Nanoscale Morphological Control of Anode Electrodes by Grafting of Methylsulfonic Acid Groups onto Platinum–Ruthenium-Supported Carbon Blacks

Abstract

An increase in catalyst utilization in direct methanol fuel cells (DMFCs) is necessary to improve performance and reduce costs. We propose an electrode fabrication method, based on the process of grafting a proton-conducting agent onto catalyst-supported carbons before the conventional electrode fabrication process where catalyst-supported carbons are simply mixed with the perfluorosulfonic ionomer. In this study, methylsulfonic acid groups as proton-conducting agents have been successfully introduced to the pores of catalyst-supported carbons. We found that the chemical connections between the grafted methylsulfonic acid groups and the surface of catalyst-supported carbons were stable up to around . Furthermore, by morphological analysis, we found that the grafted methylsulfonic acid groups were homogeneously introduced into both the primary and the secondary pores, and produced no significant structural change in the secondary pore that could affect the mass transfer process. The DMFC performance of the membrane electrode assembly (MEA) made using our grafting method was superior to that of an MEA made using the conventional method. A maximum power density of was obtained by using grafted catalyst-supported carbons at an anode electrode in the DMFC in the low loading amount of (Pt loading amount: ) at under atmospheric pressure.