Architecture lattice-matched cauliflower-like CuO/ZnO p–n heterojunction toward efficient water splitting

BACKGROUND: In photoelectrochemical (PEC) water splitting, hydrogen and oxygen can be dissociated from water molecules on semiconductors by directly utilizing clean renewable solar energy. The key bottleneck of PEC water splitting is to design new types of photoelectrodes with long-term stability and high PEC performance. RESULTS: Here, cauliflower-shaped p–n CuO/ZnO heterojunction photocathodes with lattice matching were synthesized using one-step electrodeposition and heat treatment. The results showed that the deposition of CuO and ZnO took place simultaneously. The proportion of CuO and ZnO varied with the electrodeposition time and calcination temperature and duration. The parallel lattice-matched CuO/ZnO heterojunction enhanced the separation and migration of photogenerated charge carriers, which accomplished a photocurrent density value of approximately −1.8 mA cm⁻² at a bias of 0 V_RHE in 0.5 mol L⁻¹ Na₂SO₄ solution. CONCLUSIONS: This work could provide a simplified strategy for the synthesis of p–n copper-based heterogeneous photocathodes for application in PEC water splitting.