PtRu supported on mesoporous carbon as anode catalyst for direct methanol fuel cell (DMFC): Electrochemical impedance analysis of mass transport

Abstract

The performance of membrane electrode assembly (MEA) prepared with PtRu nanoparticles supported on a mesoporous carbon as anode catalyst are presented and compared against PtRu synthesized over Vulcan carbon. Polarization and power curves were obtained using 1 M methanol aqueous solution at the anode and O2 at the cathode. The mesoporous carbon supported catalyst shows peak power of 40 mW cm 2 and 67 mW cm 2 at 30 C and 60 C respectively, that is, 15e30% higher than the Vulcan supported catalyst, and exhibits a wider range of operating current. Moreover, an improvement in the mass transport is observed for the catalyst supported on mesoporous carbon, yielding a lower voltage drop at high current density. This behavior was confirmed by electrochemical impedance spectroscopy (EIS), where an increases of the Warburg coefficient value by a factor 3e4 for the catalyst supported on mesoporous carbon as compared with that supported on Vulcan, would indicate a more facile diffusion of methanol through the mesoporous carbon.