Synergistic effects of 2D/2D ZnV₂O₆/RGO nanosheets heterojunction for stable and high performance photo-induced CO₂ reduction to solar fuels

Highly photo-stable and efficient 2D/2D zinc vanadium oxide-reduced graphene oxide (ZnV₂O₆/RGO) nanosheets heterojunction was fabricated by the one-pot solvothermal method. The structures and properties of the catalysts were analyzed by XRD, FE-SEM, EDX, TEM, BET, UV–vis, Raman and PL spectroscopy. The 2D/2D ZnV₂O₆/RGO catalyst shows excellent performance towards CO₂ photo-reduction with H₂O to CH₃OH, CH₃COOH and HCOOH under visible light. The yield of the main product CH₃OH of 5154 μmol g-cat⁻¹, obtained over ZnV₂O₆/4%RGO, was 1.6 times the amount of CH₃OH produced over the pure ZnV₂O₆ (3254 μmol g-cat⁻¹) and a 5.5-fold higher than that of the ZnO/V₂O₅ composite (945 μmol g-cat⁻¹). In addition, CH₃OH selectivity of 39.96% achieved over the ZnO/V₂O₅ composite increased to 68.89% in ZnV₂O₆/4%RGO. The continuous and selective production of CH₃OH was detected over the entire irradiation time in ZnV₂O₆ and ZnV₂O₆/4%RGO samples, whereas the yield of products gradually decreased in ZnO/V₂O₅. The significant improvement in photo-activity over 2D ZnV₂O₆ structure was due to the hierarchical structure with enhanced charges separation. A combined 2D/2D ZnV₂O₆/RGO nanosheets prevailed as a promising strategy to ameliorate the photocatalytic performance of ZnV₂O₆ nanosheets due to efficient trapping and transport of electrons by RGO. The synergistic effects in ZnV₂O₆/RGO 2D/2D nanosheets exhibited excellent photocatalytic stability, which prevailed even after 32 h of operation time for selective and continuous CH₃OH production. A proposed photo-induced reaction mechanism, corroborated with the experimental data, was also deliberated.