Preparation Of Silver And Zinc-based Catalysts And Their Catalytic Performance For CO₂ Electroreduction

CO₂ electroreduction reaction（CO₂RR）is a hot thesis that has emerged in recent years.CO₂RR can convert carbon dioxide,the main greenhouse gas in the atmosphere,into carbon-based fuels that can be used directly by humans,solving environmental problems while develop new strategy for energy problems.However,CO₂RR is high-cost and limited by poor selectivity,low current density and instability,resulting in difficulties in commercialization.Therefore,by controlling the catalyst structure,this paper develops a catalyst of CO₂RR with good selectivity,high current density and excellent stability,then tests and evaluates its catalytic properties.This article mainly includes two aspects of aspects as follows:（1）In this paper,four silver-based catalysts are prepared.Prepare a particle size of about400nm silver oxide cube in aqueous solution,then take a portion of the silver oxide cube to vulcanize its surface with sulfur,and then wash off the remaining silver oxide with ammonia,and finally obtain a hollow cube structure of silver sulfide.In addition,we also prepared silver cubes with solvothermal method,and reduced silver sulfide hollow cubes by hydrogen atmosphere and heating conditions to obtain pure silver.The CO₂ electrocatalytic properties of the catalyst were tested with the flow phase electrolytic pool reactor of the three-electrode system,the electrolyte solution was selected from 1 M KOH aqueous solution,and the potential window was-0.19 to-0.70 V vs.RHE,the catalyst in the potential range of-0.34 to-0.70 V vs.RHE CO selectivity reached 99%,at-0.70 V vs.RHE potential,CO Faraday efficiency remained above 99%at the same time,the current density reached 421.7 m A cm^-2;The stability test selected a capacition of-0.49V vs.RHE,and the CO selectivity of maintaining 99%in this substation reached 50 hours,and the selectivity and current density were not significantly attenuated,which is expected to achieve industrial production.（2）An array of micron lines is grown on zinc foil by hydrothermal reaction,with a diameter of about 100-300 nm and a length of about 5-10μm.The hydroxide is removed by heating treatment,and the surface of zinc oxide is vulcanized,so that its appearance is covered with a layer of unsequendable zinc sulfide particles,and the surface of the oxidation leakage forms an interface structure,thereby enhancing its activity of CO₂RR and stability in alkaline electrolyte solution.The performance of the catalyst CO₂ electrocatalytic reduction was tested with the flow phase electrolytic pool reactor of the three-electrode system,the reaction was carried out at room temperature and normal pressure,the electrolyte solution was selected with1 M KOH aqueous solution,and the potential window was-0.34 to-0.73 V vs.RHE,the catalyst at-0.56 V vs.RHE point CO selectivity reached 97%,at-0.73 V vs.RHE level,CO Faraday efficiency maintained above 90%at the same time,the current density reached 300 m A cm^-2;The stability test selected a capacition of-0.56 V vs.RHE,and the CO selectivity of maintaining above 90%for 40 hours was much higher than previously reported in terms of selectivity,current density and stability.In addition we used zinc sulfide particles to do the same experiment,to verify that zinc sulfide on CO₂RR can not directly play an efficient catalytic role alone.