Hollow anisotropic semiconductor nanoprisms with highly crystalline frameworks for high-efficiency photoelectrochemical water splitting

Construction of hollow anisotropic semiconductor nanostructures that possess excellent crystallinity, a flexibly tunable structure/morphology and aqueous dispersity is of special interest for many promising applications such as photoelectrochemical (PEC) water splitting, but has long been hindered by great synthetic challenges. Here we report a powerful and widely applicable approach to fulfill this vision based on cation exchange-induced oxidative etching. Aqueous cation exchange is utilized to chemically convert the shells growing around the shape-controlled Ag templates (such as 2D Ag triangle nanoprisms) into desired semiconductor components (MS, M = Cd and Zn). Remarkably, we found that the soft base ligand used to initiate the cation exchange process can simultaneously induce oxidative etching of the Ag domain forming anisotropic Ag@MS core–shell hybrid nanocrystals, Ag@MS partially hollow hybrid nanocrystals with a controlled degree of hollowness, and hollow MS nanocrystals, depending on the strength of oxidative etching. The resulting core–shell or hollow nanoprisms all exhibit well-defined geometry and crystallinity/interface properties, and this is presumed to be the major reason for their highly efficient performance as the photoanode materials for PEC hydrogen generation.