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 oC). 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.