Photocatalytic Reduction Of CO₂ By Cobalt-Based Porphyrin Complexes And Composite Materials

The heavy reliance on fossil fuels for the production of energy has increased atmospheric CO₂ emissions,which is considered to be an important factor in anthropogenic climate change.Photocatalytic reduction of CO₂ to produce high value-added fuels such as CO,methanol,methane,and aliphatic hydrocarbons offers a package solution to address both the increasing energy requirements and climate change,and therefore attracted wide attention.In this thesis,cobalt-based porphyrin complexes and Co₃O₄/SBA-15 composites were synthesized and characterized.Their catalytic properties for photocatalytic reduction of carbon dioxide to carbon monoxide were studied.The specific research contents and results are as follows:1.CoTIPPcomplexwassynthesizedbyreacting5,10,15,20-tetrakis?4-?imidazol-1-yl?phenyl?porphyrin?TIPP?with cobalt?II?salt.CoTIPP-DBXL and CoTIPP-TBMB polymer are obtained according to same procedure except that TIPP derivatives were used as ligands that are synthesized by?,?'-Dibromo-p-xylene and 1,2,4,5-tetrakis?bromomethyl?benzene introduced to TIPP.The structures of complexes are charactweized by infrared,mass spectrometry and elemental analysis.Three complexes were used as catalysts to perform their photocatalytic properties of CO₂ reduction in the presence of photosensitizer and electron donor,as well as various their contents with different solvents.A visible-light catalytic rate of up to 18614?mol h^-1 g^-1 for CoTIPP-DBXL polymer was achieved under optimal condition.2.The Co₃O₄/SBA-15 composites was prepared and characterized by XRD,TEM,SEM.Co₃O₄/SBA-15 hybrid and Co₃O₄ nanoparticles were used as catalysts to study photocatalytic CO₂ transformation to CO.The gained results showed that Co₃O₄/SBA-15 hybrid exhibits high catalytic rates with up to 26316?mol g^-1?irradiation for 2.5 hours?and the selectivity is 76.5%in mixed aqueous solutions containing a Ru-based photosensitizer under visible-light irradiation.