Study On Photocatalytic Reduction Of Co₂ By Transition Metal Complexes

Photocatalytic reduction of CO₂ is a hot research nowadays.Scientists imitate the natural photosynthesis,using metal complexes,semiconductor materials transfer photoelectron to the CO₂ in the presence of catalysts,and it is reduced to organic fuel.A photocatalytic reduction of CO₂ system usually consists of photosensitizer,catalyst,sacrificial reductant etc..However,it is still a challenge to set up an efficient,stable and low cost photocatalytic reduction CO₂ system,while ensuring the high CO₂ conversion efficiency,but also take into account the product selectivity.In this paper,a relatively simple and efficient photocatalytic reduction system was established,CO₂ was reduced to CO under the irradiation of visible light,and some meaningful results were obtained.1.We modified [Ru（bpy）₃]²⁺ with β-cyclodextrin to obtain the supramolecular complex [CD-Ru（bpy）₃]²⁺ as the photosensitizer,using common metal salts（FeCl₃,CoCl₂·6H₂O,NiCl₂）coordinated with TEOA to form [M（TEOA）₂]Cl_x（M represents metal,x = 2,3）complexes as catalysts.We also used BIH and TEOA as co-sacrificial agents.The synthesized complexes were characterized and their spectra and electrochemical properties were studied.Respectively,[Ru（bpy）₃]²⁺ and [CD-Ru（bpy）₃]²⁺ as a photosensitizer of photocatalytic reduction system,the photocatalytic activity of CO₂ reduction was compared,the latter was much higher than that of the former,and Ni was the center of the catalyst Metal catalysis effect is slightly higher with the other two metals,the TON-（CO） of the system to up to 433 during 10 h of irradiation.2.We used easily prepared metal phthalocyanine as a catalyst.On the basis of cobalt phthalocyanine and tetramethyl cobalt phthalocyanine,two kinds of metal phthalocyanine complexes were obtained by coordination of diethyl phosphite and central metal in the axial direction of the molecule.The complexes were characterized and their optical properties were studied.In the photocatalytic system,using [Ru（bpy）₃]²⁺ as the photosensitizer,It founds that the cobalt-substituted phthalocyanine was better than that of the unsubstituted cobalt phthalocyanine,and the metal phthalocyanine with axial coordination was better than that of the non-axial coordination metal phthalocyanine,during 10h of irradiation,the TON-（CO） of the system reached 23.65.