Fabrication of reduced graphene oxide (rGO) mediated ZnV2O6 nanosheets for enhancing photocatalytic CO2 reduction under UV and solar light irradiation.

Abstract

Well-designed reduced graphene oxide (rGO) coupled with zinc vanadate (ZnV2O6) to construct a binary heterojunction nanocomposite for boosting photocatalytic reduction of CO2 has been investigated. Samples were synthesized using a single-step solvothermal process and examined in a fixed bed photoreactor under UV and solar light. The 4%rGO coated over ZnV2O6 nanocomposite has presented excellent activity in converting CO2 to CO, H2 and CH4 under solar light irradiation. The yield of main product CO, is 3707.5 μmol g-cat−1 over 4%rGO/ZnV2O6, which is 1.53 times the yield of CO obtained over the ZnV2O6 nanosheets (2426.2 μmol g-cat−1). Furthermore, the CO selectivity of 87% obtained on ZnV2O6 increased to 90% in 4%rGO/ZnV2O6 nanocomposite. The enhancement was attributed to synergistic effect of the binary heterojunction with boosted charge separation by rGO under solar light. Conversely, a two-fold decrease in productivity was observed when using UV light compared to solar light, due to higher absorption of solar light. Thus, rGO coupled with ZnV2O6 exhibited excellent stability without deactivation under solar light and can be a potential structured material for other energy applications. A reaction mechanism is also presented to describe the reaction pathways.