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Electrocatalysis by nanoparticles: Optimization of the loading level and operating pH for the oxygen evolution at crystallographically oriented manganese oxide nanorods modified electrodes

Mohammad, Ahmad M. and Awad, Mohamed I. and El-Deab, Mohamed S. and Okajima, Takeyoshi and Ohsaka, Takeo (2008) Electrocatalysis by nanoparticles: Optimization of the loading level and operating pH for the oxygen evolution at crystallographically oriented manganese oxide nanorods modified electrodes. Electrochimica Acta, 53 (13). 4351 - 4358.

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Official URL: http://www.sciencedirect.com/science/article/B6TG0...

Abstract

The electrocatalytic evolution of oxygen gas is investigated at manganese oxide nanorods (nano-MnOx) modified Au, Pt and GC electrodes in a wide range of pH values, ranging from highly acidic to highly basic. Morphological investigation has been carried out by a scanning electron microscopy (SEM), which revealed the deposition of nano-MnOx in a nanorod morphology. A significant enhancement of the electrocatalytic activity of the Au, Pt and GC electrodes towards the oxygen evolution reaction (OER) was observed upon the electrodeposition of nano-MnOx onto the aforementioned electrodes. The effect of the surface coverage of the manganese oxide and the pH of the electrolyte was investigated to seek an optimization. The highest cathodic shift in the onset potential of the OER was obtained in 0.5 M KOH irrespective of the substrate whereas the optimum loading (surface coverage) was about ca. 52%. The origin of the enhancement of the OER is addressed with the assistance of an X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) techniques. The preferential electrodeposition of crystallographically oriented nano-MnOx (in the manganite phase, γ-MnOOH) is thought to play the primary role in the observed enhancement.

Item Type:Article
Uncontrolled Keywords:H2-O2 fuel cells
Subjects:Technology > Nanotechnology and energy applications
Material Science > Nanostructured materials
ID Code:3999
Deposited By:SPI
Deposited On:30 Mar 2009 18:00
Last Modified:30 Mar 2009 18:00

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