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

Tetragonal (T-In2S3) and cubic (C-In2S3) β-In2S3 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-In2S3 was strongly affected by the arrangement characteristic of the indium vacancies. The vacancy ordered T-In2S3 showed no activity for hydrogen production, while the vacancy disordered C-In2S3 exhibited stable activity. For C-In2S3 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-In2S3 decreased in the order Pd > Pt > Ru > Au/C-In2S3.