Pt modified tungsten carbide as anode electrocatalyst for hydrogen oxidation in proton exchange membrane fuel cell: CO tolerance and stability

• CO tolerance of Pt supported on tungsten/carbon (WC/C) composites is investigated.
• The stability of the materials is investigated by an accelerated stress test.
• 20 wt.% W/C-supported Pt shows improved CO tolerance and stability.
• For 20 wt.% W/C-supported Pt, the CO stripping reactions occur at low potentials.
• W/C-supported Pt catalysts present better properties than carbon-supported PtW.

Pt supported on tungsten carbide-impregnated carbon (Pt/WC/C) is evaluated for hydrogen oxidation reaction in hydrogen/oxygen polymer electrolyte fuel cell at two different temperatures (85 and 105 °C), in absence and presence of 100 ppm CO. Carbon supported PtW, prepared by a formic acid reduction method is also evaluated for comparison. At 85 °C, the initial hydrogen oxidation activity in the presence of 100 ppm CO is higher for Pt/WC/C, showing a CO induced overpotential of 364 mV for 1 A cm−2 of current density as compared to an overpotential of 398 mV for PtW/C. As expected, an increase in CO tolerance is observed with the increase in cell temperature for both the catalysts. The increased CO tolerance of Pt/WC/C catalyst is in agreement with CO stripping experiments, for which the CO oxidation potentials occurred at lower potentials at three different temperatures (25, 85 and 105 °C) in comparison to PtW/C. The stability of both electrocatalysts is evaluated by an accelerated stress test and the results show a better stability for Pt/WC/C catalyst. On the basis of cyclic voltammograms and polarization curves, it is concluded that Pt/WC/C is more stable than PtW/C and can be used as alternative anode catalyst in PEMFC, especially at high temperatures.

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