In Situ Fourier Transform Infrared‐Diffuse Reflection Spectroscopy of Direct Methanol Fuel Cell Anodes and Cathodes

Abstract

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 . Consistent with previous work, CO adsorption is more prevalent on Pt‐black than on Pt‐Ru. In addition to CO and , 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. and methanol are observed at open circuit on the cathode side as a result of methanol permeation from the anode to the cathode region. increases in the cathode region with increasing anode potential.