Transition metal-doped amorphous molybdenum sulfide/graphene ternary cocatalysts for excellent photocatalytic hydrogen evolution: Synergistic effect of transition metal and graphene

Abstract

Though amorphous molybdenum sulfide (MoSx) is considered a promising H2 evolution cocatalyst, its intrinsic activity and charge transfer efficiency are still unsatisfactory. To overcome these drawbacks, transition metal-doped (Fe, Co, or Ni) amorphous MoSx/graphene ternary nanocomposites were designed and fabricated using a one-step solvothermal method. Their structure, morphology, and properties were characterized. The metal-doped MoSx nanoparticles were well distributed on the graphene sheets in the ternary composites. Metal doping greatly enhanced the intrinsic activity of amorphous MoSx, and the integration of graphene notably promoted the separation of photoinduced carriers. The photocatalytic H2 evolution with amorphous MoSx as cocatalyst has been substantially improved under the synergistic effect of the transition metal and graphene. The H2 evolution rate of Co-doped amorphous MoSx/graphene composites reached 11.45 mmol·h−1·g−1 at the Co:Mo molar ratio of 2:3, which is 64% higher than that of Co-doped MoSx, 21 times that of undoped MoSx/graphene, and 127 times that of pure MoSx. This study would supply an efficient strategy and a new vision for developing excellent noble-metal-free photocatalysts for photocatalytic hydrogen production.