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

Abstract

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@CoS_x , CdS@MnS_x , CdS@NiS_x , CdS@ZnS_x , CuS@CdS, and more complexed CdS@ZnS_x @CoS_x . The obtained strawberry-like CdS@CoS_x 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/CoS_x composites (0.57 mmol h^-1 ), and 5 %wt Pt-loaded CdS photocatalysts (1.84 mmol h^-1 ).

Keywords: core-shell structures; metal sulfides; sequential chemistry; visible-light photocatalysts; water splitting.