Preparation And Study On CO₂ Electrochemical Reduction Performance Of Metal-organic Framework-derived Materials

CO₂ is largely released into the atmosphere due to the overexploitation of fossil energy.Thus,it is an effective way to capture and convert CO₂to fossil fuels or high-value-added chemicals to solve environmental problems and energy crisis.Electrochemical reduction of CO₂ provides a new strategy for solving environmental energy problem because of the mild reaction conditions and highly economic feasibility.However,the stable and efficient catalysts are still key factor in the electrochemical reduction reaction of CO₂.Metal-organic framework（MOF）and its derivatives have great potential for application in electrocatalysts because of their excellent physical and chemical properties,such as high specific surface area,controllable pore structure and adjustable chemical properties.Nevertheless,the C₁ chemicals are main products of electrochemical reduction reaction of CO₂for most MOF,especially formic acid and carbon monoxide,while alcohols with higher economic value are relatively few.Therefore,it is of great significance to rationally design geometric structure of MOF improve the catalytic efficiency for alcohols with high selectivity in the electrochemical reduction reaction of CO₂.The research will focus on the structural design of MOF-derived materials.（1）Preparation of catalyst derived from GO/ZIF-L compound with oriented structure supported Cu/Cu₂O nanoparticles and its electrochemical reduction of CO₂The catalyst that vertically arranged zeolite imidazolate framework-L derived graphene-based nanocomposite supported Cu/Cu₂O nanoparticles was prepared（Cu GNC-VL）by heat treatment.Graphene oxide（GO）serves as the substrate for the growth of two-dimensional Zeolite imidazolate framework-L（ZIF-L）.Cu/Cu₂O nanoparticles derived from the reduction of introduced Cu²⁺uniformly loaded on arranged vertically ZIF-L that in-situ growth on the surface of GO was achieved after1000℃heat treatment.Cu/Cu₂O nanocomposite crystals benefits from the synergy between CO₂ asymmetric chemical adsorption on Cu（111）and favorable kinetics and thermodynamics of C-C coupling on Cu₂O（111）on Cu GNC-VL.Equally important is the fact that Cu GNC-VL was constructed a continuous conductive network derived from GO/ZIF-L nanocomplex with vertical structure.The related tests of electrochemical properties were measured that Cu GNC-VL presented a higher yield of alcohols with an excellent faradaic efficiency of 70.52%and current density of 10.4m A cm^-2 compared with pyrolyzed ZIF-L and Cu ZIF-L@GO after electrolysis experiments at-0.87 V versus the reversible hydrogen electrode in KHCO₃ aqueous solution.（2）Preparation of Cu（I）-MOF（Cu Tz-1）and its electrochemical reduction of CO₂The Cu Tz-1-derived catalysts were prepared by heat treatment at different temperature.Cu Tz-1,rice-shaped nanoparticles with three different Cu（I）coordination structure,was synthesized by 3,5-diphenyl-1,2,4-triazole and Cu⁺precursor in methanol solution.The Cu（I）transition metal node is the key to improving the electrocatalytic performance of Cu Tz-1 300,volatilizing the small organic molecules,water molecules and impurities in the framework after low-temperature carbonization,which promotes the transfer of substances in the pore channels.In terms of catalytic conductivity and electron transfer,Cu Tz-1 300 is better than the original and other carbon materials carbonized at higher temperature.Combined with the calculation results of density functional theory（DFT）,this experiment further explained the mechanism of catalytic reaction,theoretically proving the possibility of high-selectively generating methanol.It was found that Cu Tz-1 300 could convert CO₂to methanol with a high selectivity after electrolysis in KHCO₃aqueous solution.