Effect of Electric Current on the Wettability of Carbon-Containing Gas Diffusion Electrodes by Aqueous Solutions and the Change in Their Capacitance Characteristics

Abstract

We study the effect of the treatment by an electric current of two-layer gas diffusion electrodes made of porous (66–68 vol %) composite material based on A-437E acetylene black and polytetrafluoroethylene. Polarization is carried out cyclically in the range 0.0 ± 2.0 V by anodic and cathodic currents, respectively, in 1 M H₂SO₄ and 0.5 M KOH with the addition of tetrabutylammonium bromide (TBAB). In both cases, the increase in the charge passed leads to an increase in the volume of electrolyte pores and the electrical capacitance of the electrodes. Under anodic polarization, the increase in the wettability and capacitance of the electrodes is larger than under the cathodic process; however, in the latter case, the carbon surface does not undergo oxidation. As the charge passed and the TBAB concentration increases, the ohmic loss grows. The possible causes of the observed phenomena are considered.