ZnSe/CdS/CdSe triple-sensitized ZnO nanowire arrays for multi-bandgap photoelectrochemical hydrogen generation

Since the discovery of hydrogen evolution through the photoelectrochemical (PEC) splitting of water from n-type TiO2 electrodes, the technology of short-bandgap semiconductors (such as ZnSe, CdS and CdSe) combined with one-dimensional (1D) metal-oxide nanowire (NW) arrays (e.g., TiO2 and ZnO) to enhance their visible-light harvest efficiency has been widely studied. In this study, ZnSe/CdS/CdSe triple-sensitized ZnO NW arrays were successfully fabricated on FTO substrates via a facile hydrothermal and anion exchange reaction, followed by a chemical bath deposition (CBD) approach. Through the effective synergistic light absorption of the solar energy and the multi-type-II graded bandgap level between the core ZnO NW and the different photosensitization out layers in these composite nanostructures, a remarkable enhancement in photochemical conversion performance was achieved. The morphogenetic strategy used for the material production in this work is low-cost but effective, and it could be extended to prepare other core-multishell nanostructures with elaborate textural characteristics.