Synthesis Of Metal/Metal Oxide （M=Cu,Cd,Ag,In） Catalysts And Their Electrocatalytic Performances For CO₂ Reduction

Electrocatalytic reduction of carbon dioxide（CO₂RR）into valuable industrial chemicals or fuels has become an emerging technology and an effective way to solve the problem of rising carbon dioxide emissions in the atmosphere.However,CO₂is a linear molecule with two equal carbon-oxygen bonds（C=O）,so it is inert in dynamics.Therefore,it is necessary to develop catalysts with high activity to reduce the reaction activation energy and enhance the reaction rate of electrochemical CO₂reduction.In this work,carbon fiber（CF）/carbon black（Vulcan XC-72R）were used as the carriers,and Cu,Ag,Cd,In as active metal componentsare,to synthesize the electrocatalysts with different morphologies.The effects of two-component non-noble metal catalysts on the catalytic performance of electrocatalytic CO₂reduction were studied.The main results are listed as follows:1.Three different catalysts were obtained using facile methods:The Cu-Cd/CF and Ag-Cd/CF were synthesized by cyclic voltammetry electrodeposition,respectively.The CuO-In（PO₃）₃/C was synthesized by wet-chemical method.The composition and surface chemical states of as-synthesized catalysts were analyzed with XRD and XPS spectra,and the morphology and microstructure were observed by SEM,TEM,HAADF-STEM.It is showed that:（1）Cu-Cd nanoparticles deposited on carbon fiber are in the shape of corn granular,with large active specific surface area and abundant catalytic active sites.（2）The bimetallic Ag-Cd particles loaded on the carbon fiber exhibit flower-flake of Cd and dendrite-like of Ag.Zero-valent Ag and Cd are the dominant ingredients.The binding strength between active sites and intermediate*COOH is enhanced,which makes it easy to escape from the catalyst surface to form CO,achieving better catalytic performance.（3）The morphology of CuO-In（PO₃）₃/C is rod-like structure,and the main components are CuO and In（PO₃）₃which are both uniformly dispersed on the carbon black,with a large active surface area.2.Investigation based on linear sweep curve（LSV）,chronoamperometry test（I-T）,electrochemical active surface area（ECSA）and electrochemical impedance（EIS）measurements gave the results displayed as follows:（1）Cu-Cd/CF catalyst exhibited higher catalytic selectivity for CO,and the Faraday efficiency（FE）reached 97.27%at-0.536 V vs.RHE potential,with a superior stability within 10 h.（2）Ag-Cd/CF catalyst showed high CO selectivity and good stability over a wide potential range（-0.586 V vs.RHE～-0.986 V vs.RHE）.The best CO selectivity can be obtained at-0.586 V vs.RHE potential with FE_COof 89.38%.In addition,Ag-Cd/CF（PEI）by loading Ag-Cd on CF pretreated with PEI can significantly improve the current density,especially,FE of syngas can reached 100%with a controlled proportions of H₂/CO.（3）Compared with CuO/C and In（PO₃）₃/C,CuO-In（PO₃）₃/C was more prone to catalyze CO₂into CO,and exhibited a lower starting point（-0.486 V vs.RHE）.The best CO selectivity was obtained at-0.586 V vs.RHE with FEco of 88.50%.It should be noted that the total current density of CuO-In（PO₃）₃/C catalyst can reach-178.09m A·cm^-2at-0.886 V vs.RHE when the flow cell was used as the electrolytic reactor.In summary,Cu-Cd/CF,Ag-Cd/CF,CuO-In（PO₃）₃/C catalysts with different morphologies were synthesized and all showed good catalytic performance towards CO₂RR,with low overpotential,high selectivity and stability.The research results in this work will provide a new strategy and some scientific&experimental basis for the design of CO₂RR electrocatalyst by simple synthesis method.