Sn4+ self-doped hollow cubic SnS as an efficient visible-light photocatalyst for Cr(vi) reduction and detoxification of cyanide

Abstract

Sn⁴⁺ self-doped hollow SnS microcubes are controllably designed by a simple template-assisted synthesis followed by reduction under low temperature. The in situ self-doping enhances the interaction between SnS₂ and SnS. The 3D hollow structures of the photocatalyst improve the light efficiency significantly due to effective multiple reflections in the cave. Therefore, this novel material shows a remarkable reduction performance for Cr(VI) and detoxification of cyanide under visible light irradiation. The concentration of Cr(VI) decreases sharply with the irradiation time, and 99.6% of Cr(VI) is degraded within 50 min. Meanwhile, the chromium ions can be adsorbed completely. Moreover, the removal rate for cyanide is as high as 97.2%. Combined with the analysis of in situ ATR-FTIR spectroscopy technology, the photocatalytic reduction mechanism of Cr(VI) is confirmed as a proton coupled electron transfer process. The improved photocatalytic activity of the Sn⁴⁺ self-doped SnS can be attributed to the enhanced photoabsorption properties and effective separation of photoinduced charge carriers. This general strategy provides a novel route for the synthesis of hollow cubic structural materials, which can be used for photocatalysis, energy storage and wastewater purification applications.