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 WS x onto Si photocathode. The controllable WS x 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/WS x /Si photocathode exhibits an onset potential of + 0.47 V vs. reversible hydrogen electrode (V RHE ), a photocurrent density of − 25.1 mA cm −2 at 0 V RHE , and superior durability of up to 300 h at 0 V RHE in 1.0 M KOH electrolyte. These findings offer a facile and effective approach for the further development of durable Si-based photoelectrochemical devices. • An integration of WS x -protected Si photocathode with Co-P cocatalyst was designed. • The WS x thin-film could ensure the alkali-corrosion resistance of Si photocathodes. • The anti-reflective effect of Co-P cocatalyst was induced via the controllable WS x . • A Co-P/WS x /Si photocathode displayed durable PEC-HER performance in alkaline media. • The proposed synergetic strategy exhibited a great potentiality for PEC HER.