Amorphous TiO2 coated hierarchical WO3 Nanosheet/CdS Nanorod arrays for improved photoelectrochemical performance

This work demonstrates hierarchical WO3 nanosheet/CdS nanorod (WO3-NS/CdS-NR) arrays as a type-II heterojunction photoanode for improved photoelectrochemical (PEC) water splitting. Due to the synergistic effect of different constituents in the novel hierarchical structure, WO3-NS/CdS-NR arrays as a photoanode yield a photocurrent density of 5.4 mA cm(-2) at 0.8 V versus reversible hydrogen electrode for sulfite oxidation. This is 12 times that of WO3-NS arrays (0.45 mA cm(-2)) and 3 times that of CdS-NR arrays (1.85 mA cm(-2)). In this hybrid WO3-NS/CdS-NR arrays photoanode, the favorable heterojunction between WO3 and CdS enhances the charge separation efficiency and widens the light absorption spectrum. Furthermore, the optimization of the loading amount and size of CdS-NRs allows for a larger specific surface area as well as more effective light scattering, which further improves the PEC performance of WO3-NS/CdS-NR arrays. Finally, the coating of an ultrathin layer of amorphous TiO2 also enhances the photostability of WO3-NS/CdS-NR arrays.