期刊
ELECTROANALYSIS
卷 17, 期 11, 页码 947-952出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/elan.200403200
关键词
iridium; anodic oxidation indifferent electrolytes; metal-oxide electrode; Ir/Ir(OH)(3); Ir/IrO2; nH(2)O
Iridium oxide films (IROFs) are known to have an enhanced or the so-called super-Nernstian (< 59 mV/pH) pH-sensitivity. The intention in the present study was to find out the reasons of such behavior and also to elucidate the nature of iridium anodic oxidation processes. The methods employed were combined cyclic voltammetry and chronopotentiometry. Iridium layers of 0.1 to 0.2 mu m thickness, deposited thermally on titanium or gold-plated titanium substrates, were used for investigations. IROFs on the surface of working electrodes were formed anodically by applying a constant potential in deaerated and oxygen-containing solutions of 0.5 M H2SO4, 0.1 M KOH and 0.5 M H3PO4 +KOH. Linear pH-dependences of the stationary open-circuit potential with the slopes close to 59 mV/pH were found for iridium electrode oxidized at 0.4 V - 0.8 V (RHE) in deaerated and at 0.8 V - 1.2 V (RHE) in 0,containing solutions. They were attributed to reversible Ir/lr(OH)(3) and Ir/ lrO(2) center dot nH(2)O metal-oxide electrodes, respectively. It has been suggested that the main current peaks seen in the voltammograms of iridium electrode in acid and alkaline solutions are of different nature. The difference between iridium electrode surface states in acid and alkaline solutions has been presumed to be the main reason of super-Nernstian pH-sensitivity of the IROFs. On the basis of the results obtained standard potential of Ir/lr(OH)3 electrode and the solubility product of Ir(OH)3 have been evaluated: E degrees(Ir/(OH)), = 0.78 +/- 0.02 V and K-sp = 3.3 x 10(-64).
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据