Facile synthesis of multi-shelled ZnS-CdS cages with enhanced photoelectrochemical performance for solar energy conversion

Abstract

Constructing heterojunctions and designing advanced structures are effective approaches to enhancing the photoelectrochemical performance of semiconductor photocatalysts for solar energy conversion. Here, we have developed a sequential chemical etching, sulfidation, and cation-exchange strategy for preparing multi-shelled ZnS-CdS rhombic dodecahedral cages (RDCs) with tunable compositions and shell numbers from 1 to 5. Yolk-shelled Zn-based zeolitic imidazolate (ZIF-8) RDCs are first synthesized by chemical etching of ZIF-8 rhombic dodecahedrons. Sulfidation of the yolk-shelled ZIF-8 RDCs leads to the formation of multi-shelled ZnS RDCs, which are further converted into multi-shelled ZnS-CdS RDCs via a cation-exchange reaction. The composition of the multi-shelled ZnS-CdS RDCs can be tuned by varying the cation-exchange reaction time, and the shell number can be adjusted by changing the size of ZIF-8 precursors. Because of the heterojunction formed and the unique hollow structure, these triple-shelled ZnS-CdS RDCs with optimized composition show enhanced photoelectrochemical performance for solar water splitting.