Full atomistic reaction mechanism with kinetics for CO reduction on Cu(100) from ab initio molecular dynamics free-energy calculations at 298 K
A critical step toward the rational design of new catalysts that achieve selective and efficient reduction of CO^sub 2^ to specific hydrocarbons and oxygenates is to determine the detailed reaction mechanism including kinetics and product selectivity as a function of pH and applied potential for known systems. To accomplish this, we apply ab initio molecular metadynamics simulations (AIMμD) for the water/Cu(100) system with five layers of the explicit solvent under a potential of -0.59 V [reversible hydrogen electrode (RHE)] at pH 7 and compare with experiment. From these free-energy calculations, we determined the kinetics and pathways for major products (ethylene and methane) and minor products (ethanol, glyoxal, glycolaldehyde, ethylene glycol, acetaldehyde, ethane, and methanol). For an applied potential (U) greater than -0.6 V (RHE) ethylene, the major product, is produced via the Eley-Rideal (ER) mechanism using H^sub 2^O + e-. The rate-determining step (RDS) is C-C coupling of two CO, with ΔG^sup [double dagger]^ = 0.69 eV. For an applied potential less than -0.60 V (RHE), the rate of ethylene formation decreases, mainly due to the loss of CO surface sites, which are replaced by H*. The reappearance of C^sub 2^H^sub 4^ along with CH^sub 4^ at U less than -0.85 V arises from *CHO formation produced via an ER process of H* with nonadsorbed CO (a unique result). This *CHO is the common intermediate for the formation of both CH^sub 4^ and C^sub 2^H^sub 4^. These results suggest that, to obtain hydrocarbon products selectively and efficiency at pH 7, we need to increase the CO concentration by changing the solvent or alloying the surface..
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Artikel |
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Erscheinungsjahr: |
2017 |
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Erschienen: |
2017 |
Enthalten in: |
Zur Gesamtaufnahme - volume:114 |
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Enthalten in: |
Proceedings of the National Academy of Sciences of the United States of America - 114(2017), 8, Seite 1795 |
Sprache: |
Englisch |
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Beteiligte Personen: |
Cheng, Tao [VerfasserIn] |
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Links: |
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doi: |
10.1073/pnas.1612106114 |
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funding: |
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Förderinstitution / Projekttitel: |
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PPN (Katalog-ID): |
OLC1993656332 |
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245 | 1 | 0 | |a Full atomistic reaction mechanism with kinetics for CO reduction on Cu(100) from ab initio molecular dynamics free-energy calculations at 298 K |
264 | 1 | |c 2017 | |
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520 | |a A critical step toward the rational design of new catalysts that achieve selective and efficient reduction of CO^sub 2^ to specific hydrocarbons and oxygenates is to determine the detailed reaction mechanism including kinetics and product selectivity as a function of pH and applied potential for known systems. To accomplish this, we apply ab initio molecular metadynamics simulations (AIMμD) for the water/Cu(100) system with five layers of the explicit solvent under a potential of -0.59 V [reversible hydrogen electrode (RHE)] at pH 7 and compare with experiment. From these free-energy calculations, we determined the kinetics and pathways for major products (ethylene and methane) and minor products (ethanol, glyoxal, glycolaldehyde, ethylene glycol, acetaldehyde, ethane, and methanol). For an applied potential (U) greater than -0.6 V (RHE) ethylene, the major product, is produced via the Eley-Rideal (ER) mechanism using H^sub 2^O + e-. The rate-determining step (RDS) is C-C coupling of two CO, with ΔG^sup [double dagger]^ = 0.69 eV. For an applied potential less than -0.60 V (RHE), the rate of ethylene formation decreases, mainly due to the loss of CO surface sites, which are replaced by H*. The reappearance of C^sub 2^H^sub 4^ along with CH^sub 4^ at U less than -0.85 V arises from *CHO formation produced via an ER process of H* with nonadsorbed CO (a unique result). This *CHO is the common intermediate for the formation of both CH^sub 4^ and C^sub 2^H^sub 4^. These results suggest that, to obtain hydrocarbon products selectively and efficiency at pH 7, we need to increase the CO concentration by changing the solvent or alloying the surface. | ||
650 | 4 | |a Carbon monoxide | |
650 | 4 | |a Oxidation-reduction reaction | |
650 | 4 | |a Chemical reaction, Rate of | |
650 | 4 | |a Molecular dynamics | |
650 | 4 | |a Observations | |
650 | 4 | |a Copper | |
650 | 4 | |a Chemical properties | |
650 | 4 | |a Molecular chemistry | |
650 | 4 | |a Reaction kinetics | |
650 | 4 | |a Electrocatalysis | |
650 | 4 | |a Hydrocarbons | |
650 | 4 | |a Electrodes | |
650 | 4 | |a Antifreeze solutions | |
650 | 4 | |a Solvent extraction processes | |
700 | 1 | |a Xiao, Hai |4 oth | |
700 | 1 | |a Goddard, William A |4 oth | |
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773 | 1 | 8 | |g volume:114 |g year:2017 |g number:8 |g pages:1795 |
856 | 4 | 1 | |u http://dx.doi.org/10.1073/pnas.1612106114 |3 Volltext |
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