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

Abstract

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.