Concurrent oxygen reduction and methanol oxidation in sulfuric acid solutions on platinized platinum electrodes

Abstract

Steady-state polarization curves are compared in solutions of 0.5 M H2SO4 + O2 (saturated), 0.5 M H2SO4 + (0.005–0.1) M CH3OH, and 0.5 M H2SO4 + (0.005–0.1) M CH3OH + O2 (saturated) on a Pt/Pt electrode. A considerable difference is found between the currents in mixed solutions and those expected based on the principle of additivity of currents in CH3OH and O2 individual solutions. The surface coverages with the CH3OH and O2 adsorption products are determined in the potential range of 0.2–0.9 V (RHE). Open-circuit potentials are measured in mixed solutions. The obtained results suggest that the direct heterogeneous interaction between methanol and oxygen occurs alongside with faradaic reactions. This is assumed to lead to a decrease in methanol electrooxidation currents at E ≥ 0.8 V and their increase at E ≤ 0.65 V.