Nanoscale-based ZnS-GdS shell layer decorated hierarchical ZnO nanorod array photoanode with enhanced photo-electrochemical activity under visible light

We established a nanograined ZnS-GdS shell layer decorated with hierarchical ZnO nanorod (NR) arrays with significantly improved visible light photo-electrochemical performance. The ZnO nanorod surface is decorated with a ZnS-GdS shell layer through the sulfidation. Photoluminescence (PL) spectral study stated that the introduction of a ZnS-GdS shell layer improvises effective charge separation efficiency with the additional influence of surface defect states. The ZnO/ZnS-GdS core-shell NR array shows higher photo-electrochemical performance than the ZnO NR arrays under visible light, with a significant photocurrent density of 2.6 mA/cm². The highest solar to hydrogen conversion efficiency is reached 3.2%, 14 times higher than pristine ZnO nanorod with a bias potential of 0 V versus Ag/AgCl. The results suggest that the ZnS-GdS shell layer enhances the visible light absorption and makes heterostructure, which helps transfer photogenerated charge carriers and reduces the recombination rate to enhance the photo-electrochemical efficiency of ZnO/ZnS-GdS heterostructure.