Platinum-Coated Nickel Nanowires as Oxygen-Reducing Electrocatalysts

Platinum (Pt)-coated nickel (Ni) nanowires (PtNiNWs) are synthesized by the partial spontaneous galvanic displacement of NiNWs, with a diameter of 150-250 nm and a length of 100-200 mu m. PtNiNWs are electrochemically characterized for oxygen reduction (ORR) in rotating disk electrode half-cells with an acidic electrolyte and compared to carbon-supported Pt (Pt/HSC) and a polycrystalline Pt electrode. Like other extended surface catalysts, the nanowire morphology yields significant gains in ORR specific activity compared to Pt/HSC. Unlike other extended surface approaches, the resultant materials have yielded exceptionally high surface areas, greater than 90 m(2) g(Pt)(-1). These studies have found that reducing the level of Pt displacement increases Pt surface area and ORR mass activity. PtNiNWs produce a peak mass activity of 917 mA mg(Pt)(-1), 3.0 times greater than Pt/HSC and 2.1 times greater than the U.S. Department of Energy target for proton-exchange membrane fuel cell activity.