Mechanism for hydrogen evolution from water splitting based on a MoS2/WSe2 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 MoS2 and WSe2, 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 MoS2/WSe2. The difference in work function led to the formation of a built-in electric field from WSe2 to MoS2, and the energy band alignment indicated that the redox reactions were located on the MoS2 and WSe2 semiconductors, respectively. The binding energy of MoS2 and WSe2 indicated that the thermodynamic properties of the heterogeneous structure were stable. MoS2 and WSe2 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 WSe2 and MoS2, which greatly improved the efficiency of hydrogen production by photocatalytic water splitting.