Innovative electrodes for direct methanol fuel cells based on carbon nanofibers and bimetallic PtAu nanocatalysts

Direct methanol fuel cells are very promising power sources, but the easy poisoning of the platinum anode electrocatalyst by CO-like reaction intermediates, restricts their industrial application and commercialization. The development of Pt-based alloys or bimetallic catalysts, in which the second metal acts as Pt poisoning inhibitor, is one of the main promising solutions to this problem. In this work we have combined the use of unconventional methods to deposit the catalyst nanoparticles with unconventional carbon supports. Innovative electrodes made of platelet carbon nanofibers, directly grown on graphite paper, as substrate for electrodeposited platinum and gold bimetallic nanoparticles, have been developed. These electrodes allow having a single layer with both the diffusive and catalytic function, and a considerable decrease of noble metals amount (about five times), with consequent large cost reduction. Moreover, the replacement of the conventional ink deposition methods with electrodeposition for platinum and gold dispersion, considerably increases the catalytic activity. The electrocatalytic performance results were encouraging. Gold allows increasing the catalyst poisoning tolerance and then the electrode long term stability. The innovative electrodes show a performance improvement up to three times compared to a commercial carbon substrate electrode (Vulcan XC-72R) with ink-spray deposited PtRu nanoparticles as catalyst.