Fuel cells are appealing for a variety of energy needs, but the high materials and manufacturing costs have hampered their commercialization. The limited availability and the high cost of the currently used platinum catalysts, for example, pose a serious problem in their practical application. We report here non-platinum electrocatalyst systems, such as Pd-Co-Au and Pd-Ti, that are proposed from simple thermodynamic guidelines and selected by a rapid screening technique, which show electrochemical performance in proton exchange membrane fuel cells (PEMFC) similar to that found with commercial platinum catalysts. This finding opens up a new avenue to develop potentially less expensive electrocatalysts.

The catalytic activity of carbon supported Pd-Co-Mo for the oxygen reduction reaction (ORR) in a single cell proton exchange membrane fuel cell (PEMFC) has been investigated at 60 degrees C and compared with data from commercial Pt catalyst and our previously reported Pd-Co-Au and Pd-Ti catalysts. The Pd-Co-Mo catalyst with a Pd:Co:Mo atomic ratio of 70:20:10 exhibits slightly higher catalytic activity like the Pd-Co-Au catalyst than the commercial Pt catalyst, but with excellent chemical stability unlike the Pd-Co-Au catalyst. The Pd-Co-Mo catalyst also exhibits better tolerance to methanol poisoning than Pt. Investigation of the catalytic activity of the Pd-Co-Mo system with varying composition and heat treatment temperature reveals that a Pd:Co:Mo atomic ratio of 70:20:10 with a heat treatment temperature of 500 degrees C exhibits the highest catalytic activity. Although the degree of alloying increases with increasing temperature from 500 to 900 degrees C as indicated by the X-ray diffraction data, the catalytic activity decreases due to an increase in particle size and a decrease in surface area.

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Mesoporous carbons with high surface area, large pore diameter, and enhanced mesoporosity have been synthesized by a soft colloidal template route with various aniline/cetyltrimethylammonium bromide (CTABr) ratios and investigated as an electrocatalytic support for methanol oxidation by cyclic voltammetry. The mesoporous carbons loaded with Pt catalysts exhibit two to three times higher mass activity (mA/mg Pt) for methanol oxidation than Vulcan XC 72R carbon loaded with Pt. The enhanced activity is attributed to a better dispersion and utilization of the catalysts, originating from a combination of high surface area and lower percentage of undesirable micropores. Both cyclic voltammetric and chronoamperametric measurements of the Pt-loaded carbon samples indicate that the mesoporous carbon possesses lower hydrophilicity compared to the conventional Vulcan XC 72R carbon. However, the hydrophilicity is found to depend on the aniline/CTABr ratios used during the synthesis of the mesoporous carbon samples.

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