In-situ FTIR-diffuse reflection study of methanol oxidation mechanisms on fuel cell anodes

The catalytic surfaces of membrane electrode assemblies in direct methanol/oxygen fuel cells were investigated in-situ by Fourier transform infrared-diffuse reflection spectroscopy. A novel, temperature controlled (90/spl deg/C), single cell fuel cell assembly with an infrared transparent window was constructed to facilitate such studies. Pt-black and Pt/Ru were studied as anode catalysts with platinum black on the cathode side. The vibrational modes observed on the surface of the methanol anodes include those of formaldehyde and formic acid. CO is the primary intermediate of methanol oxidation on Pt-black and Pt-Ru anode catalysts. The intensity of CO adsorption modes on Pt-Ru is less than on Pt-black. Formaldehyde oxidation on Pt-black produces more CO intermediate in comparison with formic acid oxidation. Possible mechanisms for methanol, formaldehyde, and formic acid oxidation on the anode surfaces are discussed.