中文摘要：

采用不同体积分数的硝酸溶液（8%、15%、20%、68%）对多壁碳纳米管（MWNTs）进行预处理,使用甲醛还原方法制备出Pd/MWNTs催化剂,利用Boehm滴定法、红外光谱分析、X射线衍射（XRD）、扫描电子显微镜（SEM）及循环伏安曲线（CV）对催化剂进行表征分析,并制备成Pd/MWNTs催化阴极,在隔膜电解体系中对4-氯酚进行降解研究.结果表明,随着硝酸体积分数的增加,预处理后碳纳米管表面酸性基团的数量呈上升趋势,经过68%硝酸预处理2 h后,酸性基团的量达到2.3mmol/g,羧基数量达到0.38 mmol/g.制得的Pd/MWNTs催化剂上金属Pd粒径大小为9.2 nm,高度分散在碳纳米管表面;在碳纳米管上负载金属Pd可以促进H2O2的生成,同时做为电极使用时可以减小外加电压,降低能耗.Pd/MWNTs催化电极对4-氯酚有较好的降解效果,在前80 min通氢气条件下,阴极室发生还原性脱氯反应,后60 min通入空气,阴阳极室发生了氧化反应,4-氯酚转化率和TOC去除率分别达到86.9%和71.6%.

英文摘要：

Nitric acid in various volume fraction（8%,15%,20%,and 68%） was used on the multi-wall carbon nanotubes（MWNTs） pre-treatment and then the formaldehyde reduction method was utilized for the preparation the Pd/MWNTs catalysts which were fully characterized by Boehm titration method,X-ray diffraction（XRD）,infrared spectroscopy,scanning electron microscopy（SEM）,and cyclic voltammetry（CV） techniques.The electrochemical degradation of 4-chlorophenol was investigated in a diaphragm electrolysis system using the Pd/MWNTs gas-diffusion cathode.The results indicated that the active organic function groups increased on the surface of the carbon nanotube pre-treated by using 68% nitric acid.Pd particles with an average size of 9.2 nm were highly dispersed in the carbon nanotube with an amorphous structure.Additionally,the Pd/MWNTs catalyst in Pd/MWNTs gas-diffusion electrode system accelerated the two-electron reduction of O2 to hydrogen peroxide（H2O2） when feeding air.The Pd/MWNTs gas-diffusion cathode can not only reductively dechlorinate 4-chlorophenols by feeding hydrogen gas,but also accelerate the two-electron reduction of O2 to H2O2 by feeding air.Therefore,the removal efficiency and the average removal efficiency of 4-chlorophenol in terms of total organic carbon（TOC） reached about 86.9% and 71.6% after 140 min electrolysis,respectively.