Synthesis and electrocatalytic oxygen reduction properties of truncated octahedral Pt₃Ni nanoparticles

Pt₃Ni nanoparticles have been obtained by shape-controlled synthesis and employed as oxygen reduction electrocatalysts for proton exchange membrane fuel cells (PEMFC). The effects of varying the synthesis parameters such as the types of the capping agent and the reducing agent, and the reaction time have been systematically studied. The as-prepared Pt₃Ni nanoparticles were subjected to a butylamine-based surface treatment in order to prepare carbon-supported electrocatalysts. The Pt₃Ni electrocatalysts show an areaspecific activity of 0.76 mA/cm²(Pt) at 0.9 V in an alkaline electrolyte, which is 4.5 times that of a commercial Pt/C catalyst (0.17 mA/cm² (Pt)). The mass activity reached 0.30 A/mg(Pt) at 0.9 V, which is about twice that of the commercial Pt/C catalyst. Our results also show that the area-specific activities of these carbon-supported Pt₃Ni electrocatalysts depend strongly on the (111) surface fraction, which is consistent with the results of a study based on Pt₃Ni extended single-crystal surfaces.