Computational Study Of Carbon Dioxide Electrochemical Reduction By Copper-gold Alloy

The electroreduction of carbon dioxide into high-value carbon-containing products has extremely high environmental protection and economic value.Copper-based catalysts have received extensive attention from researchers due to their unique selectivity to C2 products.Due to the non-specific active components and selectivity of monometallic copper,current researchers usually use particle size reduction,surface modification,alloying and other solutions to further improve the performance of copper-based catalysts.The production performance of C2 products varies with the copper-gold ratio,but the C-C connection conditions in the process,the selectivity of C2 products,and the reaction mechanism of catalytic carbon-electric reduction are still unclear.To proceed,this thesis adopts the density functional theory to select the two optimal exposed crystal planes((100)planes with three different ratios of copper-gold alloys(Cu:Au = 1:3,1:1,3:1)(111)surface),systematically studied carbon dioxide electroreduction mechanism at each point on six surfaces.The reason for the difference in performance;then,this paper analyzes the carbon-carbon exchange performance of each surface;finally,the two copper-gold alloy surfaces with the best C-C dimerization ability are selected and the reaction path to ethylene and ethanol is more and more explored.The specific research content is as follows:(1)Computational research of CuAu alloys for CO2ER to CO:density functional theory was applied to study the adsorption behaviors of intermediates on six alloy surfaces and four pure metal surfaces as a comparison.The results show that the bridge sites of the alloy(100)plane can help stabilize*CO.Among the alloys,Cu1Au3(100)has the lowest CO generation energy barrier and the highest hydrogen precipitation reaction energy barrier,so it has the best CO generation performance.Apart from this,the calculation of electronic properties shows that the d-band centers of Cu and Au on Cu1Au3(100)are both closest to the Fermi level.(2)Computational research of CuAu alloys for CO2ER to C2 products:density functional theory was performed,using energy as an indicator,transforming into three C1 intermediates*CO+ on four-fold sites on the surface of six alloys*CO,*CO+*CHO,*CO+*COH interconnect performance.The optimal path is*COCOH hydrogenation dehydration to form*CCO,and then continuous hydrogenation to*OCHCH2,the next step of hydrogenation of the intermediate to form*CH3CHO or*O+ C2H4 will become the selective bifurcation point of C2H4 and C2H5OH.As a result,the Cu3Au1(100)surface has the highest ethanol selectivity.