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
Hauptverfasser: Han, Yan-Xia, Kong, Chao, Yan, Pen-Ji
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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.
ISSN:1432-881X
1432-2234
DOI:10.1007/s00214-020-02614-y