An investigation of Pt alloy oxygen reduction catalysts in phosphoric acid doped PBI fuel cells

A study of a phosphoric acid doped polybenzimidazole (PBI) membrane fuel cell using commercial carbon supported, Pt alloy oxygen reduction catalysts is reported. The cathodes were made from PTFE bonded carbon supported Pt alloys without PBI but with phopshoric acid added to the electrode for ionic conductivity. Polarisation data for fuel cells with cathodes made with alloys of Pt with Ni, Co, Ru and Fe are compared with those with Pt alone as cathode at temperatures between 120 and 175 °C. With the same loading of Pt enhancement in cell performance was achieved with all alloys except Pt–Ru, in the low current density activation kinetics region of operation. The extent of enhancement depended upon the operating temperature and also the catalyst loading. In particular a Pt–Co alloy produced performance significantly better than Pt alone, e.g. a peak power, with low pressure air, of 0.25 W cm−2 with 0.2 mg Pt cm−2 of a 20 wt% Pt–Co catalyst.