2,2’-二氨基苯氧基二硫化物的电极过程动力学研究

利用循环伏安法、线性伏安法及旋转圆盘电极技术，研究了2,2’-二氨基苯氧基二硫化物(DAPOD)在含有0.1 mol•L－1 LiClO4电解质的乙腈/四氢呋喃有机溶液中，铂、金、玻碳及石墨电极上的电化学行为.伏安结果表明DAPOD中的二硫键与硫巯基之间的氧化还原反应属动力学不可逆过程，这种在室温下表现出的电化学反应不可逆性是有机二硫化物普遍存在的不足，必须通过分子内或分子间的电催化来改善其可逆性能.旋转圆盘电极测试结果显示， DAPOD的阴极还原反应级数为0.5，阳极氧化反应级数为1.由此推知DAPOD电还原属两电子转移反应，分两步完成：第一步为平衡的化学反应步骤；第二步为电子转移步骤，属决速步.同时还测定了DAPOD的阴极与阳极传递系数、交换电流、平衡电势及标准速率常数等相关的动力学常数.通过比较铂、金、玻碳及石墨四种不同材料电极对DAPOD的电极过程的影响,发现石墨对DAPOD的还原过程具有电催化作用.

Electrode Kinetics of 2,2’-diaminophenyloxydisulfide

A novel organic disulfide, 2,2’-diaminophenyloxydisulfide(DAPOD), has been proposed as a material of energy storage. The electrochemical study of this disulfide-thiolate redox couple has been studied on platinum, gold, glassy carbon or graphite electrode in AN/THF solution containing DAPOD and LiClO4 supporting electrolytes by potential cyclic sweep voltammetry, potential linear sweep voltammetry and rotating disk electrode technique. The CV results imply that the redox reactions of DAPOD are chemically reversible, yet kinetically hindered. The slow electrode kinetics indicates that the introduction of electrocatalysis to assist the electrode reaction may be effective in providing better performance. The observed reaction orders for DAPOD are 0.5 in the cathodic direction and 1 in the anodic direction. These results show that two electrons are involved in redox reaction of DAPOD, and that the reduction of the organodisulfide to the corresponding thiolate anions proceeds in two steps: the first step, chemical reaction, is at equilibrium, while the second step, charge-transfer reaction, is rate determining step. The kinetic constants such as transfer coefficients, exchange current, equilibrium potential and standard rate constant were determined. The electrochemical behavior of DAPOD at different electrode materials indicates that the graphite electrode demonstrates the electrocatalytic action to the electrode kinetics of DAPOD.