Mesoporous yolk–shell SnS2–TiO2 visible photocatalysts with enhanced activity and durability in Cr(vi) reduction

Abstract

A novel mesoporous yolk–shell SnS₂–TiO₂ visible photocatalyst (ST-is) was synthesized by in situ doping TiO₂ with SnO₂ through solvothermal alcoholysis, followed by sulfurization under hydrothermal conditions. The ST-is displayed higher activity in photocatalytic reduction of Cr(VI) owing to the strong photosensitizing effect of SnS₂ in uniform nanoparticles and the enhanced light harvesting via multiple reflections in yolk–shell chambers. Meanwhile, the strong SnS₂–TiO₂ interaction could generate more heterojunctions which facilitated photoelectron transfer from SnS₂ to TiO₂, leading to the enhanced activity by inhibiting photoelectron–hole recombination. Moreover, the ST-is displayed strong durability owing to the strong SnS₂–TiO₂ interaction and the encapsulation of SnS₂ nanoparticles in the yolk–shell chamber, which could inhibit SnS₂ leaching. Furthermore, because of the electronegative surface and high surface area, the ST-is could thoroughly purify wastewater by completely adsorbing Cr³⁺ resulting from Cr(VI) reduction. In addition, the presence of photocatalytic degradation of organic compounds promoted Cr(VI) reduction owing to inhibition of photoelectron–hole recombination by consuming holes.