Mechanism for hydrogen evolution from water splitting based on a MoS 2 /WSe 2 heterojunction photocatalyst: a first-principle study.

In this study, density functional theory and hybrid functional theory are used to calculate the work function and energy band structure of MoS 2 and WSe 2 , as well as the binding energy, work function, energy band structure, density of states, charge density difference, energy band alignment, Bader charge, and H adsorption free energy of MoS 2 /WSe 2 . The difference in work function led to the formation of a built-in electric field from WSe 2 to MoS 2 , and the energy band alignment indicated that the redox reactions were located on the MoS 2 and WSe 2 semiconductors, respectively. The binding energy of MoS 2 and WSe 2 indicated that the thermodynamic properties of the heterogeneous structure were stable. MoS 2 and WSe 2 gathered electrons and holes, respectively, and redistributed them under the action of the built-in electric field. The photogenerated electrons and holes were enriched on the surface of WSe 2 and MoS 2 , which greatly improved the efficiency of hydrogen production by photocatalytic water splitting.