Synergistic coupling of tri-metallic Fe,Ni,Co(oxy)hydroxide with WO3/W Schottky junctions for enhancing photoelectrochemical seawater oxidation

Enhancing charge separation, transport efficiency, and long-term stability is critical for achieving effective photoelectrochemical (PEC) seawater oxidation. WO3/W Schottky junctions, widely studied as photoanodes, are hindered by high interfacial recombination rate, low conversion efficiency, and instability in seawater. To overcome these challenges, we introduced multi-metallic (oxy)hydroxide layers to the photoanodes. Active sites for oxidation reactions were provided by Fe, Co, and Ni, while interfacial coordination bonds between the (oxy) hydroxide layer and WO3 enhanced hole extraction and facilitated oxidation. The CoOOH layer served as a protective barrier, enabling over 10 h of stability in corrosive seawater. The designed photoanode delivered a photocurrent of 4.85mAcm-2 at 1.23 V vs. RHE, 6.8 times higher than WO3/W, with a photon-to-current efficiencyof 74.1 % at 400 nm. Our findings unlock possibilities for the development of heterostructured photoanodes and design of advanced PEC catalysts for efficientsolar energy harvesting from seawater.