Synthesis of Cu₂O/ZnO hetero-nanorod arrays with enhanced visible light-driven photocatalytic activity

Vertically aligned Cu₂O/ZnO hetero-nanorod arrays were synthesized on indium-doped tin oxide (ITO) glass substrates using a simple hydrothermal method followed by an electrodeposition process. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) results show that Cu₂O nanoparticles conformably formed on the pre-grown ZnO single-crystalline nanorods. Compared to pure Cu₂O and pure ZnO nanorod array films, the Cu₂O/ZnO hetero-nanorod array films exhibit an excellent improvement in photocatalytic applications under visible light irradiation. The increase of the electrodeposition time (amount) of Cu₂O helps to enhance the photocatalytic activities of the system until the Cu₂O nanoparticles nearly cover the entire periphery of the ZnO nanorods. The enhanced photocatalytic activity is attributed to better light scattering for the Cu₂O/ZnO hetero-nanorod array structure and fast charge separation and transport within the heterojunctions of the Cu ₂O/ZnO.