Synthesis and characterization of WO3 photoanodes for efficient photoelectrochemical water splitting

Choosing suitable photoanode materials is the most critical aspect for photoelectrochemical (PEC) water splitting. The low efficiency of PEC water splitting photoanodes restricts their widespread application for large-scale H-2 production. Herein, we prepared WO3 photoanodes with controllable structures via hydrothermal-electrophoretic deposition and seed-mediated hydrothermal synthesis, achieving ex situ assembly and in situ growth on FTO glass substrates. Under simulated sunlight irradiation, the photoelectric current density of the WO3 photoanode prepared by in situ hydrothermal synthesis exceeds 1.0 mA/cm(2) (at 1.23 V vs. RHE), significantly higher than that of the WO3 photoanode prepared by ex situ assembly (which is less than 0.3 mA/cm(2) at 1.23 V vs. RHE). By contrast, the in situ preparation of the WO3 photoanode using tungsten powder and H2O2 as raw materials exhibits the enhanced photocurrent density of 1.27 mA/cm(2) at 1.23 V vs. RHE. The excellent PEC performance of the resulting sample could be attributed to the ordered charge transport channels from the two-dimensional (2D) nanoplates structure, the enhanced electron-hole pairs separation from the superior crystallinity of WO3 and the strong binding between the WO3 nanoplates and the FTO substrate. Additionally, the effect of calcination temperature on the PEC performance of the prepared WO3 was further investigated. This work provides a way for the synthesis of environmentally friendly and cost-effective photoanodes for efficient photoelectrochemical water splitting.