Franz Glaubitz, Erik Lindemann, Valentin Mirceski, Uwe Schröder
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引用次数: 0
摘要
在这项研究中,详细研究了钴(II/III)氧化氢氧化物的氧化还原行为。利用方波伏安法(SWV)增强的灵敏度和独特的脉冲特性,可以观察到两种截然不同的电极过程,提出了Co(OH)2→CoO(OH)→CoO2两步氧化Co(OH)2。在循环伏安法的初始扫描中,Co(OH)2被不可逆氧化为CoO(OH),在随后的扫描中,Co3O4/CoO(OH)氧化还原体系占主导地位。进一步对该体系进行了动力学表征。理论研究和独特的SWV峰分裂表明,电极反应的阳极电荷转移系数为0.59,表观标准速率常数为ks,app=(2.9±0.1)⋅10−5 cm s−1。针对氧化还原对Co3O4/CoO(OH)电极过程的复杂性,采用了最新引进的多频电化学法拉第光谱(MEFS)技术。与方波法和循环伏安法的多个小时实验相比,MEFS的快速测量时间仅为4 s,表观标准速率常数为ks,app=(2.2±0.2)⋅10−5 cm s−1,与现有方法非常接近,突出了这种新型方波衍生技术的优势。
Kinetic and Mechanistic Investigation of Cobalt Oxide Hydroxide Thin Films by Square-Wave Voltammetry and Multi-Frequency Electrochemical Faradaic Spectroscopy
In this study, a detailed investigation of the redox behavior of cobalt(II/III) oxide-hydroxide is presented. With the enhanced sensitivity and unique pulse nature of square-wave voltammetry (SWV), two distinct electrode processes could be observed, proposing a two-step oxidation of Co(OH)2 according to: Co(OH)2→CoO(OH)→CoO2. In the initial scan of cyclic voltammetry, Co(OH)2 is irreversibly oxidized to CoO(OH) with the quasireversible Co3O4/CoO(OH) redox system prevailing in subsequent scans. The system was further kinetically characterized. Theoretical studies and the unique peak splitting in SWV revealed that the electrode reaction is associated with an anodic charge transfer coefficient of
=0.59 and an apparent standard rate constant of ks,app=(2.9±0.1) ⋅ 10−5 cm s−1. To cope with the complexity of the electrode process pertinent to the redox couple Co3O4/CoO(OH), the recently introduced and advanced multi-frequency electrochemical Faradaic spectroscopy (MEFS) was applied. With rapid measurement times of only 4 s, compared to multiple, hour-long experiments for square-wave and cyclic voltammetry, an apparent standard rate constant of ks,app=(2.2±0.2) ⋅ 10−5 cm s−1 was obtained with MEFS, which is quite close to the established methods, highlighting the advantages of this novel square-wave derived technique.
期刊介绍:
ChemElectroChem is aimed to become a top-ranking electrochemistry journal for primary research papers and critical secondary information from authors across the world. The journal covers the entire scope of pure and applied electrochemistry, the latter encompassing (among others) energy applications, electrochemistry at interfaces (including surfaces), photoelectrochemistry and bioelectrochemistry.