Electrochemical Oxidation of Carbon Monoxide on a Pt Electrode at Lower Potential in Hot Aqueous Solution at 423 K and 473 K

Abstract

Electrochemical oxidation of carbon monoxide between 0.3 and 0.5 V vs. RHE (reversible hydrogen electrode) was investigated in hot 0.005 M H₂SO₄–0.2 M Na₂SO₄ solution at 423 and 473 K under CO pressures ranging from 0.08 to 1.25 MPa. The reaction could be well explained by both the Langmuir–Hinshelwood mechanism for the reaction between carbon monoxide and water and the Langmuir isotherm for adsorption of carbon monoxide on a Pt electrode. Activation energy around 60 kJ·mol^–1 was observed. This value almost agrees with the apparent activation energy for electrochemical oxidation of methanol on a Pt electrode obtained between 393 and 463 K by Watanabe et al. (1997). We confirmed that CO adsorption decreases with the increase of temperature.