In situ 50°C FTIR spectroscopy of Pt and PtRu direct methanol fuel cell membrane electrode assembly anodes

A tandem surface-transmission Fourier transform infrared (FTIR) method permits the simultaneous investigation of adsorbed and desorbed species formed at the electrode surface of direct methanol fuel cell (DMFC) membrane electrode assemblies (MEAs). Potential dependent, in situ specular reflectance spectra and on-line transmission FTIR spectroscopy of adsorbed and desorbed species on working fuel cell electrode surfaces, confirm that linear bound CO, the primary intermediate on unsupported Pt and PtRu surfaces of fuel cell MEAs, have lower Stark tuning rates than the corresponding on arc-melted alloys. Two peaks corresponding to CO stretching modes were observed on a PtRu fuel cell anode surface prepared with Johnson Matthey catalysts. The higher frequency peak is ascribed to a Pt-rich alloy and the low frequency peak is ascribed to either pure Ru or an Ru-rich phase. The tandem technique confirms that a peak easily misassigned as a linear bound CO stretching mode (2083 cm(-1)) is a methanol overtone peak. In addition to CO2, methylformate is a major product of a gas fed DMFC, which is detected at the anode exhaust by on-line FTIR. (C) 2002 The Electrochemical Society.