Evaluation of Catalytic Activity of Pt and Pt-Ru Catalysts for Electro-oxidation of Methanol in Acid Medium by Cyclic Voltammetry

A. S. A. Khan,^1* Riaz Ahmed,¹ M. Latif Mirza²

¹Fuel Cell Electrochemistry Group, Pakistan Institute of Nuclear Science and Technology, P.O. Nilore, Islamabad, Pakistan

²Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur, Pakistan

 

Received 27 July 2007; accepted 14 July 2009

 

Abstract

The cyclic voltammetric study on the electro-oxidation of methanol on 30 % Pt and 20 % Pt +10 % Ru catalysts supported on Vulcan XC-72 was carried out in 0.5 M H₂SO₄. Kinetic parameters such as exchange current density, Tafel slope and heterogeneous rate constants were calculated. The 30 % Pt showed a higher apparent catalytic activity for the electro-oxidation of methanol as compared with 20 % Pt + 10 % Ru catalyst. The presence of Ru did not contribute significantly towards the apparent catalytic activity of a catalyst for the electro-oxidation of methanol but it may be useful to prevent the catalyst from CO poisoning. Thermodynamic parameters, ΔH^*, ΔS^*, and ΔG₂₉₈^* have been evaluated. The values of ΔH^* and ΔG₂₉₈^* were positive showing that the electro-oxidation of methanol is an endothermic and non-spontaneous process.

Keywords: methanol, acid medium, cyclic voltammetry, catalytic activity, kinetics, thermodynamic

 

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^*Corresponding author. E-mail adress : abdulsattar_alikhan@email.com