Design And Synthesis Of Novel Copper-based Catalysts And Their Applications In Electrocatalytic Reduction Of Carbon Dioxide

The synthesis of energy products or high value-added chemical products with CO₂as chemical raw materials has dual significance of environmental protection and resource utilization,which is an important research subject.Among various CO₂conversion methods,electrocatalytic CO₂ reduction（e CO₂RR）is an important technology with many application prospects.As the core component of electrocatalytic CO₂ reduction,the efficient catalyst is the key to improving the reaction rate and product selectivity.It plays an important role in the electrocatalytic CO₂ reduction transformation.In this paper,a series of high-efficiency Cu-based catalysts were synthesized through the design and modification,and they were applied to the selective electrocatalytic reduction of CO₂ into a variety of high value-added chemicals.The main research contents and innovation points are as follows:（1）A series of porous Cu-Sb bimetallic catalysts were designed and synthesized by the low-temperature reduction method and used for electrocatalytic reduction of CO₂to produce C₂H₄.The results show that the composition of Cu-Sb catalysts had a significant effect on catalytic activity and C₂H₄ selectivity.Especially,using Cu₁₀-Sb₁catalyst as electrode material and 0.1 M KCl aqueous solution as electrolyte,the total current density of the reaction could reach 28.5 m A cm^-2 with a C₂H₄Faradaic efficiency（FE）of 50%at the applied potential of-1.19 V vs.RHE.The synergistic effect between Cu and Sb could enhance the catalytic activity of the catalysts,and the electron configuration could promote the C-C coupling at the electrode surface.（2）A new strategy of hierarchical electrodeposition is designed,which can be used to prepare a variety of three-dimensional（3D）metal-polymer hybrid materials.These catalysts had good selectivity and catalytic activity for electrocatalytic reduction of CO₂to C₂H₄,CO,and HCOOH,respectively.Especially,using Cu/PANI（Cu/polyaniline）deposited on carbon paper（CP）as working electrode and 0.1 M KCl aqueous solution as electrolyte,CO₂ could be effectively reduced to C₂H₄.The current density and C₂H₄FE could reach 30.2 m A cm^-2 and 59.4%,respectively.Control experiments and the Density-Functional-Theory（DFT）calculations showed that the in-situ synthesis strategy and the 3D structure were the key to improving electrocatalytic performance.The 3D structure was also beneficial to the high dispersion of metal,inhibiting metal aggregation,and improving the stability of catalytic materials.（3）The doped multimetallic catalyst was prepared by a one-step electrodeposition strategy,and its electrocatalytic performance for CO₂ reduction was studied.It was found that different combinations of metals had a significant influence on the electrocatalytic CO₂ reduction to C₂H₄.Especially,in 0.1 M KCl solution and H-type electrolytic cell,using Cu₁₀La₁Cs₁ ternary composite as the electrocatalyst,the FE and current density of C₂H₄ could reach 56.9%and 21.32 m A cm^-2,respectively.In a flow cell,the Cu₁₀La₁Cs₁ electrode had a C₂₊selectivity of up to 70.5%at a low reduction potential of-0.97 V vs.RHE with a current density of 485.5 m A cm^-2 using 1 M KOH as electrolyte.The C₂₊product consisted of C₂H₄（42.1%）,ethanol（20.8%）and n-propanol（7.6%）.Control experiments and theoretical calculations showed that the doping of La and Cs into Cu dramatically regulated the electronic structure of the Cu.These tactics improved the current density during the reaction process and promoted the C-C coupling to C₂₊products.（4）Three-dimensional porous Cu/Zn bimetallic heterojunction catalysts were rapidly synthesized by the hydrogen bubble template method and used for electrocatalytic reduction of CO₂ to CO.The results showed that the pore structure of the catalyst could be effectively regulated by the dynamic template to achieve a stable interfacial microenvironment for CO₂ reduction.Especially,using Cu/Zn bimetallic catalyst as electrode material and an ionic liquid/acetonitrile solution as the electrolyte,the FE of CO could reach 99.5%with a current density of 91.8 m A cm^-2 at-2.1 V vs.Ag/Ag⁺potential.In addition,the CO partial current density was 165.5 m A cm^-2 at-2.5V vs.Ag/Ag⁺.Control experiments and theoretical calculations showed that the 3D porous Cu/Zn heterojunction material had the characteristics of high activity and fast electron transfer,which could reduce the energy barrier for the formation of reaction intermediates and effectively improve the catalytic activity.