Construction Of Composite System For Light-driven Enzyme-catalyzed Carbon Dioxide Reduction

Excessive carbon dioxide emissions will directly lead to cyclical climate changes and environmental pollution around the world.Therefore,the research of carbon dioxide reduction has attracted wide attention from scientists.Biocatalytic carbon dioxide reduction has the advantages of mild reaction conditions and high product specificity.It has been widely studied and concerned.Formate dehydrogenase is often used to catalyze the reduction of carbon dioxide to the chemical formic acid,but formate dehydrogenase requires continuous environmental protection Supply the expensive cofactor NADH.Therefore,the use of solar energy as a sustainable energy regeneration NADH-driven enzyme to catalyze carbon dioxide reduction reaction is an efficient,sustainable,green and clean strategy.In this study,we designed a light-driven enzyme-catalyzed carbon dioxide reduction composite system that simulates photosynthesis in nature.The light-trapping material absorbs sunlight and converts it into chemical energy to provide enzyme-catalyzed reactions.The composite system includes the photocatalytic material TPE-C3N4,the electron mediator rhodium complex,NAD⁺and MOF protected formate dehydrogenase,which can realize the reduction of carbon dioxide to formic acid under the light drive.TPE-C₃N₄is a photocatalytic material with simple synthesis method,stable physical and chemical properties,good biocompatibility and high photocatalytic ability.It can generate electrons under light excitation and transfer the electrons to the rhodium complex fixed on the surface Catalyze the regeneration of NADH.The rhodium complex immobilized on the surface not only reduces the mutual adverse effects of free rhodium complex and formate dehydrogenase,but also improves the electron transfer efficiency and NADH regeneration efficiency.MOF protection can reduce the effect of superoxide produced by photocatalytic materials on enzyme activity,so as to stabilize the use of NADH to reduce carbon dioxide to formic acid.In the entire hybrid system,the electrons are driven by light from C₃N₄to the NAD+through the rhodium complex and reduced to NADH,then NADH transfers the electrons to formate dehydrogenase,and finally carbon dioxide is reduced to formate by formate dehydrogenase.The continuous regeneration of NADH driven by light catalyzes the continuous operation of enzyme-catalyzed carbon dioxide reduction.Finally,this light-driven enzyme-catalyzed carbon dioxide reduction composite system can stably reduce carbon dioxide and accumulate formic acid under light.After 9 hours of reaction,the concentration of formic acid in the solution is 16.76 m M,which is higher than that of the control group（free 7TFDH and TPE-C₃N₄,formic acid concentration 5.16 m M）3.24 times higher.