Activation of Carbon Materials by Plasma Processing and Industrial Application

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We have investigated the surface properties which are electric conductivity, wettability, surface functional groups, and rate constant of H_2O_2 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 ; the conductivity of AB decreases with processing time, the AB surface changes from hydrophobic to hydrophilic, and the processing enhances the H_2O_2 decomposition ability of AB.These facts would be explained by the increase of oxygen functionalities such as aromatic -OH,>C=O,-COOH etc.of AB surface. The polarization and discharge behavior 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 adequate wettability, high H_2O_2 decomposition ability, and developed fine pore of the AB electrode. From experiments using a rotating ring disk electrode, it can be concluded that oxygen electrode reaction on AB surface is a two electron reaction forming H_2O_2 as an intermediate.