Two-dimensional van der Waals nanocomposites as Z-scheme type photocatalysts for hydrogen production from overall water splitting

The Z-scheme is an efficient route for hydrogen production from photocatalytic water splitting; however, there is no theoretical design for two-dimensional (2D) systems. In the present work, the 2D van der Waals (vdW) MoSe2/graphene/HfS2 and MoSe2/N-doped graphene/HfS2 nanocomposites are proposed to be promising candidates for Z-scheme photocatalysts and verified by density functional theory calculations. The fine control of the n-type doping on graphene can enhance the efficiency of solar energy utilization. Furthermore, the 2D vdW MoSe2/HfS2 nanocomposite is shown to be a direct Z-scheme system for photocatalytic water splitting without redox mediators, which is more easily synthesized in experiment.