Nanostructured MoS3/WSe2 Thin-Film Photocathode for Efficient Water Splitting Under Light Illumination

The influence of the chemical state of a WO y thin-film precursor on formation of WSe 2 nanofilms under rapid selenization on a glassy carbon substrate at 900°C is studied. A nanolayer of amorphous molybdenum sulfide (MoS x ~ 3 ), which has high catalytic activity in the electrochemical reaction of hydrogen evolution, is applied onto the surface of the obtained WSe 2 films by pulsed laser deposition. It is shown that the composition of the WO y thin-film precursor has a significant effect on the morphology of the WSe 2 nanolayers, and this characteristic largely determines the efficiency of hydrogen evolution by the MoS 3 /WSe 2 heterostructure upon photoactivated water splitting. The most efficient hydrogen evolution is found for the MoS 3 /WSe 2 photocathode heterostructure containing WSe 2 in the form of crystal petals of ~50 nm in thickness, with these crystals oriented perpendicular to the substrate surface. A theoretical analysis of the possible effect of synergistic interaction at the MoS 3 /WSe 2 interface on the efficiency of hydrogen evolution is carried out. Density functional theory calculations have shown that MoS 3 clusters can increase the efficiency of the hydrogen evolution reaction upon contact with surface regions of WSe 2 nanocrystals different in atomic packing.