Electrochemical corrosion of a glassy carbon electrode
Electrochemical corrosion of a glassy carbon electrode
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DOI：
10.1016/j.cattod.2017.07.013
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发表时间：
2017-10-15
期刊：
影响因子：
5.3
通讯作者：
Schloegl, Robert
中科院分区：
文献类型：
--
作者：
Yi, Youngmi;Weinberg, Gisela;Schloegl, Robert
玻璃碳具有耐高温、硬度高、密度小、电阻低等特点，在电化学领域有着广泛的应用。本研究的重点是电化学氧化条件下的化学电阻，这发生在氧气参与的反应，如氧还原反应（ORR）和析氧反应（OER）。研究了玻璃碳在碱性、中性和酸性介质中的电化学行为，结果表明，在不同的腐蚀介质中，玻璃碳的电化学腐蚀过程具有相同的化学过程，但其腐蚀机理不同，拉曼、红外（IR）和X射线光电子能谱（XPS）等光谱分析表明，玻璃碳在不同介质中腐蚀的电化学特征与氧官能团的形成有直接的关系。用显微镜观察了碳氧化引起的碳表面形貌变化。在酸性条件下，电极表面粗糙，而在碱性条件下，电极表面出现凹陷，推测电极在酸性条件下的降解是由于酸催化氧化形成表面氧化物，导致石墨结构开环，从而导致本体氧化。在碱性介质中，OH自由基优先与烷基位点链反应，导致碳层边缘氧化，直到它们变得亲水并溶解。
Glassy carbon is widely used in electrochemistry due to its properties of high temperature resistance, hardness, low density and low electrical resistance. The present study focuses on the chemical resistance under electrochemical oxidative conditions, which occur under oxygen-involving reactions like oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The electrochemical performance of glassy carbon investigated in alkaline, neutral and acidic media reveal the same chemical processes during the OER but showing different degradation mechanism.The electrochemical signature of the corrosion in different media could be directly associated with the formation of oxygen functional groups determined by spectroscopic methods like Raman, infrared (IR) and x-ray photoelectron spectroscopy (XPS). The morphology change of the carbon surface caused by carbon oxidation was investigated by microscopy. A rough surface was obtained in the acidic case, whereas dents were seen in alkaline media.It is assumed that the glassy carbon electrode in acidic media degrades by forming surface oxides by acid catalyzed process leading to ring opening in the graphitic structure and therefore oxidation in the bulk. In alkaline media OH radicals preferentially react with alkyl site chains, leading to oxidation of the edges of carbon layers until they become hydrophilic and dissolve.