Efficient Electron Transfer across a ZnO-MoS₂ -Reduced Graphene Oxide Heterojunction for Enhanced Sunlight-Driven...

The development of noble metal-free catalysts for hydrogen evolution is required for energy applications. In this regard, ternary heterojunction nanocomposites consisting of ZnO nanoparticles anchored on MoS₂ -RGO (RGO=reduced graphene oxide) nanosheets as heterogeneous catalysts show highly efficient photocatalytic H₂ evolution. In the photocatalytic process, the catalyst dispersed in an electrolytic solution (S^2- and SO₃^2- ions) exhibits an enhanced rate of H₂ evolution, and optimization experiments reveal that ZnO with 4.0 wt % of MoS₂ -RGO nanosheets gives the highest photocatalytic H₂ production of 28.616 mmol h^-1  g_cat^-1 under sunlight irradiation; approximately 56 times higher than that on bare ZnO and several times higher than those of other ternary photocatalysts. The superior catalytic activity can be attributed to the in situ generation of ZnS, which leads to improved interfacial charge transfer to the MoS₂ cocatalyst and RGO, which has plenty of active sites available for photocatalytic reactions. Recycling experiments also proved the stability of the optimized photocatalyst. In addition, the ternary nanocomposite displayed multifunctional properties for hydrogen evolution activity under electrocatalytic and photoelectrocatalytic conditions owing to the high electrode-electrolyte contact area. Thus, the present work provides very useful insights for the development of inexpensive, multifunctional catalysts without noble metal loading to achieve a high rate of H₂ generation.