Electrooxidation of ethylene glycol on a carbon-supported Pt catalyst at elevated temperatures and pressure: A high-temperature/high-pressure DEMS study

The electrooxidation of ethylene glycol (EG) on a Pt/Vulcan catalyst was investigated over a wide range of temperatures (20–100 °C) at 3 bar overpressure and under continuous electrolyte flow by on-line differential electrochemical mass spectrometry (DEMS). Both Faradaic current and the ion current for CO2 formation were continuously followed during potentiodynamic and potentiostatic measurements. They show pronounced temperature and potential effects on the total reaction rates and on the rate/selectivity for complete oxidation to CO2. While at room temperature formation of incomplete C2 oxidation products prevails, complete oxidation to CO2 becomes increasingly important at higher temperatures and at lower potentials (50% current efficiency for CO2 formation at 100 °C and 0.5 V). This behavior is reflected by a significantly higher barrier for CO2 formation than for the total reaction, with values of 80 and 50 kJ mol−1, respectively, at 0.5 V. The implications of these data for the understanding and proper description of the reaction in fuel cell applications and the importance of realistic reaction conditions in model studies for predictions of the reaction behavior under these conditions are discussed.