Bio-inspired Construction And Performance Intensification Of Enzyme-photo Coupling Catalytic System Based On Microcapsular Structure

Enzyme-photo coupling catalytic system,which combined the high activity and specificity of enzyme with the excellent light harvesting capacity of semiconductor photocatalyst,provided a green route for the production of chemicals.However,the combination of enzymatic reaction and photocatalytic reaction led to a complex catalytic system.An efficient enzyme-photo coupling system required the orchestration of different reactions,including the efficient electron transfer from photocatalyst to enzyme and the compatibility between photocatalyst and enzyme.Herein,inspired by the confinement phenomena in natural complex catalytic system,we used microcapsular structure to coordinate enzymatic reaction and photocatalytic reaction for the construction of efficient enzyme-photo coupling catalytic system.First,the microcapsular enzymatic and photocatalytic system was constructed by bioinspired method for optimizing the performance of enzymatic reaction and photocatalytic reaction,respectively.Then,the microcapsular structure was utilized to coordinate enzymatic reaction and photocatalytic reaction for efficient CO₂conversion.The details of this study were summarized as follows:Bioinspired construction and performance intensification of microcapsular enzymatic system:inspired by polyphenol chemistry and biomineralization,we constructed polymer and polymer-inorganic ultrathin hybrid microcapsular enzymatic system,respectively.The as-prepared microcapsules provided benign microenvironment for the encapsulated enzyme,which kept the intrinsic activity and elevated the thermal and pH stability of the enzyme.The performance of the microcapsular enzymatic system was improved by manipulating the composition and wall thickness of the microcapsules.Bioinspired construction and performance intensification of microcapsular photocatalytic system:inspired by biomineralization,we constructed a CdS quantum dots decorated protamine/titania?CdS/PTi?microcapsular photocatalytic system.The strong electronic coupling and favorable band structure between CdS and PTi facilitated the electron transfer from CdS quantum dots to PTi capsule wall for efficient NADH regeneration.The optimum NADH regeneration yield was93.0±3.8%and quantum efficiency was 37.1±4.2%.Bioinspired construction and performance intensification of microcapsular enzyme-photo coupling catalytic system:CdS/PTi microcapsular photocatalyst was coupled with single enzyme?formate dehydrogenase?and multi-enzymes?formate/formaldehyde/alcohol dehydrogenases?for enzyme-photo coupled conversion of CO₂ to formate and methanol.The size-selective capsule wall compartmentalized enzymatic reduction reaction and photocatalytic oxidation reaction,protecting enzymes from deactivation by photo-generated holes.The photo-generated electrons were transferred from the inner surface of the capsule wall to the outer surface of the capsule wall through the heterostructure of CdS and PTi,and then transferred to formate dehydrogenase through NADH for CO₂ conversion.Under continuous visible light illumination,the enzyme-photo coupled catalytic system achieved formate and methanol outputs of 1500?M h^-1 and 99?M h^-1 with single enzyme and multi-enzymes,respectively.Under light-dark cycles,the enzyme-photo coupled catalytic system continuously converted CO₂ into formate with a quantum efficiency of 0.66±0.13%.