Preparation And Performance Of Copper-Based Bimetallic Catalysts For Electrocatalytic Of CO₂ To C_xH_y

Hydrocarbons in electrocatalytic CO₂ reduction products have the advantage of high hydrogen storage energy density,while Cu is the only metal that can directly electrocatalytically reduce CO₂ to hydrocarbon products among traditional single metals.The research on the modification of Cu-based catalysts has become the focus of attention in the field of electrocatalytic CO₂ reduction.Among various strategies,Cu-based bimetallic catalysts have the characteristics of many optional elements,controllable proportions,and the ability to change the geometry and electronic structure of the bulk,which makes this method show great research value.At present,most of the selected metals are noble metals or metals with little difference in activity with Cu,such as Ag,Sn,In and Bi,and the reduction products of the bimetallic catalysts are mainly CO or HCOOH.However,Cu-based bimetallic catalysts that select active metals whose redox potential is much lower than Cu（such as rare earth metals and common active metals）are less studied.At the same time,Cu-based bimetallic catalysts have the problems of poor selectivity,low activity and poor stability for electrocatalytic CO₂ reduction to hydrocarbon products.In view of the above problems,this paper explores the CO₂ reduction performance of bimetallic catalysts prepared by different active metals and Cu,constructs efficient active centers,analyzes the influence on the changes of Cu electronic structure and specific intermediates,and reveals the mechanism of Cu-based bimetallic catalytic CO₂reduction.The specific research contents are as follows:Using europium nitrate and copper acetate as precursors,the well-dispersed core-shell Cu@CuEuO_x nanoparticles（Cu@CuEuO_x NPs）catalysts was prepared by solvothermal synthesis.It is found that the Cu@CuEuO_x NPs surface is amorphous composite oxide shell structure.By controlling the doping amount of metal salt,Cu@CuEuO_x NPs catalysts with different Eu content in the shell layer and different CO₂ reduction performance can be obtained.In the H-type electrolyzer,the Faradaic efficiency of CH₄ can reach 74.7%at-1.2V vs RHE,and its current density is 45.4m A cm^-2.The research results related to the reaction mechanism show that the amorphous CuEuO_x surface of Cu@CuEuO_x NPs catalysts effectively increases the electrochemical active area of the catalyst surface,and the formed Ov is beneficial to the activation and adsorption of CO₂ molecules.The Cu active site has lower electron density under the influence of surrounding Eu and enhances the stabilization of the intermediate*CHO.Using copper acetate and cerium acetate as metal precursors,Ce-doped Cu NPs（Ce-Cu NPs）catalysts were prepared by one-step thermal reduction method.Ce-Cu NPs with different doping amounts were prepared by controlling the doping amount of metal salts to achieve highly selective catalytic reduction of CO₂ to C₂H₄.The study shows that Ce of Ce-Cu NPs catalyst can maintain a mixed ionic state in the process of CO₂ reduction,and the presence of O_v is beneficial to the activation of CO₂reactant.In addition,Ce can change the local electron distribution of Cu through the electronic effect of its ionic valence,further stabilize Cu⁺and promote C-C coupling.At a current density of 150 m A cm^-2 in the flow electrolyzer,the Faradaic efficiency of C₂H₄ of the Ce-Cu-2 NPs catalysts can reach 53%,which is nearly 2.8 times that of the Cu NPs catalysts.Using copper nitrate and aluminum nitrate as metal ion sources and 2-aminoterephthalic acid as organic ligand,Al_yCu-NBDC precursors with different Al contents were prepared by adjusting different proportions of metal salts.Then,Al_x-Cu/N-C composites were prepared by the method of bimetallic organic compound derivations and pyrolysis at high temperature in a mood atmosphere.The results show that the particle size of Cu nanoparticles in Al_0.05-Cu/N-C composites is about 48 nm,and the particles are uniformly distributed on the surface of the porous N-containing substrate.The doping of Al makes Cu grains refined and has better dispersibility,and increases the content of active nitrogen in carbon substrate.The Cu nanoparticles interacted with the carrier through M-N-C to generate charge transfer,change the electronic state of Cu,form electron-deficient Cu active centers on the Cu nanoparticles,improve their CO adsorption capacity,and promote the selective conversion of electrocatalytic CO₂ to C₂H₄.At a current density of 150 m A cm^-2 in the flow electrolyzer,the Faraday efficiency of Al_0.05-Cu/N-C composites for C₂H₄ is up to 51%,and could operate for 6 h.