Rice
- School of Chemistry and Chemical Engineering, Queen's University Belfast David Keir Building Stranmillis Road Belfast BT9 5AG UK
| | - Jillian Thompson
- School of Chemistry and Chemical Engineering, Queen's University Belfast David Keir Building Stranmillis Road Belfast BT9 5AG UK
| | - P Hu
- School of Chemistry and Chemical Engineering, Queen's University Belfast David Keir Building Stranmillis Road Belfast BT9 5AG UK
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Yao Z, Zhao J, Bunting RJ, Zhao C, Hu P, Wang J. Quantitative Insights into the Reaction Mechanism for the Direct Synthesis of H2O2 over Transition Metals: Coverage-Dependent Microkinetic Modeling. ACS Catal 2021. [DOI: 10.1021/acscatal.0c04125] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Zihao Yao
- Institute of Industrial Catalysis, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310032, People’s Republic of China
| | - Jinyan Zhao
- Institute of Industrial Catalysis, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310032, People’s Republic of China
| | - Rhys J. Bunting
- School of Chemistry and Chemical Engineering, The Queen’s University of Belfast, Belfast BT9 5AG, U.K
| | - Chenxia Zhao
- Institute of Industrial Catalysis, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310032, People’s Republic of China
| | - Peijun Hu
- School of Chemistry and Chemical Engineering, The Queen’s University of Belfast, Belfast BT9 5AG, U.K
| | - Jianguo Wang
- Institute of Industrial Catalysis, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310032, People’s Republic of China
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Bunting RJ, Thompson J, Hu P. The mechanism and ligand effects of single atom rhodium supported on ZSM-5 for the selective oxidation of methane to methanol. Phys Chem Chem Phys 2020; 22:11686-11694. [PMID: 32406892 DOI: 10.1039/d0cp01284j] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The mechanism for the partial oxidation of methane to methanol on single atom rhodium supported on ZSM-5 is investigated by DFT. The most favoured mechanism for methane activation is shown to be via oxidative addition at an undercoordinated rhodium metal centre and not through a typical metal oxo intermediate. The formation of a C-OH bond, and not methane activation, is found to be the rate determining step. CO coordinated to the rhodium centre is observed to strongly promote this bond formation. Water is required in the system to help prevent catalyst poisoning by CO, which greatly hinders the methane activation step, and to protonate an intermediate RhOOH species. These results suggest that more focus is required on methyl-oxygen bond formation and that exclusive consideration of methane activation will not completely explain some methane partial oxidation systems.
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Affiliation(s)
- Rhys J Bunting
- School of Chemistry and Chemical Engineering, Queen's University Belfast, David Keir Building, Stranmillis Road, Belfast BT9 5AG, UK.
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Affiliation(s)
- Rhys J. Bunting
- School of Chemistry and Chemical Engineering, Queen’s University Belfast, David Keir Building, Stranmillis Road, Belfast BT9 5AG, U.K
| | - Xiran Cheng
- School of Chemistry and Chemical Engineering, Queen’s University Belfast, David Keir Building, Stranmillis Road, Belfast BT9 5AG, U.K
| | - Jillian Thompson
- School of Chemistry and Chemical Engineering, Queen’s University Belfast, David Keir Building, Stranmillis Road, Belfast BT9 5AG, U.K
| | - P. Hu
- School of Chemistry and Chemical Engineering, Queen’s University Belfast, David Keir Building, Stranmillis Road, Belfast BT9 5AG, U.K
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