The Properties Research Of Imidazolium-based Ionic Liquids And Their Applications For Carbon Dioxide Electrochemical Reduction

With the rapid development of industry,the emission of greenhouse gas CO₂ is increasing year by year,and China produces nearly one billion tons of carbon dioxide every year.How to transform such a large amount of CO₂ is becoming an important research topic.As one of the most promising ways,electrochemical reduction of CO₂ can not only utilize CO₂,but also can storage and transportation of renewable energy.Due to its low steam,stable properties,structure,adjustable,large CO₂ saturated absorption,wide electrochemical window,etc,ionic liquid has caused more and more attention,and its physical properties has an important guiding role in the application of electrochemical.In this paper,the physical properties of imidazole ionic liquids with different anions were studied,and the BF4 ionic liquids that suitable for electrochemical reduction of CO2were selected by comparison.The effect of ionic liquid concentration on physical properties was studied by mixing three kinds of BF₄ ionic liquids with aqueous solvent.Based on the above physical research,we select two kinds of solutions of ionic liquid with high concentration and low concentration to study the process of CO₂ electrochemical reduction?1?In high concentration of[Emim][BF4],[Pmim][BF4]ionic liquid aqueous solutions,select concentration of 90%,70%,50%and pure ionic liquids to carry out experiment with cyclic voltammetry.The influence of mole percentage of ionic liquid on the reduction mechanism of CO₂ are discussed,the research found that when water content increasing,the reduction potential in advance gradually,and the reduction current increase gradually.?2?In low concentration of ionic liquids aqueous solution,choice concentration of0.1⁰.5 mol/l ionic liquid to conduct cyclic voltammetry test and chronocoulometry test,Through comparing the calculated efficiency of Faraday found that with the increase of concentration of ionic liquids,Faraday efficiency is also a trend of increase,under the same concentration,[Emim][BF₄]Faraday high efficiency can reach 84%Based on the above research,we designed and synthesized a kind of amine functionalized ionic liquids-[NH₂pim][BF₄],and explore the CO₂ absorption properties and electrochemical reduction efficiency.Through the experiment found that the cationic amino groups on imidazole ring has interaction on CO₂.Under the interaction of amino groups with CO2,so CO2 can get more conducive to further reducing generation product,it makes the Faraday efficiency up to 94.9%.