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

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.