The purpose of the work reported here is to give carbon black with a high functional surface, especially for use in fuel cell oxygen electrodes. The authors have investigated the surface properties, such as wettability, rate constant of H2O2 decomposition, and surface functional groups, of surface modified carbon black by low temperature oxygen plasma. This work also describes the relationships between the surface properties and the electrochemical behavior in an aqueous KOH solution of the fuel cell oxygen electrodes with oxygen plasma modified carbon black. The results are as follows: The carbon black surface has changed from hydrophobic to hydrophilic with the plasma processing. The plasma processing has enhanced the H2O2 decomposition ability of carbon black. These results can be explain by the increase of functional groups containing oxygen such as >C=O, –COOH etc. on the carbon black surface. The polarization behavior of a fuel cell oxygen electrode with carbon black has been much improved by the plasma processing. It can be attributed to the formation of the stable three phase zone owing to the moderate wettability, high H2O2 decomposition ability, and development of fine pores of the carbon black electrode. From the experiment by using a rotating disk electrode, it can be concluded that oxygen electrode reaction is mainly two electrons reduction forming H2O2 as a intermediate.
