Methanol and ethanol electro-oxidation on Pt-SnO2 and Pt-Ta2O5 sol-gel-modified boron-doped diamond surfaces

Author(s)

Salazar-Banda, Giancarlo R. ^{[1, 2]} ; Suffredini, Hugo B. ^[3] ; Avaca, Luis A. ^[1] ; Machado, Sergio A. S. ^[1]

Affiliation

^[1] Univ Sao Paulo, Inst Quim, BR-13560970 Sao Carlos, SP - Brazil

^[2] Univ Tiradentes, ITP, Programa Posgrad Engn Proc, BR-49032490 Aracaju, SE - Brazil

^[3] Univ Fed ABC, Ctr Ciencias Nat & Humanas, Santo Andre, SP - Brazil

• Document type: Journal article
• Source: Materials Chemistry and Physics; v. 117, n. 2-3, p. 434-442, OCT 15 2009.
• Web of Science Citations: 27

Abstract

The search for more efficient anode catalyst than platinum to be used in direct alcohol fuel cell systems is an important challenge. In this study, boron-doped diamond film surfaces were modified with Pt, Pt-SnO(2) and Pt-Ta(2)O(5) nano-crystalline deposits by the sol-gel method to study the methanol and ethanol electro-oxidation reactions in acidic medium. Electrochemical experiments carried out in steady-state conditions demonstrate that the addition of SnO(2) to Pt produces a very reactive electrocatalyst that possibly adsorbs and/or dissociate ethanol more efficiently than pure Pt changing the onset potential of the reaction by 190 mV toward less positive potentials. Furthermore, the addition of Ta(2)O(5) to Pt enhances the catalytic activity toward the methanol oxidation resulting in a negative shift of the onset potential of 170 mV. These synergic effects indicate that the addition of these co-catalysts inhibits the poisoning effect caused by strongly adsorbed intermediary species. Since the SnO(2) catalyst was more efficient for ethanol oxidation, it could probably facilitate the cleavage of the C-C bond of the adsorbed intermediate fragments of the reaction. (C) 2009 Elsevier B.V. All rights reserved. (AU)