Functional Design Of Biomimetic Metal-organic Hybrid Materials And Photo/Electrocatalytic CO₂ Reduction

In natural photosynthesis,green plants and algae absorb light energy,convert water and CO₂ into organic compound and release oxygen.It is of great significance to synthesize artificial materials and construct artificial systems by simulating natural photosynthesis,absorbing light energy and converting it into chemical energy.Further development of biomimetic catalysts for CO₂ reduction has a profound impact on the achievement of the goal of“carbon peaking＆carbon neutralization”.The precise controllable structural characteristics of metal-organic hybrid materials can realize the construction of biomimetic active sites,and its uniform cavity structure can realize the immobilization of higher density active centers.Its pore structure also can protect the catalytic active centers,meanwhile realize the rapid transport of substrates.In addition,its thermal and chemical stable structure can achieve higher cycling stability.Based on metal-organic hybrid materials,the material is functionally designed to realize the preparation of biomimetic catalysts by utilizing the characteristics of tunable structure,and then applied to photo/electric CO₂ catalytic reduction.The main contents are as follows:1.Biomimetic metalation of MIL-125-NH₂ promotes NADH regeneration and enhanced gas-liquid-solid three-phase enzymatic CO₂ reductionMimicking the natural photosynthesis and the metal center and second coordination environment of enzymes,based on MIL-125-NH₂,the Schiff-base reaction of-NH₂ on organic ligands is used to form iminopyridine units,and the immobilization of Rh complexes is realized by subsequent metallization treatment,which is finally successfully used for NADH regeneration and further coupling formate dehydrogenase achieves efficient conversion of CO₂ to formate.The test characterization proved that the Rh complex was successfully anchored to the secondary coordination structure in MIL-125-NH₂ after Schiff-base reaction,and a stable Rh-C₅N₂Cl structure was formed.In addition,the feasibility of covalent modification and metallation reaction is also indicated by theoretical calculation.Schiff base-functionalized ligands in MIL-125-NH₂act as both a light-harvesting site and an Rh complex immobilization site,thereby facilitating the direct photo-induced electron transfer to the anchored Rh complex for NADH regeneration.Furthermore,the gas-liquid-solid three-phase interface photo-enzyme catalytic system was constructed by immobilizing formate dehydrogenase using a regenerated cellulose membrane with a hydrophilic/hydrophobic structure.Due to the hydrophilic/hydrophobic patterns on the membrane,the integrated photo-enzyme system can utilize the in situ generated NADH for efficient production of formate from CO₂.This work provides ideas for the design of an efficient and recyclable artificial materials-enzyme integrated system.2.Structural design of hydrophobic bismuth-based organometallic halide materials and electrocatalytic CO₂ reduction to formic acidInspired by the secondary coordination structure of metalloenzymes,and based on the work idea of using bipyridine to coordinate an anchor metal,the N-coordinated bismuth-based organometallic halide materials are designed and constructed,which improves the water stability of the materials and realizes efficient CO₂ electrocatalytic reduction.The crystal structure and water stability of the 22bpy-Bi I₃ catalyst were demonstrated by measurements.Moreover,the catalyst prepared by thermal-injection method exhibits the intrinsic hydrophobic property,which can be used to enrich CO₂ in the aqueous phase and theoretically improve the electrocatalytic CO₂ reduction performance.The catalyst exhibits a regular sheet-like structure after electroreduction,and can achieve a faradaic efficiency of 88.0%formate at-1.0 V vs RHE overpotential.And further by plasma treatment,it is shown that the addition of hydrophobicity can indeed achieve greater current density and higher carbon product yield in electrocatalytic CO₂ reduction.This work provides a feasible strategy for developing water-stable organometallic halide materials and opens up the application of such materials in the field of electrocatalytic CO₂ reduction.