Efficient electrochemical oxidation of ethanol to carbon dioxide in a fuel cell at ambient temperature

A carbon dioxide monitor has been used to follow the Faradaic yield of CO₂ from the oxidation of ethanol vapour in a direct ethanol PEM fuel cell at ambient temperature. The time resolution of the CO₂ measurements (ca.15 s at half height for a burst of CO₂) was sufficient to observe stripping of adsorbed CO from the anode, and to monitor CO₂ yields as a function of time during linear sweep and pulse experiments. It has been demonstrated that CO₂ yields can be increased dramatically by pulsing the potential or current such that adsorbed CO is stripped from the electrode and then ethanol is allowed to readsorb. Yields of CO₂ as high as 80% have been sustained for as long as 50 s under current pulsing conditions. An average CO₂ yield of 45% was obtained during 600 s of pulsing the current between 0 and 4 mA cm⁻² at 1 Hz.