Indirect Z-Scheme Assembly of 2D ZnV2O6/RGO/g-C3N4 Nanosheets with RGO/pCN as Solid-State Electron Mediators toward Visible-Light-Enhanced CO2 Reduction

Indirect Z-scheme assembly of graphene-bridged 2D ZnV2O6/pCN nanosheets composite has been fabricated by one-step solvothermal process and tested for photoinduced CO2 conversion under visible-light irradiations. The highest CH3OH production of 3488 μmol g-cat–1 was obtained over ZnV2O6/RGO/g-C3N4 composite, 1.02 and 1.25 times higher comparing to ZnV2O6/RGO and ZnV2O6/g-C3N4 samples, respectively. This enhanced efficiency can be ascribed to well-designed ternary heterojunction with hierarchical structure and efficient charges separation by RGO. More importantly, CH3OH yield was further improved by introducing RGO/pCN as an electron sink, which led to a 1.07 times higher yield than using only RGO. This reveals that ternary 2D ZnV2O6/RGO/pCN nanostructure has higher visible-light absorption, improved charge separation, and enhanced photocatalytic efficiency due to RGO/pCN as multiple mediators. The stability of composite catalyst also prevailed for 32 h for continuous CH3OH production. Therefore, structured Z-scheme composite with multiple electron mediators enables efficient CO2 conversion under visible-light irradiation.