Construction of ZnO@CDs@Co3O4 sandwich heterostructure with multi-interfacial electron-transfer toward enhanced photocatalytic CO2 reduction

Photocatalytic conversion of CO2 into small-molecule chemical feedstocks can meet the growing demand for energy and alleviate the global warming. Herein, a p-n ZnO@CDs@Co3O4 heterojunction with sandwich structure was constructed by calcination method of self-assembled ZIF-8@CDs@ZIF-67. The ZnO@CDs@Co3O4 with well-defined interfacial structure exhibited the significantly enhanced photocatalytic CO2 reduction activity, and the optimal catalyst indicated the (CO + CH4) evolution rate of 214.53 µmol g−1 h−1 under simulated solar light, which was superior to ZnO, Co3O4 and binary ZnO@Co3O4. The internal cavity, exposed active sites, multiple interfaces and constructed p-n heterojunction can facilitate the light harvesting and photoexcited electron transfer. Besides, after introduction of CDs placed in the middle layer between ZnO and Co3O4, CDs with excellent photoelectric property further promoted charge separation and migration. This work represents an appealing strategy to construct well-defined photocatalysts for boosting CO2 photoreduction.