Electrochimica Acta 46 (2001) 3525 – 3534 Anodic oxidation of methane at noble metal electrodes: an ‘in situ’ surface enhanced infrared spectroelectrochemical study F. Hahn *, C.A. Melendres 1,2 Catalyse en Chimie Organique, Equipe Electrocatalyse, Uniersite ´ de Poitiers, UMR-CNRS n 6503, 40, Aenue du Recteur Pineau, 86022 Poitiers Cedex, France Received 28 February 2001; received in revised form 6 June 2001 Abstract The mechanism of electrooxidation of methane at 25 °C in 0.5 M HClO 4 on the noble metal electrodes Pt, Au, Pd, Ru and Rh has been investigated by ‘in situ’ infrared spectroscopy. The final product of oxidation was found to be CO 2 in all cases. Using the technique of surface enhanced infrared absorption spectroscopy and deuterated water solutions, it has been possible to detect the presence of adsorbed intermediates such as CO and CHO (or COOH) for the first time. The infrared signal enhancement observed could be accounted for by considering the increase in the surface area of the electrodeposited metals as indicated by the cyclic voltammograms. Pt and Ru appear to have the highest, and Au the lowest, electrocatalytic activity among the metals studied. © 2001 Elsevier Science Ltd. All rights reserved. Keywords: Methane; Noble metals; Anodic oxidation; Spectroelectrochemical study; Surface enhanced infrared spectroscopy www.elsevier.com/locate/electacta 1. Introduction The need for new power sources which minimize environmental pollution has spurred a renaissance in the further development of fuel cells for electric vehicle propulsion and for electricity generating power stations [1]. Fuel cell devices have proven their utility in aerospace applications where hydrogen has been used as fuel. However, problems with the storage of hydro- gen in tanks or as metal hydrides, as well as costs, have prevented the commercial use of fuel cells for other more widespread applications. Methane and methanol are among the most simple and readily available or- ganic compounds that can be used as fuel and are hence of great interest for use in fuel cell devices. Methanol is attractive because it can be obtained from renewable sources, such as corn and other agricultural products. Its electrochemical oxidation has therefore been exten- sively studied [2,3]. Little work has been done on methane as a fuel cell feedstock. Recent discovery of methane hydrate deposits under the ocean floor and the Arctic permafrost suggests that they are a potentially enormous resource that could fuel the 21st century and the third millennium [4]. There is thus a great economic incentive to develop a fuel cell device that could effec- tively utilize methane. So far, because of its high stability, the use of meth- ane as fuel has been limited to high temperature fuel cells, i.e. molten carbonate and solid oxide [5], after reforming into hydrogen and carbon monoxide mix- * Corresponding author. Tel.: +33-549-453971; fax: +33- 549-453580. E-mail addresses: francoise.hahn@univ-poitiers.fr (F. Hahn), camelendres@hotmail.com (C.A. Melendres). 1 ISE member. 2 On sabbatical leave of absence from Argonne National Laboratory, Argonne, IL 60439, USA. 0013-4686/01/$ - see front matter © 2001 Elsevier Science Ltd. All rights reserved. PII:S0013-4686(01)00649-1