Crystallite, optical and photocatalytic properties of visible-light-driven ZnIn₂S₄ photocatalysts synthesized via a surfactant-assisted hydrothermal method

A series of ZnIn₂S₄ photocatalysts were synthesized via a surfactant-assisted hydrothermal method. The products were characterized with X-ray diffraction (XRD), UV-vis-near-IR diffuse reflectance spectra (UV-vis), photoluminescence spectra (PL) and field emission scanning electron microscope (FESEM). The results indicated that the CTAB-assisted ZnIn₂S₄ product had a wider band gap than the other three ZnIn₂S₄ products (CPBr-assisted, SDS-assisted and no-surfactant-assisted ZnIn₂S₄). The surfactant (especially CTAB) addition would greatly affect the crystal structure (i.e. d(0 0 6) along the c-axis) of ZnIn₂S₄. The photocatalytic activities of the as-prepared samples were evaluated by photocatalytic hydrogen production from water under visible light irradiation. The CTAB-assisted ZnIn₂S₄ product, with quantum yield (420 nm) determined to be 11.9%, had a much higher photocatalytic activity than the other three ZnIn₂S₄ products in our photocatalytic system. The energy conversion efficiency in the whole visible light region was determined to be 3.1% for the CTAB-assisted ZnIn₂S₄ photocatalyst.