ZIF-8 derived hierarchical ZnO@ZnFe2O4 hollow polyhedrons anchored with CdS for efficient photocatalytic CO2 reduction

Abstract

Converting CO2 into chemical energy by efficient photocatalysts is a promising strategy to meet the increasing energy demand and decrease greenhouse gases. In this work, hierarchical ZnO@ZnFe2O4 hollow polyhedrons decorated with CdS quantum dots were designed and prepared to improve photocatalytic CO2 reduction performance. The facile strategy for the synthesis of hierarchical ZnO@ZnFe2O4 hollow polyhedrons involves the synthesis of ZnO hollow polyhedrons derived from the thermal decomposition of 2-Methylimidazole zinc salt (ZIF-8) precursor and in situ generating Zn-Fe layer double hydroxide nanosheets on the surface of ZnO hollow polyhedrons and subsequent thermal treatment. More importantly, the in situ formation of ZnFe2O4 nanosheets can form strong interaction between ZnO hollow polyhedrons and ZnFe2O4 nanosheets. The hierarchical hollow polyhedral structure of the ZnO@ZnFe2O4 sample possesses more preferable active sites to promote CO2 adsorption and reduction process. The prepared hierarchical ZnO@ZnFe2O4 hollow polyhedron sample shows a significantly enhanced performance for photocatalytic CO2 reduction compared with single-component catalysts (ZnO, ZnFe2O4, and CdS) with a CO evolution rate of 95.84 μmol g−1h−1. The decoration of CdS quantum dots makes the ternary heterostructure hybrid form multichannel charge transfer path, which further accelerate charge separation and enhance electrons utilization, resulting in a significant improvement of photocatalytic activity. Noticeably, the CO evolution rate reaches 197.66 μmol g−1h−1, 3 and 2 times higher than that of the bare ZnO and binary ZnO@ZnFe2O4 hollow polyhedrons, respectively. This work gives a promising direction to prepare high-active photocatalysts for solar fuel production.