A synergetic strategy to construct anti-reflective and anti-corrosive Co-P/WSx/Si photocathode for durable hydrogen evolution in alkaline condition

Developing durable Si-based photoelectrochemical hydrogen evolution reaction in alkaline media is attracting attention in device-level water splitting, but still faces a trade-off between the alkalic corrosion resistance and light transmission for Si photocathodes. Herein, a synergetic strategy is proposed to employ an anti-reflective Co-P film cocatalyst modulated via self-assembly of protective-layer WSx onto Si photocathode. The controllable WSx thin-film efficiently ensures the excellent anti-alkali corrosion of Si semiconductors, and serves as an appropriate nucleation base to modulate the structure of Co-P cocatalyst to possess anti-reflection. The optimal Co-P/WSx/Si photocathode exhibits an onset potential of + 0.47 V vs. reversible hydrogen electrode (VRHE), a photocurrent density of − 25.1 mA cm−2 at 0 VRHE, and superior durability of up to 300 h at 0 VRHE in 1.0 M KOH electrolyte. These findings offer a facile and effective approach for the further development of durable Si-based photoelectrochemical devices. [Display omitted] •An integration of WSx-protected Si photocathode with Co-P cocatalyst was designed.•The WSx thin-film could ensure the alkali-corrosion resistance of Si photocathodes.•The anti-reflective effect of Co-P cocatalyst was induced via the controllable WSx.•A Co-P/WSx/Si photocathode displayed durable PEC-HER performance in alkaline media.•The proposed synergetic strategy exhibited a great potentiality for PEC HER.