Cactus-like hierarchical nanorod-nanosheet mixed dimensional photoanode for efficient and stable water splitting

A novel hierarchical ZnO nanorod-nanosheet mixed dimensional nanoarchitecture modified with CdS quantum dots and Ni(OH)2 catalyst was designed as photoanode for photoelectrochemical water splitting. The FDTD simulation results demonstrated the better light utilization efficiency for the proposed novel mixed 2D/1D hierarchical structure and subsequently resulted in larger effective heterostructure interface area of photoanode which means the increased heterostructure interface area while maintaining evenly distributed light absorption especially at the bottom zone of 3D nanostructure. The applied bias photo-to-current efficiency of H-ZnO/CdS/Ni(OH)2 reached 4.12%, 20.6 times that of ZnO nanosheets photoanode. More importantly, the efficient hole consumption characteristic of Ni(OH)2 catalyst introduced the significantly improved photoelectrochemical stability. In such mixed dimensional hierarchical nanoarchitecture, each component contributed synergistically to the enhanced PEC performance, and this novel design may give impetus to promote the efficient and stable hydrogen generation via PEC water splitting.