Water Oxidation and Oxygen Monitoring by Cobalt-Modified Fluorine-Doped Tin Oxide Electrodes

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• 作者：Caleb A. Kent ; Javier J. Concepcion ; Christopher J. Dares ; Daniel A. Torelli ; Adam J. Rieth ; Andrew S. Miller ; Paul G. Hoertz ; Thomas J. Meyer
• 刊名：The Journal of the American Chemical Society
• 出版年：2013
• 出版时间：June 12, 2013
• 年：2013
• 卷：135
• 期：23
• 页码：8432-8435
• 全文大小：258K
• 年卷期：v.135,no.23(June 12, 2013)
• ISSN：1520-5126

文摘

Electrocatalytic water oxidation occurs at fluoride-doped tin oxide (FTO) electrodes that have been surface-modified by addition of Co(II). On the basis of X-ray photoelectron spectroscopy and transmission electron microscopy measurements, the active surface site appears to be a single site or small-molecule assembly bound as Co(II), with no evidence for cobalt oxide film or cluster formation. On the basis of cyclic voltammetry measurements, surface-bound Co(II) undergoes a pH-dependent 1e^{鈥?/sup>/1H+ oxidation to Co(III), which is followed by pH-dependent catalytic water oxidation. O₂ reduction at FTO occurs at 鈭?.33 V vs NHE, allowing for in situ detection of oxygen as it is formed by water oxidation on the surface. Controlled-potential electrolysis at 1.61 V vs NHE at pH 7.2 resulted in sustained water oxidation catalysis at a current density of 0.16 mA/cm2 with 29鈥?00 turnovers per site over an electrolysis period of 2 h. The turnover frequency for oxygen production per Co site was 4 s鈥? at an overpotential of 800 mV at pH 7.2. Initial experiments with Co(II) on a mesoporous, high-surface-area nanoFTO electrode increased the current density by a factor of 5.}