Investigation of bimetallic Pt–M/C as DMFC cathode catalysts

A low temperature preparation procedure, based on a combination of colloidal and incipient wetness methods, was developed to modify the Pt catalyst with transition metals (Fe, Cu and Co). A moderate degree of alloying was obtained with Pt–Fe/C and Pt–Co/C cathode catalysts by using the new low temperature preparation route; whereas, a high degree of alloying was obtained for Pt–Cu/C by using the same procedure. Despite of the high metal concentration (60 wt%) on carbon, all catalysts showed small primary metal particle size and a low degree of agglomeration. These catalysts were investigated as cathodes in direct methanol fuel cells (DMFCs) operating at low temperatures (60 °C). It appeared that Pt–Fe/C catalysts were superior than Pt/C, Pt–Co/C and Pt–Cu/C catalysts both in terms of catalytic activity and tolerance to methanol. Adsorbed methanolic residues stripping analysis indicated a better methanol tolerance and an enhanced activity towards oxygen reduction in the case of the Pt–Fe system. An improvement of the DMFC single cell performance was also observed in the presence of Pt–Fe catalysts.