通过电合成前驱体Ti(OEt)4直接水解法制备纳米TiO2膜修饰电极。用循环伏安法、电位阶跃法和电解合成法研究了纳米TiO2膜电极氧化还原行为以及电催化还原邻硝基苯酚(ONP)的活性与机理。结果表明,在硫酸介质中纳米TiO2膜电极在阴极扫描时具有2对可逆氧化还原峰,对应于TiO2/Ti2O3和TiO2/Ti(OH)3这2个氧化还原电对的可逆电极过程,可逆半波电位Er1/2分别为-056V和-096V(vs.SCE,扫描速度01V/s)。在酸性介质中纳米TiO2膜修饰电极对ONP的还原具有很高的异相电催化活性,TiO2/Ti2O3电对中的TiⅣ/TiⅢ氧化还原电对作为媒质间接电还原ONP为邻氨基苯酚(OAP),反应机理为电化学偶联随后化学催化反应(EC′)机理。在50℃使用纳米TiO2膜阴极间接电还原ONP为OAP的电流效率达90%以上,产物纯度为991%。The precursor Ti(OEt) 4 prepared by anodic dissolution of metallic titanium in absolute ethanol was directly hydrolyzed by a sol gel process to give nano TiO 2 film on a titanium electrode(Ti/nano TiO 2 ). Redox behavior and electrocatalytic activity of the Ti/nano TiO 2 electrode was investigated by cyclic voltammetry, potential step chronoampermetry, and bulk electrolysis. The results indicated that there were two pairs of well defined redox peaks for Ti/nano TiO 2 film electrode in the 1 mol/L H 2 SO 4 in correspondence with TiO 2 /Ti 2 O 3 and TiO 2 /Ti(OH) 3 reversible electrode processes with E r 1/2 being-0 56 V and-0 96 V( vs .SCE), respectively, at 0.1 V/s. Ti/nano TiO 2 electrode showed a high heterogeneous electrocatalytic activitiy in acidic medium in reduction of o nitrophenol. The indirect electroreduction of o nitrophenol to o aminophenol by Ti Ⅳ /Ti Ⅲ redox pair on nano TiO 2 film surface is believed to follow chemical catalysis mechanism(EC′). In preparative electrolysis at 50 ℃ on Ti/nano TiO 2 electrode the current efficiency for o aminophenol was over 90%.安徽省自然科学基金(00045317);; 安徽省高校科研基金(2003kj141,2004kj164zd)资助项
