Preparation of cathode catalysts for PEMFC by carbon-alloying techniques

Abstract

Development of cathode catalysts with lower platinum content or without platinum is an urgent issue for the commercialization of proton-exchange membrane fuel cell (PEMFC). Our idea to deal with the issue is to develop active carbonbased catalysts for the oxygen reduction by employing carbon-alloying techniques. In the first section of the present paper, the idea of carbon-alloy based catalysts will be explained. In the second and the third sections, the oxygen reduction activity, the structure, and the chemical nature of the two types of carbon alloys are given, i.e. metal-alloyed carbons and N-or BN-alloyed carbons. The importance of the surface defects on the shell-like structure and the N atoms located on the edge of graphene are pointed out for providing oxygen reduction activities to carbon materials. In the fourth section, we clarified that the oxygen reduction on the carbon-alloys included direct four-electron mechanism by employing different two electrochemical techniques. Lastly, preliminary results of single cell tests are described with a cobalt phthalocyaninealloyed carbon, which could give a maximum power of 0.2Wcm-2 without platinum.