Study On Photocatalytic Reduction Of CO _{2 Based On Fe, Mn And Other Inexpensive Transition Metal Complexes}

Developing low-cost, high efficient and stable photocatalysts for photocatalytic reduce CO₂ to valuable product such as CO remains a considerable challenge. Herein,we have gotten rid of the past strategy that people focused on the expensive metals catalysts such as Ru, Re, et al. So we report some abundant transition metal pohtocatalysts: simple Fe, Ni, Mn and Cu complexes, for reduce CO₂ to CO. In this work, some simple and efficient homogeneous photocatalytic reduction system were established with high selectivity（negligible amount of H2 was formed）. To the best of our knowledge, with BNAH（1-benzyl-1,4-dihydronicotinamide） or BIH（1,3-dimethyl-2-phenylbenzimidazoline） as electron donor, using homogeneous catalysts in the visible light and DMF for photodriven reduction of CO₂ to CO is for the first time.We synthesized complexes F1, F2, F3 and F4, using iron salts and TEOA; using pyridine derivatives 2-pyridinethiol as ligand synthesized complexes M1, M2, N1,N2, C1 and C2. The photocatalytic properties, spectral properties and electrochemical properties of these complexes were researched.F1, F2, F3 and F4 show different activities for CO₂ photoreduction, by using them as visible light photocatalysts. All the self-assembly catalysts were higher efficient for CO production compared to the pre prepared catalysts. With F2 as catalyst, the turnover number of CO was 32. In addition, the photocalytic system in which F2 as catalyst added with BNAH or BIH, a TON of 46 or 90 for CO production were obtained, respectively.Using M1, M2, N1, N2, C1 and C2 as photocatalysts, under vis-light irradiation,we noted that the photocatalytic properties of these photocatalysts were similar.The experiments of luminescence quenching showed electron donor of BNAH and BIH are more capable of quenching excited photosensitizer compare to TEOA.