Organic Dye Molecules Sensitization-Enhanced Photocatalytic Water-Splitting Activity of MoS2 from First-Principles Calculations

The monolayer MoS2 (ML-MoS2) is a direct gap semiconductor that exposes good optical absorption in the visible region and good stability in an acidic environment. However, its conduction band minimum is below the hydrogen redox potential of water, which greatly limits the application of ML-MoS2 in photoelectrocatalytic water-splitting. To rationalize applicable photocatalytic water-splitting performance of MoS2, we theoretically proposed a strategy by sensitizing ML-MoS2 with an organic dye molecule. It is found that organic dye molecule sensitization not only can promote the population of photogenerated electron-hole pairs available for photocatalysis but also can effectively tune the band edge positions of MoS2 to meet the requirement of photocatalytic hydrogen production. The shift of the band edge stems from the interaction between the intrinsic dipole of the dye molecules and the induced dipole at the dye-MoS2 interface. We propose that the dye molecules-MoS2-graphene hybrids are good candidates for use as photocatalysts in the splitting of water for hydrogen generation because of their matched band alignment, ideal optical absorption, and good stability. We hope that our findings will stimulate experiment efforts to develop new photocatalysts based on sensitized MoS2.