Mechanism of hydrogen generation on stable Mo-edge of 2H-MoS2 in water from density functional theory
In this paper, the stable structure of Mo-edge of 2H-MoS 2 in water and the H 2 evolution mechanism at Mo-edge in 2H-Mo 7 S 17 cluster were investigated by the B3LYP method of the density functional theory. The calculations suggested that the stable structure of the Mo-edge in gas and water was diff...
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Veröffentlicht in: | Theoretical chemistry accounts 2020-06, Vol.139 (6), Article 98 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | In this paper, the stable structure of Mo-edge of 2H-MoS
2
in water and the H
2
evolution mechanism at Mo-edge in 2H-Mo
7
S
17
cluster were investigated by the B3LYP method of the density functional theory. The calculations suggested that the stable structure of the Mo-edge in gas and water was different. The Mo-edge with the upright S bonded by one Mo atom was more stable in water while the S atom of Mo-edge was bonded by two Mo atoms to generate a stable Mo-edge in gas. The adsorption energy of H on S was higher than that on Mo at Mo-edge; as a result, the hydrogen evolution reactions on S and Mo were limited by the Heyrovsky and Volmer step, respectively. In hydrogen evolution reaction, the Volmer reaction occurs on S to produce Mo
7
S
17
H
S
, leading to the aggregation of electron on Mo and thus decreasing the barriers for H
2
evolution reaction on Mo. Subsequently, the Mo in Mo
7
S
17
H
S
severing as active sites efficiently catalyzed hydrogen evolution reaction through the Volmer–Heyrovsky mechanism, in which the Volmer reaction was identified as the rate-determining step with a potential barrier of 17.9 kcal/mol, being close to the experimental value of 19.9 kcal/mol. |
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ISSN: | 1432-881X 1432-2234 |
DOI: | 10.1007/s00214-020-02614-y |