化学
电化学
电解质
无机化学
高氯酸盐
超氧化物
氯化物
循环伏安法
电子转移
红外光谱学
分析化学(期刊)
光化学
电极
物理化学
离子
有机化学
酶
作者
Simantini Nayak,P. Ulrich Biedermann,M. Stratmann,Andreas Erbe
标识
DOI:10.1016/j.electacta.2013.05.133
摘要
For an understanding of the four electron transfer mechanism of the electrochemical oxygen reduction reaction (ORR), a direct detection of intermediates on well-defined working electrode surfaces is crucial, as it bridges the gap between electrochemistry and computation. Here, the ORR is studied on the crystalline semiconductor n-Ge(1 0 0) by electrochemical attenuated total reflection infrared (ATR-IR) spectroscopy in aqueous NaClO4 and NaCl solutions at pH 10.5. Germanium-bound superoxide at a tilt angle of ∼45° with respect to the surface normal is found as an intermediate in both electrolytes. The frequency of the superoxide OO stretching mode differs by 25 cm−1 between the two electrolytes, hinting at a complex formation between at least one of the anions and the superoxo-intermediate. This complex formation may be related to the different surface terminations of germanium in the two electrolytes. The surface concentration of the superoxide intermediate is proportional to the ORR current. Analysis of the relation between absorbance and current shows that the rate constant of the second electron transfer step in the ORR, i.e. the step from superoxide to peroxide, in NaCl is three times as high as in NaClO4.
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