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

Abstract

This work demonstrates hierarchical WO 3 nanosheet/CdS nanorod (WO 3 -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, WO 3 -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 WO 3 -NS arrays (0.45 mA cm −2 ) and 3 times that of CdS-NR arrays (1.85 mA cm −2 ). In this hybrid WO 3 -NS/CdS-NR arrays photoanode, the favorable heterojunction between WO 3 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 WO 3 -NS/CdS-NR arrays. Finally, the coating of an ultrathin layer of amorphous TiO 2 also enhances the photostability of WO 3 -NS/CdS-NR arrays. Hierarchical WO 3 nanosheet/CdS nanorod arrays showed improved PEC performance than pristine WO 3 nanosheet and CdS nanorod arrays due to the synergistic effect of different constituents in the novel hierarchical structure. The coating of amorphous TiO 2 layer further increases the photostability. • Novel hierarchical WO 3 -Nanosheet/CdS-Nanorod arrays were reported. • Hierarchical structure plays a significant role in photocurrent enhancement. • An ultrathin layer of TiO 2 layer enhances photostability of WO 3 -Nanosheet/CdS-Nanorod arrays.