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Title: Electrocatalytic Oxidation of Alkaline Methanol on Some Noble Metal Coated Electrodes
Authors: Guha, Prabir K
Bhattacharya, Abhijit
Kundu, Kiron K
Issue Date: Apr-1989
Publisher: NISCAIR-CSIR, India
Abstract: Anodic oxidation fo alkaline methanol has been studied on Pt and C electrodes coated with Pt, Pd, Rh, Ru, Ir andlor Au. Galvanostatic steady-state and linear sweep cyclic voltammetric methods in conjunction with chronopotentiometric and scanning electron microscopic techniques have been employed for such studies. The exchange current densities [(io)app and (io)tr] and peak current densities (ip) clearly demonstrate the superior performance of Pt-coated electrodes as compared to the electrodes coated with other noble metals. Next to Pt, Rh appears to be the second best in the case of carbon substrate and Ru for platinum substrate. The order of io values is Pt > Ru > Rh ≈ Ir >Pd >Au on Pt/M and Pt >Rh >Pd >Au on C/M and that of ip: Pt > Pd » Rh ≈ Ir >Ru » Au on Pt/M and Pt $> Rh > Pd » Au > Ru ≈ Ir on C/M. C/Ru and C/r electrodes, however, undergo corrosion in alkaline medium. The Tafel slope (b) values as also the cyclic voltammograms are indicative of a similar mechanistic pathway for Pt and Pd, which is different for Rh, Ru and Ir and yet another for Au. Rationalization of these observations by correlating them to intrinsic properties, viz. % d-band character, work function, latent heat of sublimation, HM-H of the catalyst metals (M) and extrinsic properties, viz. roughness factor, size and extent of coverage of the deposits and porosity of the base substrate of the electrodes leads to the conclusion that none of the parameters could be 'singled out' as accounting for the observed catalytic activities. Rather, the activities appear to be governed by a combination of these properties whose possible optimization in Pt results in the highest electrocatalytic activity of this metal.
Page(s): 267-275
ISSN: 0975-0975(Online); 0376-4710(Print)
Appears in Collections:IJC-A Vol.28A(04) [April 1989]

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