Preparation Of Diatomic Nickel/Copper Catalysts And Electrocatalytic Performance For Carbon Dioxide Reduction

As the carbon dioxide(CO₂)content in the atmosphere continues to increase,more and more environmental problems have emerged.The use of renewable energy to drive the electro-catalytic reduction of carbon dioxide(CO₂RR)can convert the greenhouse gas CO₂into fuel and various chemicals,which is an effective way to solve the greenhouse effect and energy crisis.Due to the synergistic catalytic effect of the dinuclear sites of the diatomic catalyst,the catalytic effect of the catalyst is greatly improved,which has attracted more and more attention.In this paper,by using the"bottom-up"method,first synthesize the binuclear molecular complex,and then use different methods to confine the binuclear molecular complex on the base material,remove the ligand by high temperature thermal release,and obtain the carbon and nitrogen Diatomic catalyst on the material.This paper is mainly divided into the following two parts:1.Through the"bottom-up"method,first synthesize the binuclear complex Ni₂-L₁L₂with ideal binuclear distance,mix it with carbon black and dicyandiamide ball milling uniformly,and obtain the diatomic nickel catalyst by in-situ high temperature pyrolysis.Use HAADF-STEM characterization and synchrotron radiation characterization to confirm the existence of dual-nuclear sites.Through the electrochemical performance test,it is found that Ni₂-NC has the most excellent electrocatalytic CO₂reduction activity:at-0.88 V(vs.RHE),the CO Faraday efficiency can reach 98%,at-0.68 V?-1.08 V(vs.RHE),the Faraday efficiency of CO is as high as 90%or more.The mobile phase electrolytic cell was used to explore the catalytic performance of the catalyst,and it was found that the catalytic effect of the catalyst was more excellent.At a larger current density,a Faraday efficiency of98.88%CO was obtained.Using XPS and Synchrotron radiation characterization to characterize the interactions in the binuclear nickel sites,while using N₂adsorption test,Raman test,ICP test,TEM and other characterizations to confirm that the diatomic catalyst and the monoatomic catalyst have similar structure and composition,thus explaining the catalysis The difference in effect is due to the synergistic catalysis of the dinuclear sites.The electrochemical active surface area(ECSA)test was performed on different materials,which confirmed the higher intrinsic activity of Ni₂-NC,the use of electrochemical impedance spectroscopy test confirmed that Ni₂-NC has a smaller mass transfer resistance,and the Tafel slope confirmed The diatomic complexes are more favorable in terms of kinetics.At the same time,the DFT calculation shows that the energy barrier of the reaction intermediate COOH*is reduced due to the synergistic catalysis of the dinuclear sites,indicating that the synergistic catalytic effect can greatly improve the catalytic effect.2.Through the"bottom-up"method,firstly synthesize the binuclear copper complex Cu₂-L,and use the in-situ synthesis method to confine the binuclear complex in the ZIF-8 channel and pass the in-situ pyrolysis.A highly dispersed carbon-based copper catalyst is obtained.The synthesized catalyst is used for electrocatalytic CO₂reduction and has excellent performance:at-0.8 V(vs.RHE),the CO Faraday efficiency reaches the maximum,about 80%.Compared with the comparative material catalyst Cu-NC,the catalyst Cu₂-NC has a better electrocatalytic reduction of CO₂.XRD and TEM characterization confirmed the high dispersion of Cu in the base material.XPS was used to characterize the valence state of the metal in the material,and TEM and adsorption tests were used to characterize the porous structure of the material.The electrochemical active surface area(ECSA)test was performed on different materials,which confirmed the higher intrinsic activity of Cu₂-NC,the electrochemical impedance spectroscopy test confirmed that Cu₂-NC has a smaller mass transfer resistance,and the Tafel slope confirmed The diatomic complexes are more favorable in terms of kinetics.