Integration of a Cu₂O/ZnO heterojunction and Ag@SiO₂ into a photoanode for enhanced solar water oxidation

Photoelectrochemical water splitting (PEC-WS) has attracted considerable attention owing to its low energy consumption and sustainable nature. Constructing semiconductor heterojunctions with controllable band structure can effectively facilitate photogenerated carrier separation. In this study, a FTO/ZnO/Cu₂O/Ag@SiO₂ photoanode with a Cu₂O/ZnO p-n heterojunction and Ag@SiO₂ nanoparticles is constructed to investigate its PEC-WS performance. Compared with a bare ZnO photoanode, the photocurrent density of the FTO/ZnO/Cu₂O/Ag@SiO₂ photoanode (0.77 mA cm^-2) at 1.23 V_RHE exhibits an increment of 88%, and a cathodic shift of 0.1 V for the on-set potential (0.4 V_RHE). Detailed photoelectrochemical analyses reveal that the Cu₂O/ZnO p-n heterojunction formed between Cu₂O and ZnO can effectively promote photogenerated carrier separation. The surface plasmonic effect of the Ag@SiO₂ nanoparticles can further promote the photogenerated carrier transfer efficiency, which synergistically improves the PEC-WS performance.