Preparation Of Composite Metal Electrocatalyst And Its Application In Electrochemical Reduction Of Carbon Dioxide

In recent years,the large use of carbon-containing energy has caused the increasing concentration of carbon dioxide in the atmosphere year by year,and the greenhouse effect has attracted great attention.Developing sustainable and non-fossil processes to produce fuels and chemicals is an effective method to reduce carbon dioxide emissions.A promising technology is developing electrochemical conversion processes to convert molecules in the atmosphere?such as water,carbon dioxide and nitrogen?into high-value products?such as hydrogen,hydrocarbons,oxides and ammonia?by coupling with renewable energy sources.In the process of electrochemical reduction of CO₂,electrocatalysts can greatly improve the reaction rate,efficiency and selectivity.Therefore,the development of catalytic materials with high catalytic activity,selectivity and stability is the focus of current research.Three kinds of catalysts such as Sn/f-Ni,Pb/f-Cu and Sn-Pb/f-Cu were prepared by electrochemical deposition.Scanning electron microscopy?SEM?,energy dispersive spectroscopy?EDS?,X-ray diffraction?XRD?were used to analyze the structure and elemental composition of the three catalysts.At the same time,the three catalysts were electrochemically characterized by cyclic voltammetry?CV?and potentiostatic chronocoulometry?CC?.The electrolytic potential,product Faraday efficiency and catalyst stability of electrochemical reduction of CO₂ to the syngas were also investigated.Sn/f-Ni electrode:By comparing and characterizing the samples prepared with different deposition currents,the optimal preparation conditions for the Sn/f-Ni electrode were as follows:deposition current 15 mA,deposition time 10 min;reduction potential-1.7 V vs Ag/AgCl,the Faraday efficiency of CO is 34.23%,H₂:CO is 2:1;during the three hours of electrolysis,the ratio of H₂ to CO remains unchanged;after the third cycle,the performance of the electrode will be significantly reduced.Pb/f-Cu electrode:By comparing the characterization of the samples prepared with different deposition currents,the optimal preparation conditions for the Pb/f-Cu electrode were as follows:deposition current 15 mA,deposition time 10 min;reduction potential-1.9 V vs Ag/AgCl,the Faraday efficiency of CO is 42%,H₂:CO is 1.4:1;during the three hours of electrolysis,the ratio of H2 to CO remains unchanged.Sn-Pb/f-Cu electrode:By comparing and characterizing the samples prepared with different deposition currents under different tin-lead ratios,the optimal preparation conditions for Sn-Pb/f-Cu electrode were Sn:Pb of 1:1 and deposition current of 15 mA,deposition time is 10 min;when the reduction potential is-1.7 V vs Ag/AgCl,the Faraday efficiency of CO is 50.65%,the Faraday efficiency of formic acid is about 10%,and the total Faraday efficiency of CO₂ participating in the electrochemical reduction reaction reaches 60%,at this optimal potential,H₂:CO is about 1:1.3;during the three hours of electrolysis,the ratio of H₂ to CO remains unchanged;the performance of the electrode will be reduced after use.The tin-based,lead-based and tin-lead alloy-based electrodes exhibit excellent performance for electrochemical reduction of CO2.The ratio of H2 to CO is 2:1,1.4:1,and1:1.3,respectively,all can be used as syngas for the production of more high value chemicals.