Metal-Organic Frameworks?MOFs? For Photo/Electrocatalytic Reduction Of CO₂

The burning of a great quantity of fossil fuels has broken the carbonaceous balance in nature and caused a series of energy and environmental problems.By mimicking the green plants,artificial photosynthesis can utilize renewable energy sources such as solar energy,and convert the carbon dioxide into fuels and value-added chemicals.At present,the research efforts of artificial photosynthesis has been focusing on the exploitation of highly active and stable catalysts.This thesis concentrates on the photo/electroreduction of carbon dioxide with metal-organic frameworks?MOFs?and the other nanocatalysts.?1?Zn-TCPP?Fe?MOF nanosheets were fabricated by a surfactant induced method and loaded on canbon paper as a composite electrode for electroreduction of carbon dioxide in a 0.5M aqurous solution of KHCO₃.The products were carbon monoxide and hydrogen,and the faradic efficience of carbon monoxide of 82.64%at-0.7 V vs Reversible Hydrogen Electrode?RHE?was achieved;?2?ZIF-67,a typical MOFs,with three different morphologies were fabricated by a solution indeced method,and were used as cocatalyst for photocatalytic reduction of carbon dioxide.The experimental results reveal that the leaf-like ZIF-67₃ with a sheet morphology exhibited higher activity than the other two samples,which is due to the large number of active catalytic site within the nanosheet structure of ZIF-67₃,and its highest carbon dioxide adsorption capability;?3?The Mn₃O₄/Co_x Mn_3-x-x O₄ nanocubes were prepared via a galvanic replacement reactions between metel oxide,as a cocatalyst in a photocatalytic system,the Mn₃O₄/Co_x Mn_3-xO₄nanocubes can efficiently catalyze carbon dioxide into carbon monoxide with a high TON value of 581 in 3 hours,which is due to the highly active Co_x Mn_3-x-x O₄ species only distributed on the surface of the nanocubes.This study has a directive significance to the design of high TON value catalysts,especially for precious metal catalysts.