Preparation and photoelectrochemical properties of hierarchical heterostructure ZnO/CuO array

In this paper, a ZnO array is first prepared on the conductive glass by hydrothermal method, and then a seed layer of CuO nanoparticles is deposited on the surface of ZnO nanorods to form a core–shell ZnO/CuO nanoarray. Following, the dendritic CuO nanorods are grown on ZnO nanorods by hydrothermal method, constructing a three-dimensional ZnO/CuO nano-heterogeneous hierarchical structure array and applied in photoelectrochemical cell. Our three-dimensional ZnO/CuO nano-heterogeneous hierarchical structure shows obvious absorption of visible light from 500 to 900 nm. The current–time curves reveal that the photocurrent is greatly enhanced after dendritic CuO grows on the ZnO nanorod array. Furthermore, the charge dynamics processes in the core–shell ZnO/CuO nano-heterostructure array and the three-dimensional ZnO/CuO nano-heterostructure array are studied by comparing electrochemical impedance spectroscopy and intensity modulation photocurrent (photovoltage) spectroscopy. Although the photo-generated charge transfer rate in the ZnO/CuO core–shell structure is slightly faster than the three-dimensional ZnO/CuO hierarchical structure, the recombination life of the photo-generated charge is increased by nearly two orders of magnitude in the three-dimensional ZnO/CuO nano-heterostructure array. The three-dimensional ZnO/CuO nano-heterostructure array has a good potential application in the field of photoelectric conversion devices and photocatalysis.