In situ integration of a cocatalyst and heterojunction to a WO 3 photoanode with enhanced photoelectrochemical performance via phosphatization

A novel ternary NiP x /NiWO 4 /WO 3 photoanode with the cooperation effect of a heterojunction and cocatalyst was successfully fabricated by an in situ phosphatization process. The NiWO 4 layer forms a heterojunction with WO 3 to improve the separation and transfer of electron–hole pairs. NiP x acts as a cocatalyst for accelerating the surface water oxidation reaction. A 2.55-fold improvement in photocurrent density at 1.23 V vs. RHE was achieved compared with the pristine WO 3 film.