Study of oxygen reduction reaction on carbon-supported bimetallic Pt(1-x)Crx/C electrocatalysts tolerant

to methanol in acid electrolyte

 

R.K. Koffi*, A. Trokourey

Laboratory of physical chemistry, UFR SSMT Cocody Abidjan University,

22 B.P. 582 Abidjan 22, Côte d’Ivoire.

* Corresponding author. E-mail: rogerkkoffi@yahoo.fr

Received: 11 January 2010; revised version accepted: 09 April 2010

 

Abstract

Catalysts based on platinum are widely used in low temperature fuel cells. So carbon-supported platinum metal PtM (Pt = platinum, M = transition metal) systems are generally employed as cathode electrocatalysts in direct methanol fuel cells and as methanol tolerant catalysts. Carbon-supported platinum ruthenium PtRu catalysts are used as anode catalysts and as carbon monoxide (CO) tolerant catalysts. And then bimetallic systems based on platinum with first-row transition elements are used as improved catalyst for direct methanol fuel cells cathodes. This paper presents an overview of the preparation and chemical, morphological characteristics of carbon-supported PtM catalysts. Various compositions platinum chromium catalysts supported on carbon Pt(1-x)Crx/C (x = 0; 0.1; 0.2; 0.3; 0.4) are prepared by following a simultaneous chemical reduction way. Energy dispersive X-rays is used to determine the elementary composition and Transmission electron microscopy pictures show that particles size of the catalyst increases slightly with the increase of the chromium fraction. Cyclic voltammetry is used to evaluate the electrochemical surface area. Rotating disk electrode cathodic curves show that Pt0.8Cr0.2/C and Pt0.7Cr0.3/C bimetallic catalysts have the highest mass activity and specific activity towards oxygen reduction reaction as compared to the platinum supported on carbon Pt/C monometallic catalyst in 0,5 M sulphuric acid (H2SO4). However, platinum chromium supported on carbon Pt0.8Cr0.2/C bimetallic system appears to be a more active catalyst for oxygen reduction reaction in 0,5 M H2SO4 + 0,1 M CH3OH.

 

Keywords: Chemical reduction; Bimetallic electrocatalysts; Platinum; Transition element; Oxygen reduction.

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