Enhanced Activity of Gold-Supported Cobalt Oxide for the Electrochemical Evolution of Oxygen
Enhanced Activity of Gold-Supported Cobalt Oxide for the Electrochemical Evolution of Oxygen
复制标题
DOI：
10.1021/ja200559j
复制
发表时间：
2011-04-13
影响因子：
15
通讯作者：
Bell, Alexis T.
中科院分区：
文献类型：
--
作者：
Yeo, Boon Siang;Bell, Alexis T.
采用扫描电子显微镜、线性扫描伏安法、计时电流法和原位表面增强拉曼光谱研究了在Au等金属基底上沉积的钴氧化物薄膜的电化学析氧反应。所有实验均在0.1M KOH中进行。一个显着的发现是，周转频率钴氧化物。沉积在Pt、Pd、Cu和Co上的少量氧化钴的活性降低，因为沉积在Au上的0.4 ML的氧化钴所表现出的OER比本体的OER高40倍，其顺序为Au > Pt > Pd > Cu > Co，与基底金属的电负性降低平行。另一个值得注意的发现是，在Au上沉积的0.4 ML的氧化钴的OER转换频率比体Ir的OER转换频率高近3倍。拉曼光谱显示，沉积的氧化钴以Co（3）O（4）的形式存在，但随着阳极电位的增加而逐渐氧化为CoO（OH）。沉积在Au上的氧化钴的更高的OER活性归因于作为Co（IV）阳离子存在的Co位点的分数的增加，Co（IV）阳离子的状态被认为是OER发生所必需的。提出并讨论了Co（IV）阳离子如何影响OER的假设。
Scanning electron microscopy, linear sweep voltammetry, chronoamperometry, and in situ surface-enhanced Raman spectroscopy were used to investigate the electrochemical oxygen evolution reaction (OER) occurring on cobalt oxide films deposited on Au and other metal substrates. All experiments were carried out in 0.1 M KOH. A remarkable finding is that the turnover frequency cobalt oxide. The activity of small amounts of cobalt oxide deposited on Pt, Pd, Cu, and Co decreased for the OER exhibited by similar to 0.4 ML of cobalt oxide deposited on Au is 40 times higher than that of bulk monotonically in the order Au > Pt > Pd > Cu > Co, paralleling the decreasing electronegativity of the substrate metal. Another notable finding is that the OER turnover frequency for similar to 0.4 ML of cobalt oxide deposited on Au is nearly three times higher than that for bulk Ir. Raman spectroscopy revealed that the as-deposited cobalt oxide is present as Co(3)O(4) but undergoes progressive oxidation to CoO(OH) with increasing anodic potential. The higher OER activity of cobalt oxide deposited on Au is attributed to an increase in fraction of the Co sites present as Co(IV) cations, a state of cobalt believed to be essential for OER to occur. A hypothesis for how Co(IV) cations contribute to OER is proposed and discussed.