Au电极上CO_2电还原过程中电极失活原因  

Deactivation Mechanism of Au Electrode in Electrochemical Reduction of CO_2

作　　者：王琴[1] 王晓春[2] 杨冬伟[2] 李露[2] 贾友见[1] 施锦[2] 

机构地区：[1]昆明理工大学理学院,云南昆明650500 [2]昆明理工大学冶金与能源工程学院,云南昆明650093

出　　处：《化学反应工程与工艺》2015年第4期352-358,共7页Chemical Reaction Engineering and Technology

基　　金：国家自然科学基金项目(51164020)

摘　　要：在水溶液中,电还原CO_2制取CO时,电极易中毒失活,采用扫描电子显微镜(SEM)、X射线光电子能谱(XPS)对反应前后的电极材料进行检测,研究CO_2在KHCO_3水溶液中发生电化学还原反应时,Au电极失活原因及电极材料活性降低对反应过程的影响。结果表明,电极表面吸附了一层黑色有害物质。这层黑色有害物质大部分是石墨碳,并有微量的铁和锌。采用塔菲尔曲线、电化学阻抗(EIS)、线性扫描曲线、恒电位电解和气相色谱法等研究了有害物质对CO_2电还原反应动力学过程的影响,发现随着反应的进行,生成CO的平衡电位负移,电荷转移电阻增大,交换电流密度变小,产物CO的电流效率迅速降低。说明电极表面附着的有害物质使电极材料活性降低,阻碍了CO_2电还原反应的进行。The working electrode might get inactivate easily in the process of electrochemical reduction of CO2 to CO in aqueous solution. The effects of the deactivation reasons of the Au electrode and the decrease of electrode activity on the reaction during the electrochemical reduction of CO2 in KHCO3 aqueous solution, and the surface of Au electrode were investigated by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS).The results showed that a small amount of impurities composed of C graphite and a little of Fe and Zn adsorbed on the surface of the Au electrode. The electrochemical kinetic characteristics of CO2 reduction on Au electrode were studied using Tafel curve, Electrochemical impedance spectroscopy(EIS), Linear sweep curve, Potentiostatic electrolysis, and gas chromatographic. As a result, with the reaction going on, the equilibrium potential of CO2 conversion to CO shifted to negative, the electron transfer resistance rised up, the exchange current density reduced continuously, and the faradaic efficiency of CO decreased rapidly, which indicated that C graphite and metal adsorbed on the electrode decreased the electrocatalytic activity of Au electrode, and hindered the CO2 reduction.

关 键 词：二氧化碳 电化学还原 中毒机理 电极失活 

分 类 号：TQ151.51[化学工程—电化学工业]