在金银电极上电解二氧化碳制备一氧化碳的研究

发布时间：2018-08-26 19:38

【摘要】：C02是主要的温室气体,也是自然界最重要和最丰富的一种碳源。将C02转化为有用化学品,减少化石燃料的使用量,是实现C02减排的重要途径之一。本论文采用新型隔膜电解池,分别在KHCO3水溶液、四丁基高氯酸铵(TBAP)/二甲基亚砜(DMSO)溶液和四丁基高氯酸铵(TBAP)/碳酸丙烯酯(PC)溶液中,研究了C02在Au、Ag电极上的电化学还原反应,分析了CO2在Ag电极上发生电还原反应的电极失活机理,探索了CO2在非水体系电解液中的电还原行为。主要研究内容如下：(1)利用循环伏安、塔菲尔曲线、恒电位电解和气相色谱等方法,研究了C02在Au、Ag电极上发生电还原反应的动力学特征。结果表明,在KHCO3水溶液中,CO2可以发生电还原反应,生成CO。在Au、Ag电极上CO2电还原反应的交换电流密度分别为4.014×10-4A/cm2、3.011×10-4A/cm2,平衡电位分别为-0.720V、-0.934V,最高电流效率分别可达84%和67%。(2)利用线性扫描、塔菲尔曲线、恒电位电解、扫描电镜、电化学阻抗谱和X射线光电子能谱(XPS)等方法,分析了CO2在Ag电极上发生电还原反应的电极失活机理。结果表明,在CO2电还原反应过程中,一些有害物质附着在电极表面上,导致生成CO的平衡电位负移,交换电流密度变小,电荷转移电阻增大,电流效率和电流密度迅速降低。X射线光电子能谱(XPS)分析结果表明,阴极表面的附着物为石墨碳和微量Zn。(3)利用循环伏安曲线、恒电位电解曲线、电化学阻抗谱和气相色谱分析等方法,研究了CO2在非水体系电解液中的电还原行为。结果表明,在TBAP/DMSO溶液和TBAP/PC溶液中,CO2电还原反应的电流密度分别只有3.2mA/cm2和4.5mA/cm2, Ag电极的失活并不严重。电化学阻抗谱分析结果表明,上述两种电解液的电极过程均由电荷传递和扩散过程共同控制。电还原反应刚开始时,C02在TBAP/DMSO溶液和TBAP/PC溶液中电还原生成CO的电流效率分别可达到87%和89%。在长时间的电还原过程中,Ag电极一直保持着很高的催化活性,2h的电解后电流效率仍分别为81.3%和83%。
[Abstract]:CO2 is the main greenhouse gas and the most important and abundant carbon source in nature. Converting CO2 into useful chemicals and reducing the use of fossil fuels is one of the important ways to reduce CO2 emissions. In this paper, the electrochemical reduction reaction of C02 on Au,Ag electrode was studied in KHCO3 aqueous solution, tetraDing Ji ammonium perchlorate (TBAP) / dimethyl sulfoxide (DMSO) solution and (TBAP) / propylene carbonate (PC) solution, respectively. The electroreduction mechanism of CO2 on Ag electrode was analyzed, and the electroreduction behavior of CO2 in non-aqueous electrolyte was explored. The main contents are as follows: (1) using cyclic voltammetry, Taffer curve, potentiostatic electrolysis and gas chromatography, the kinetic characteristics of electrochemical reduction of CO2 on Au,Ag electrode were studied. The results show that CO _ 2 can be electroreduced to form CO. in KHCO3 aqueous solution. The exchange current density of CO2 electroreduction reaction on Au,Ag electrode is 4.014 脳 10 ~ (-4) A / cm ~ (-2) and the equilibrium potential is -0.720 V / cm ~ (-0.934) V, respectively. The maximum current efficiency is 84% and 67%, respectively. (2) by linear scanning, Taffel curve, potentiostatic electrolysis, scanning electron microscope, Electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) were used to analyze the deactivation mechanism of electroreduction reaction of CO2 on Ag electrode. The results show that during the electroreduction of CO2, some harmful substances are attached to the electrode surface, which leads to the negative shift of the equilibrium potential for the formation of CO, the decrease of the exchange current density and the increase of the charge transfer resistance. The results of X-ray photoelectron spectroscopy (XPS) analysis show that the attached materials on the cathode surface are graphite carbon and trace Zn. (3) using cyclic voltammetry curve and constant potential electrolysis curve. Electrochemical impedance spectroscopy (EIS) and gas chromatographic analysis (GC) were used to study the electroreduction behavior of CO2 in non-aqueous electrolyte. The results show that the current density of CO _ 2 electroreduction in TBAP/DMSO solution and TBAP/PC solution is only 3.2mA/cm2 and 4.5 Ma / cm ~ 2, respectively. The deactivation of Ag electrode is not serious. The results of electrochemical impedance spectroscopy show that the electrode process of the two kinds of electrolytes is controlled by charge transfer and diffusion process. At the beginning of the electroreduction reaction, the current efficiency of electroreduction of C02 to CO in TBAP/DMSO solution and TBAP/PC solution was up to 87% and 89%, respectively. During the long time electroreduction, the electrolysis current efficiency of Ag electrode was 81.3% and 833%, respectively, after electrolysis with high catalytic activity for 2 h.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ127.12

【参考文献】