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

Journal Article · Wed Jun 12 00:00:00 EDT 2013 · Journal of the American Chemical Society

DOI:https://doi.org/10.1021/ja400616a· OSTI ID:1211165

Kent, CA; Concepcion, JJ; Dares, CJ; Torelli, DA; Rieth, AJ; Miller, AS; Hoertz, PG; Meyer, TJ

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(-)/1H(+) oxidation to Co(III), which is followed by pH-dependent catalytic water oxidation. O-2 reduction at FTO occurs at -0.33 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/cm(2) with 29 000 turnovers per site over an electrolysis period of 2 h. The turnover frequency for oxygen production per Co site was 4 s(-1) 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 similar to 5

• Sponsoring Organization: USDOE Advanced Research Projects Agency - Energy (ARPA-E)
• DOE Contract Number: DE-AR0000140
• OSTI ID: 1211165
• Journal Information: Journal of the American Chemical Society, Vol. 135, Issue 23; ISSN 0002-7863
• Country of Publication: United States
• Language: English