Sequential Chemistry Toward Core-Shell Structured Metal Sulfides as Stable and Highly Efficient Visible-Light Photocatalysts

A universal sequential synthesis strategy in aqueous solution is presented for highly uniform core-shell structured photocatalysts, which consist of a metal sulfide light absorber core and a metal sulfide co-catalyst shell. We show that the sequential chemistry can drive the formation of unique core-shell structures controlled by the constant of solubility product of metal sulfides. A variety of metal sulfide core-shell structures have been demonstrated, including CdS@CoSx, CdS@MnSx, CdS@NiSx, CdS@ZnSx, CuS@CdS, and more complexed CdS@ZnSx@CoSx. The obtained strawberry-like CdS@CoSx core-shell structures exhibit a high photocatalytic H-2 production activity of 3.92 mmol h(-1) and an impressive apparent quantum efficiency of 67.3% at 420 nm, which is much better than that of pure CdS nanoballs (0.28 mmol h(-1)), CdS/CoSx composites (0.57 mmol h(-1)), and 5%wt Pt-loaded CdS photocatalysts (1.84 mmol h(-1)).