Boosting photoelectrochemical water splitting performance of Ta₃N₅ nanorod array photoanodes by forming a dual co-catalyst shell

Concerning both the activity and stability of the promising solar-driven Ta₃N₅-based photoanodes for photoelectrochemical water splitting, the strategy for simultaneously promoting charge separation, enhancing catalytic activity and also improving the resistance to self-oxidation is highly desirable and actively pursued. In this study, a novel dual co-catalyst shell consisting of a continuous CoPi layer at the bottom and many non-continuous Co(OH)₂ islands at the top of the CoPi layer is designed to meet the strict requirements for efficient Ta₃N₅ photoanodes. As a result of the synergistic effects of such a shell in collectively addressing the concerns, the constructed photoanode of CoPi/Co(OH)₂-Ta₃N₅ nanorod arrays show the remarkably enhanced photoelectrochemical water splitting performance compared with the photoanodes with single co-catalyst. The results demonstrated in this study are expected to shed some light on constructing efficient photoelectrodes of the light absorbers that have wide absorption range but low resistance to self-oxidation.