Ins situ Fourier transform infrared-diffuse reflection spectroscopy of direct methanol fuel cell anodes and cathodes

In situ Fourier transform infrared-diffuse reflection spectroscopy (FTIR-DRS) was used to study both the adsorbed and desorbed species produced on high surface area anodes and cathodes of direct methanol/oxygen fuel cells. We investigated platinum-ruthenium and platinum black as anodes. The cathodes studied were platinum black. The primary product detected on both Pt-black and Pt-Ru anodes at low methanol/water vapor ratios (P-methanol: 15.2 kPa) was CO2. Consistent with previous work, CO adsorption is more prevalent on Pt-black than on Pt-Ru. In addition to CO and CO2, vibrational modes due to formic acid, methylformate, and formaldehyde are detected by FTIR-DRS under potentiostatic control. At higher methanol/water vapor ratios (P-methanol: 38.0 kPa) and low potentials (0.10 to 0.50 V), formaldehyde is the; only product at the Pt-Ru anode. Methylformate and formic acid vibrational modes appear at potentials from 0.60 to 0.80 V. CO2 and methanol are observed at open circuit on the cathode side as a result of methanol permeation from the anode to the cathode region. CO2 increases in the cathode region with increasing anode potential.