Single-Step Electrodeposition of ZnO Nanoparticles Decorated (111)-Textured Cu2O Films with Enhanced Photoelectrochemical Properties

Cuprous oxide (Cu2O) is a promising material for photoelectrochemical water splitting due to its favorable band structure, environmental acceptability, nontoxicity, and ease of fabrication. In this study, (111)-textured Cu2O films decorated with numerous ZnO nanoparticles (NPs), namely ZCO films, are synthesized by a facile one-step electrodeposition method. The mechanism for forming ZnO NPs during the electrodeposition of Cu2O films is proposed. Based on the Mott–Schottky analysis and electrochemical impedance spectroscopy measurements, the presence of ZnO NPs on the Cu2O films enhances band bending and reduces charge transfer resistance to the electrolyte, which is advantageous for separating photoexcited electron and hole carriers in the illuminated ZCO films. Additionally, excess oxygen vacancy defects may facilitate the interdefect hopping of photoelectrons by minimizing the recombination probability of transporting photocarriers within the ZCO films according to photoluminescence spectroscopy analysis. The ZCO film exhibits a 40% increase in photocurrent density over the pristine Cu2O film in 1 M Na2SO4 solution under AM1.5G illumination. This study provides a facile synthesis route for creating high-performance Cu2O-based photocathodes through heterojunction and crystal defect engineering.