Non-precious Metal Catalysts For Photocatalytic Reduction Of CO₂

The efficient utilization of solar energy for conversion of CO₂ is one of the effective strategies to solve the current energy crisis and environmental problems.The heterogeneous photoreduction of CO₂ system has attracted much interest because of its unique advantages such as mild conditions,environmental friendliness and recyclability.However,due to the low conversion efficiency,poor selectivity,and unclear mechanisms,the development of efficient catalysts for reduction of CO₂ is in great demand.In this paper,non-precious metal catalysts were prepared and their performances in heterogeneous photocatalytic reduction of CO₂ system including electron conduction properties,the synergistic effect between metals and the morphology of catalysts were studied.?1?We synthesized a series of Ni_1-xCo_xWO₄?x=0?1?catalysts by chemical co-deposition method.Among the prepared materials,Ni_0.85Co_0.15WO₄ exhibits superior catalytic performance for photocatalytic reduction of CO₂ to CO with[Ru?bpy?₃]Cl₂·6H₂O as the photosensitizer.The productivity and selectivity of CO are 14.33 mmol·g^-1·h^-1 and 86.4%,respectively.The experimental results demonstrate that superiority of electron conductivity of metal tungstates and the high activity of Co active sites facilitate the separation and transfer of photo-induced charges and lead to the excellent performance of photcatalytic reduction of CO₂ to CO.?2?Cobalt-doped Ni-MOF was synthesized via solvolthermal method and used as catalyst for photocatalytic reduction of CO₂ to CO.The results show that the revolution rate and selectivity of CO are 16.84 mmol·g^-1·h^-1 and 74.2%with NiCo-BTC-0.5(Ni_2.5Co_0.5?BTC?₂?12H₂O)as the catalyst,which is better than non-doped Ni-BTC.The superior photocatalytic performance of NiCo-BTC towards CO₂ reduction results from the synergistic effect between Ni and Co.?3?The MOF derivative Co₃O₄-NC@SiO₂ with the core-shell structure is prepared via pyrolysis method.The as-prepared Co₃O₄-NC@SiO₂ exhibits excellent activity and stability with a revolution rate of 15.01 mmol·g^-1·h^-1,for the photocatalytic reduction of CO₂ to CO which is superior to ZIF-67,Co₃O₄-NC,Co₃O₄-NP,and CH-Co₃O₄.Further analysis of experimental results demonstrate that the MOF derivative combines the structural and functional advantages of the active Co with graphitized carbon in the three-dimensional core-shell architecture,which is beneficial to the absorption of CO₂,exposure of more active sites,and migration as well as separation of photogenerated charge carriers.