Abstract
Cuprous oxide is a promising photocathode for solar hydrogen production, but its planar form is limited by short charge-carrier diffusion length.To overcome these challenges, we grew Cu2O as nanowire arrays and added a ZnO overlayer, creating a robust three-dimensional Cu2O/ZnO heterostructure.We developed a straightforward method to electrodeposit Cu2O nanowires on a copper-seeded transparent electrode, followed by spin-coating ZnO seed layers and hydrothermal growth of ZnO nanowires around the Cu2O.This Cu2O/ZnO architecture dramatically improved photoelectrochemical performance.Under simulated sunlight, Cu2O nanowires delivered more than three times the photocurrent of a planar Cu2O film (1.3 vs 0.4 mA/cm 2 at 0 V vs RHE).Adding the ZnO shell further raised the photocurrent to 1.75 mA/cm 2 and shielded the Cu2O, facilitating charge separation at the p-n junction.The nanowire morphology provides a higher surface area and shorter charge transport pathways, which together boost light absorption and suppress recombination.These results highlight an effective, scalable strategy to improve Cu2O-based photocathodes, demonstrating how nanostructuring and heterojunction layers can yield more efficient and stable devices for solar fuel generation.