Surface Modification of Acetylene Black by Oxygen Plasma Processing and Application to Gas Diffusion Electrode

Abstract

The authors have investigated the surface properties which are electric conductivity, wettability, surface functional groups, and rate constant of H₂O₂ decomposition of surface modified acetylene black (AB) by low temperature oxygen plasma of dc glow discharge. This work also describes the relations between the surface properties and the electrochemical behavior in an aqueous KOH solution of the gas diffusion electrodes with oxygen plasma processed AB. The results are as follows; i) the conductivity of AB decreasing with processing time. ii) the AB surface changing from hydrophobic to hydrophilic. iii)making it possible to get AB high H₂O₂ decomposition ability by the plasma processing. These facts would be illustrated by the increase of oxygen functionalities such as aromatic -OH, >C=-O, -COOH etc. of AB surface. The polarization and discharge behaviors of oxygen electrode with AB have been much improved by the plasma processing. These can be regarded as forming the stable three phase zone owing to adapt wettability, high H₂O₂ decomposition ability, and developed fine pore of the AB electrode.