Electrochemical Reduction Of Carbon Dioxide Into Small Molecule Compounds

In recent decades,electroreduction of CO₂ is a research topic that people pay more attention to,and it has very important significance in mitigating greenhouse effect,energy crisis and so on.Most of the researchers are devoting to the electrochemical reaction using copper as the electrode,and have done a lot of research on the modification of copper.Among of these research,the Faraday efficiency of copper as the electrode mostly reaches more than 90%.However,after reviewing a large number of documents,it was found that copper was not the only metal electrode that could produce alcohols.Therefore,nickel metal was chosen to be used as the working electrode to research the electrochemical reduction of CO₂ to produce alcohols in this thesis.The nickel electrode was used as the work electrode in the experiments.platinum plate electrode as auxiliary electrode,calomel electrode as reference electrode,to explore the electrochemical reduction of CO₂ in H-cell.The experimental results showed that in 0.5 mol·L^-1 KHCO₃ solution as electrolyte,nickel electrode as cathode,CO₂ could be reduced to produce ethanol.The Faraday efficiency of ethanol was 8.721%as the electrolysis voltage was-1.6 V_vs.SCE and the electrolysis time was 6 h.Secondly,because TiO₂ has the characteristics of stable nature,low price,non-toxic and so on.In this thesis,microwave hydrothermal method was adopted to prepare TiO₂Catalyst doped Zn and Eu.The condition of microwave hydrothermal method for preparing TiO₂-Zn-Eu catalyst was:n(Zn²⁺):n(Ti⁴⁺)=0.06%,n(Eu³⁺):n(Ti⁴⁺)=0.12%,the power of microwave hydrothermal synthesis was 600 W,the temperature of microwave hydrothermal synthesis was 150?.The time of microwave hydrothermal synthesis was 2.5 h.The calcination temperature was 575?.The time of calcination was 3h.10mg catalyst was suspended in 3 mL acetone and 20?L Nafion solution and was dispersed by ultrasound.Then,the 20?L above solution was dispersed evenly on the carbon paper?1×1 cm²?by using a micro pipette and then be dried at room temperature to prepare an electrode.Using graphite electrode as auxiliary electrode and calomel electrode as reference electrode,CO₂ was electrochemically reduced in 0.5mol·L^-1 KHCO₃.The results showed that the product contained methanol by gas chromatography?GC?inspection analysis.The Faraday efficiency of methanol reached at 15.21%when the electrolysis voltage was-1.4 V_vs.SCE,and the electrolysis time was3 h.Finally,because the reduction of CO₂ in the previous experiments was done in a one-chamber electrolysis cell,therefore in this thesis,the reduction of CO₂ with brass electrodes in H-type electrolytic cells was explored.Taking brass electrodes as working electrodes,platinum sheets as an auxiliary electrode and the calomel electrode as a reference electrode,electrochemically reduction of CO₂ in 0.5 mol·L^-1 KHCO₃ solution was done.The experimental results showed that the product contained formic acid by liquid chromatography?LC?inspection analysis.The Faraday efficiency of formic acid reached at 89.48%when the electrolysis voltage was-1.8 V_vs.SCE and the electrolysis time was 3h...