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 H2 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 ).