PtRu/C催化剂上甲醇电氧化的电化学阻抗谱  

Electrochemical Impedance Spectroscopy of Methanol Electrooxidation on PtRu/C Catalysts

作　　者：武刚[1] 李莉[1] 徐柏庆[1] 

机构地区：[1]清华大学化学系,有机光电子与分子工程教育部重点实验室分子催化与定向转化研究室,北京100084

出　　处：《高等学校化学学报》2005年第4期715-718,共4页Chemical Journal of Chinese Universities

基　　金：国家重点基础理论研究发展计划"九七三"项目(批准号:G2000026408);中国博士后科学基金(批准号:20040350300);国家自然科学基金(批准号:20125310)资助.

摘　　要：利用电化学阻抗谱(EIS)研究了甲醇在不同电化学极化处理后的PtRu/C催化剂上的电氧化动力学参数.通过交流阻抗理论的分析,从理论上研究了不同电势区间(低、中、高)内反应中间产物的表面覆盖率随电极电势的变化规律以及对反应法拉第电流的影响,较好地解释了甲醇电氧化实验中的动力学规律在低电势区,甲醇分子脱除第一个氢原子的基元反应,即第一个电子的传递反应为速率控制步骤,而在高电势区,反应中间产物COads的氧化脱除则为速率控制步骤.The kinetic parameters of methanol electrooxidation on PtRu/C catalysts were investigated by electrochemistry impedance spectroscopy(EIS). The results from EIS at various potentials reveal that the cathodic polarization would contribute to enhancing methanol electrooxidation activity. The impedance behavior of methanol electrooxidation on PtRu/C catalysts at different potentials can be well explained by using the deduced kinetic theory involving one intermediate adsorbate. At low potentials, splitting of the first C-H bond of CH_3OH molecule with the first electron transfer is rate-determining step on various PtRu/C electrocatalysts, while at higher potentials, the oxidation reaction of CO_~ads gradually becomes rate-determining step. The change of intermediate CO_~ads coverage and its effect on faradic current of methanol electrooxidation were also discussed according to experimental and theoretical results from EIS.

关 键 词：甲醇 电氧化 PtRu/C催化剂 交流阻抗谱 

分 类 号：O646[理学—物理化学]