Electrochemical deposition of p-type β-Ni(OH)2 nanosheets onto CdS nanorod array photoanode for enhanced photoelectrochemical water splitting

In this study, a novel three-dimensional (3D) CdS@Ni(OH)2 nanorod array (NRA) photoanode with a type-II band alignment and a p-n junction has been designed and constructed via a simple electrochemical deposition of hierarchical β-Ni(OH)2 nanosheets onto the surfaces of the CdS NRAs. The 3D CdS@Ni(OH)2 NRA photoanode fabricated under the optimal deposition current exhibits remarkably improved photoelectrochemical water splitting performance, and obtains a photocurrent density of up to 1.1 mA/cm2, 5-fold that of the pure CdS NRA photoanode. Most importantly, the solar-to-hydrogen conversion efficiency of the 3D CdS@Ni(OH)2 NRA photoanode is 3.3-fold higher than that of the pure CdS NRA photoanode at 0.67 V vs. RHE. The electrochemical and photoluminescence emission measurements confirm that the enhanced PEC water splitting capability of the prepared 3D CdS@Ni(OH)2 NRA photoanode is attributed to the efficient charge separation, which is achieved by the synergistic action of the type-II energy alignment and the p-n junction.