Synthesis of stannite Cu2CoSnS4 and its use as photocatalyst for degradation of pollutants

Abstract

We report the synthesis of p-type stannite Cu2CoSnS4 (CCTS) powder by direct fusion, and its use as a photocatalyst for the degradation of methylene blue (MB) under solar irradiation. Structural analysis by X-ray diffraction and Raman spectroscopy revealed that the prepared powder is polycrystalline and has preferential orientation along the (112) plane, characteristic of the stannite phase. Scanning electron microscopy (SEM) images show agglomerated nanoparticles. Compositional analysis by energy dispersive spectroscopy shows that the composition of the prepared CCTS powder approaches the theoretical 2:1:1:4 stoichiometry. The oxidation state of the constituent elements in CCTS powder were investigated by X-ray photoelectron microscopy (XPS), which reveals that the valence states of the constituent elements present in the CCTS sample are: Cu+, Co2+, Sn4+and S2−. Optical analysis through diffusion reflectance and photoluminescence (PL) spectroscopy were used to estimate the bandgap, which was found to be about 1.4 eV. Upon visible light illumination, CCTS powder exhibits an excellent photocatalytic performance. The apparent reaction rate constant k found to be k = 13.10−3 min−1, which suggests that the p-type stannite CCTS powder would be a promising candidate of photocatalyst for the degradation of MB in aqueous solution.