Photocatalytic performance of tetragonal and cubic β-In2S3 for the water splitting under visible light irradiation

Tetragonal (T-In 2 S 3 ) and cubic (C-In 2 S 3 ) β-In 2 S 3 were synthesized by hydrothermal method. The obtained products were characterized by X-ray diffraction (XRD), diffuse reflectance spectra (DRS), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) technologies. Their photocatalytic activity for hydrogen evolution from water under visible light irradiation ( λ > 400 nm) was evaluated. It was revealed that the photocatalytic activity of β-In 2 S 3 was strongly affected by the arrangement characteristic of the indium vacancies. The vacancy ordered T-In 2 S 3 showed no activity for hydrogen production, while the vacancy disordered C-In 2 S 3 exhibited stable activity. For C-In 2 S 3 sample, further studies indicated that the photoactivity strongly depended on the nature and the amount of noble metal cocatalyst. The optimum loading value of Pt cocatalyst was found to be 2 wt.%. With this loading amount as a reference value, the hydrogen production rate of noble-metal-loaded C-In 2 S 3 decreased in the order Pd > Pt > Ru > Au/C-In 2 S 3 .