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

A novel mesoporous yolk-shell SnS(2)-TiO(2) visible photocatalyst (ST-is) was synthesized by in situ doping TiO(2) with SnO(2) 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 SnS(2) in uniform nanoparticles and the enhanced light harvesting via multiple reflections in yolk-shell chambers. Meanwhile, the strong SnS(2)-TiO(2) interaction could generate more heterojunctions which facilitated photoelectron transfer from SnS(2) to TiO(2), leading to the enhanced activity by inhibiting photoelectron-hole recombination. Moreover, the ST-is displayed strong durability owing to the strong SnS(2)-TiO(2) interaction and the encapsulation of SnS(2) nanoparticles in the yolk-shell chamber, which could inhibit SnS(2) leaching. Furthermore, because of the electronegative surface and high surface area, the ST-is could thoroughly purify wastewater by completely adsorbing Cr(3+) 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.