High performance np-Si/Ti/NiSO photocathode for photoelectrochemical hydrogen evolution in alkaline solution

Silicon, as a promising semiconductor for fabricating photocathode toward photoelectrochemical hydrogen evolution reaction（PEC-HER）, should be improved in light harvesting ability and catalytic kinetics to obtain high PEC performance. Herein, a novel amorphous Nickel Oxysulfide（NiSxOy） film is effectively integrated with a Ti protected n+p-Si micropyramid photocathode by the electrodeposition method. The fabricated n+p-Si/Ti/Ni SxOyphotocathode exhibits excellent PEC-HER performance with an onset potential of 0.5 V（at J =-0.1 mA/cm2）, a photocurrent density of-26 mA/cm2 at 0 V vs. RHE, and long term stability of six hours in alkaline solution（pH ≈ 14）. The synergy of unique n+p-Si micropyramid architectures（omnidirectional broadband light harvesting ability）, novel amorphous NiSxOy catalyst（high HER electrocatalytic activity and good optical transparency） results in the high performance of n+pSi/Ti/Ni SxOy. This work offers a novel strategy for effectively integrating electrocatalysts with semiconductor to design efficient photoelectrode toward PEC water splitting.