High performance n+p-Si/Ti/NiS O 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/NiSxOy photocathode 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+p-Si/Ti/NiSxOy. This work offers a novel strategy for effectively integrating electrocatalysts with semiconductor to design efficient photoelectrode toward PEC water splitting.