中文摘要：

粗糙银（Ag（r））电极对水溶液中3,4,5,6-四氯吡啶甲酸（Te CP）脱氯反应具有非凡的催化作用,这与非质子溶剂中氯代有机物的电化学还原的报导结论截然相反。为充分认识水溶液中银电极对3,4,5,6-四氯吡啶甲酸的电化学还原反应非凡的催化作用,我们基于表面分析、原位电化学研究和理论计算这三点进行了综合研究。本文首先采用透射电子显微镜（TEM）和X射线光电子能谱（XPS）观察了粗糙银的表面结构和化学状态。实验结果表明,氧化还原循环过程中,电极表面会形成银纳米粒子,从而导致表面无序程度的增加。我们还分别做了针对第一个电子转移过程的密度泛函理论（DFT）计算、电化学原位表面增强拉曼光谱（SERS）研究以及加入H＋的循环伏安法（CV）实验来表征不同电位区间电极表面的物质变化。实验结果表明银可以催化Te CP脱氯的第一个电子转移步骤。这是因为其自由基中间产物（TeCP^（＊-））可以比Te CP更强烈地吸附在Ag（r）电极表面。脱氯反应的关键中间体TeCP^（＊-）的存在表明Te CP在银电极上的反应路径不同于在玻碳（GC）电极的外层电子转移还原。

英文摘要：

Dechlorination of 3,4,5,6-tetrachloropicolinic acid（Te CP） on roughened silver（Ag（r）） cathodes provides an unexpected example showing extraordinary catalytic effect in aqueous solution, which is counter to what has been reported in electrochemical reduction of organic halides using aprotic media. To fully recognize this extraordinary catalytic effect of silver cathodes on electrochemical reduction of 3,4,5,6-tetrachloropicolinic acid in aqueous solutions, we conduct a comprehensive study from the aspect of surface characterization, in situ electrochemical study, and theoretical calculation. Transmission electron microscopy（TEM） images and X-ray photoelectron spectroscopy（XPS） spectra are presented to observe the surface structure and chemical state of Ag（r）. Experimental results show that Ag nanoparticle can be formed in the oxidation-reduction cyclic（ORC） process, which leads to an increase in the degree of surface disorder. Density functional theory（DFT）calculations of the first electron transfer（ET） process, integrated with an in situ electrochemical surfaceenhanced Raman spectroscopy（SERS） study and a cyclic voltammetry（CV） experiment with the aid of H＋, were performed to characterize various surface species in different electrode potential regions. Experimental evidence shows that the first ET process is catalyzed by silver for the radical derivate（Te CP~（＊-）） formed by the ET process is adsorbed more strongly than Te CP. TeCP（ads）~（＊-）is the key intermediate of the dechlorination process, implying that the dechlorination mechanism could drastically differ from the outer-sphere reduction at the glass carbon（GC） electrode.