Template-free synthesis of Mn2+ doped hierarchical CuS yolk–shell microspheres for photocatalytic reduction of Cr(vi)

Abstract

Yolk–shell structures have been widely used in catalysis and energy storage in recent years because they improve the efficiency of charge utilization by enhancing light scattering and creating more active sites in the hollow space. Here we synthesized Mn²⁺ doped hierarchical CuS yolk–shell microspheres by a one-step solvothermal method. The influences of reaction time on the structure and morphology during the formation process of hierarchical CuS yolk–shell microspheres are studied in order to explore their formation mechanism. And a rational phenomenological approach is proposed to describe the nucleation, Ostwald ripening and self-assembly processes associated with the formation of hierarchical yolk–shell structures. Compared with another CuS microsphere sample without the assistance of acetate, Mn²⁺ doped CuS yolk–shell microspheres showed better Cr(VI) photoreduction performance, which can be ascribed to the existence of yolk–shell hierarchical structures and Mn²⁺ doping. Finally, a photocatalytic reaction mechanism has been proposed.