A Study Of The Electrochemical Reduction For Carbon Dioxide Based On Ionic Liquids

Carbon dioxide (CO2) is known to be the main greenhouse gas, also is the mostcheap and abundant carbon source. The conversion and utilization study of carbondioxide is of great significance in the world. But the thermodynamic characteristic ofcarbon dioxide is stability and difficult to active, the traditional activation of CO2should be carried out under the condition of high temperature and high pressure.Electrochemical activation of CO2is directly through the electronic as reaction reagentunder a mild condition. It is also a simple procedure, an environment friendly and anattractive approach to fixation of CO2.In this paper, based on the principle of modifiedelectrodes, the improved performance for carbon dioxide electrochemical reductionwas investigated. What the thesis researched was summarized as follows:(1) In this thesis, the study progress of the conversion and utilization strategiesfor carbon dioxide were reviewed, the effect of the electrode materials and electrolytesolution for CO2electro-reduction was explained in detail, the nature of the ionicliquid and the applications of the ionic liquid for CO2in fixation was also introduced.(2) The poly ionic liquid poly[Dbz-mim]Cl was prepared through2-methylimidazole and1,5-dichloro-2,4-dinitrobenzene by chemical polymerizationfor modified electrode. The poly ionic liquid poly[bzmim]PF6was prepared through[bzmim]PF6by electrochemical method on electrode surface. The ionic liquid polymerwas characterized by1H NMR,13C NMR and IR.(3) The poly[Dbz-mim]Cl/foam nickel modified electrode andgraphite-poly[Dbz-mim]Cl/foam nickel modified electrode were prepared by chemicalpolymerization. The prepared polymer film modified electrodes showed goodelectro-catalytic activity. Under the mild conditions, the electrochemical reduction ofcarbon dioxide on modified electrodes in ionic liquid1-butyl-3-methylimdazoliumhexafluorophosphate [bmim]PF6was researched in three electrodes undividedelectrolytic cell. The electrode materials, scanning speed, temperature and stirringcondition for carbon dioxide electro-catalytic reduction was investigated. Themodified electrodes were applied to electric-catalytic reduction of carbon dioxide, theresults showed that poly[Dbz-mim]Cl/foam nickel modified electrode can obviouslyreduce the reduction potential of carbon dioxide, the reduction potential of carbondioxide was around-1.2V. The reduction potential of the graphite-poly[Dbz-mim]Cl/foam nickel modified electrode for carbon dioxide wasfurther down to-0.68V, which showed that the better catalytic reduction activity.(4) The poly[bzmim]PF6/Au modified electrode and TiO2-poly[bzmim]PF6/Aumodified electrode were prepared by electrochemical method. The electrochemicalactivity of the two modified electrodes for carbon dioxide was investigated by thecyclic voltammetry under the mild conditions in three electrodes undivided electrolyticcell. The experiments at different scanning speed and temperature were carried out.The stirring condition for carbon dioxide electro-catalytic reduction was alsoinvestigated. The modified electrodes were applied to electrochemical reduction ofcarbon dioxide, the study results showed that poly[bzmim]PF6/Au modified electrodealso can reduce the reduction potential of carbon dioxide, the reduction potential ofcarbon dioxide was around-1.44V. The reduction potential of theTiO2-poly[bzmim]PF6/Au modified electrode for carbon dioxide was further down to-0.95V, which improved the electrochemical reduction activity of modified electrodefor carbon dioxide.