Direct ammonia fuel cell performance using PtIr/C as anode electrocatalysts

Direct ammonia fuel cell (DAFC) performance was investigated using as anode PtIr/C electrocatalysts (Pt:Ir atomic ratios of 50:50, 70:30, 80:20 and 90:10) prepared by the borohydride reduction process and NH sub(4)OH 1.0, 3.0 and 5.0 mol L super(-1) in KOH 1.0 mol L super(-1) as fuel. X-ray analyses of PtIr/C electrocatalysts suggested the formation of PtIr alloy and the transmission electron micrographs showed the average particle diameters between 4.5 and 6.0 nm. Using PtIr/C 50:50 electrocatalyst and NH sub(4)OH 5.0 mol L super(-1) in KOH 1.0 mol L super(-1) at 40 degree C a maximum power density was 48% and 70% higher than that obtained using Pt/C and Ir/C electrocatalysts, respectively. The increase of electroactivity using PtIr/C electrocatalysts might be related to a decrease of poisoning on catalyst surface by N sub(ads) species and to an improved kinetic for ammonia oxidation reaction.