Effect of hydrothermal reaction time on the photoelectrochemical performance of nanostructured WO3 photoanode

Abstract

Hydrogen evolution by photoelectrochemical (PEC) water splitting with the use of semiconductor photocatalysts is a promising method for alternative energy production. Tungsten trioxide (WO3) has been investigated for its PEC performance because of its promising advantages: availability, cost-effectiveness, and proper band gap energy. However, the PEC performance is strongly influenced by morphology, which can be tailored by adjusting the synthesis condition. In this paper, we report the investigation on the effect of hydrothermal time on phase formation, morphology, optical properties, and PEC performance of WO3 films. Nanostructured WO3 films were grown on fluorine-doped tin oxide (FTO) substrates by hydrothermal method at 160 ℃. The morphology and optical properties of the WO3 layer were modified by varying the hydrothermal time of 2, 4, and 6 h. Then, a heat treatment at 500 ℃ for 2 h was carried out for all samples. The crystal structure, morphology, and optical properties of WO3/FTO were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV–visible spectroscopy, respectively. The PEC performance of the WO3 photoanode was investigated by a potentiostat with a three-electrode system. The results showed that short hydrothermal time provided a better WO3 film for PEC water splitting.