Strategy to Achieve Augmented Photoelectrochemical Water Oxidation via Heteroband Structure Engineering and In Situ Interface Activation.

A simple strategy to achieve remarkable activity of photoelectrochemical (PEC) water oxidation is both a critical requirement prior to accelerating the deployment of hydrogen and an important pursuit for renewable solar energy utilization. Despite various ways to improve the PEC performance, laborious fabrication and a statically driven process for water oxidation are still the most challenging tasks. We, herein, demonstrated an extremely simple but extraordinary effective strategy to boost PEC water splitting in a three-dimensional (3D) network structure (Ni foam, i.e., NF)-supported ZnO nanowire (NW)/CdS nanoparticle (NP) (NF/ZnO/CdS) photoelectrode. On the one hand, the establishment and optimization of a heteroband junction between ZnO NWs and CdS NPs substantially reduce the solar energy loss and increase the photocarrier utilization rate at the interface of two phases. On the other hand, the solution flow rotation in the unique macroporous 3D network structure gives rise to obvious piezoelectric (PE) polarization of ZnO located on the skeleton of Ni foam, which can dynamically enforce directional charge transfer. This real-time self-built PE polarization, assisted by the heteroband junction, enables the NF/ZnO/CdS photoanode system to obtain an improved photocurrent density by 12.2-fold compared with pure ZnO (at 1.23 V vs RHE). This work sheds light on an ingenious design strategy for fabricating photoelectrodes that combines a simplified structure and an effectively enhanced water oxidation performance.