IONIC INTERACTIONS AND CHARGE-TRANSPORT PROPERTIES OF METALLOPOLYMER FILMS ON ELECTRODES
IONIC INTERACTIONS AND CHARGE-TRANSPORT PROPERTIES OF METALLOPOLYMER FILMS ON ELECTRODES
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DOI：
10.1021/la00023a065
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发表时间：
1994-11-01
期刊：
影响因子：
3.9
通讯作者：
VOS, JG
中科院分区：
文献类型：
--
作者：
FORSTER, RJ;VOS, JG
研究了支持电解质浓度、氧化还原中心负载量和温度对[Os（bpy）（2）（PVI）（n）Cl]（+）膜电化学响应的影响，其中bpy为2，2 '-联吡啶，PVI为聚（N-乙烯基咪唑）.这些修饰电极的循环伏安法，计时电流法和采样电流响应在含对甲苯磺酸（pTSA）的溶液中是非常理想的。在0.1-1.0 M的范围内的电解质浓度的电池电阻的依赖性表明，该膜含有相当大量的电解质和水，和唐南排除已经失败。形式电位对pTSA浓度的依赖性表明，对于高氧化还原位点负载，氧化还原对的还原和氧化形式都是离子配对的，而对于较低负载，只有氧化形式是离子配对的。这与界面电容的测量结果一致，表明在高氧化还原位点负载下聚合物膜内的有效介电常数较低。氧化还原对的还原和氧化形式之间的顺序的差异已被探测从形式电位的温度依赖性。这些数据表明，固定化的氧化还原中心的局部微环境变得类似于在高支持电解质浓度的水溶液中发现的。已使用循环伏安法和计时电流法评估电荷传输D-CT的表观扩散系数。这两种技术给出的DCT值在实验误差内无法区分。与Dahms-Ruff理论一致，电荷传输速率线性依赖于锇氧化还原位点浓度。这些数据，连同低膜电阻，和D-CT对支持电解质浓度的依赖性，表明电子跳跃是这些系统的限速步骤。自交换速率常数为（6.0 +/-0.3）× 10（5）M（-1）s（-1），与支持电解质浓度无关。
The effects of supporting electrolyte concentration, redox site loading, and temperature on the electrochemical response of [Os(bpy)(2)(PVI)(n)Cl](+) films, where bpy is 2,2'-dipyridyl and PVI is poly(N-vinylimidazole), are investigated. The cyclic voltammetric, chronoamperometric, and sampled current responses of these modified electrodes are unusually ideal in p-toluenesulfonic acid (pTSA) containing solutions. The dependence of the cell resistance on electrolyte concentration over the range 0.1-1.0 M suggests that the films contain rather large amounts of electrolyte and water, and that Donnan exclusion has failed. The dependence of the formal potential on pTSA concentration suggests that, for high redox site loadings, both the reduced and oxidized forms of the redox couple are ion-paired, while for lower loadings only the oxidized form is ion-paired. This is consistent with measurements of the interfacial capacitance that suggest a lower effective dielectric constant within the polymer film at high redox site loading. The difference in ordering between the reduced and oxidized forms of the redox couples has been probed from the temperature dependence of the formal potential. These data reveal that the local microenvironment of the immobilized redox centers becomes similar to that found in aqueous solution at high supporting electrolyte concentrations. The apparent diffusion coefficient for charge transport D-CT has been evaluated using cyclic voltammetry and chronoamperometry. These two techniques give values of DCT that are indistinguishable within experimental error. In agreement with Dahms-Ruff theory, the rate of charge transport depends linearly on the osmium redox site concentration. These data, together with the low film resistance, and the dependence of D-CT on supporting electrolyte concentration, suggest that electron hopping is the rate-limiting step for these systems. The self-exchange rate constant obtained is (6.0 +/- 0.3) x 10(5) M(-1) s(-1) and is independent of the supporting electrolyte concentration.