Morphology selective electrodeposition of Cu2O microcrystals on ZnO nanotube arrays as efficient visible-light-driven photo-electrode

Abstract ZnO nanotube arrays were synthesized by the electrodeposition method and Cu2O microcrystals with two kinds of morphologies were deposited on ZnO nanotube arrays successfully. At the deposition potential of −0.5 or −0.7 V, the cubic or spherical Cu2O microcrystals were selectively deposited on ZnO nanotube arrays. By adjusting the deposition time, Cu2O microcrystals with different sizes were obtained. The optical properties and photo-electrochemical performance of ZnO/Cu2O were measured. The results showed that the as-prepared ZnO/Cu2O heterojunction exhibited improved visible light absorption and enhanced photocurrent due to the excellent ability of Cu2O microcrystals for harvesting visible light, and the effective separation and transfer of photo-generated electrons and holes owing to p-n junction between ZnO and Cu2O. The experimental results demonstrate that the photo-electrochemical performance of ZnO/Cu2O heterojunction nanotube arrays can be manipulated by controlling the morphology and the size of Cu2O microcrystals.