Water Oxidation Using a Cobalt Monolayer Prepared by Underpotential Deposition

• Published in: Langmuir Vol. 29; no. 47; pp. 14728 - 14732
• Main Authors: Marsh, David A, Yan, Wenbo, Liu, Yu, Hemminger, John C, Penner, Reginald M, Borovik, A.S
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 26.11.2013
• Subjects: atomic force microscopy; Catalysis; catalysts; catalytic activity; Chemistry; cobalt; Electrochemistry; electrodes; Exact sciences and technology; General and physical chemistry; gold; ions; Kinetics and mechanism of reactions; ligands; oxidation; oxygen; surface area; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; uncertainty; X-ray diffraction; X-ray photoelectron spectroscopy; Water; Atomic force microscopy; Gold; Uncertainty; Catalytic reaction; Grazing incidence; Ions; Transition metal; Cobalt; Conversion; X ray diffraction; Electrodes; Electrocatalysis; Efficiency; Photoelectron spectrometry; Oxidation; Catalysis; Surface area; Surface activity; Current density; Catalyst; Deposition
• ISSN: 0743-7463; 1520-5827; 1520-5827
• DOI: 10.1021/la403038e

Development of electrocatalysts for the conversion of water to dioxygen is important in a variety of chemical applications. Despite much research in this field, there are still several fundamental issues about the electrocatalysts that need to be resolved. Two such problems are that the catalyst mass loading on the electrode is subject to large uncertainties and the wetted surface area of the catalyst is often unknown and difficult to determine. To address these topics, a cobalt monolayer was prepared on a gold electrode by underpotential deposition and used to probe its efficiency for the oxidation of water. This electrocatalyst was characterized by atomic force microscopy, grazing-incidence X-ray diffraction, and X-ray photoelectron spectroscopy at various potentials to determine if changes occur on the surface during catalysis. An enhancement of current was observed upon addition of PO4 3– ions, suggesting an effect from surface-bound ligands on the efficiency of water oxidation. At 500 mV overpotential, current densities of 0.20, 0.74, and 2.4 mA/cm2 for gold, cobalt, and cobalt in PO4 3– were observed. This approach thus provided electrocatalysts whose surface areas and activity can be accurately determined.