GLAD Pt-Ni Alloy Nanorods for Oxygen Reduction Reaction

Vertically aligned platinum nickel (Pt-Ni) alloy nanorod arrays were grown on glassy carbon electrodes using a magnetron sputtering glancing angle deposition (GLAD) technique. X-ray diffraction and electron microscopy results show that the as-deposited nanorods are alloys and that the alloy composition and geometric properties of Pt-Ni nanorods can be changed by controlling the GLAD deposition parameters. The GLAD Pt-Ni nanorod electrodes were investigated as potential electrocatalysts for the oxygen reduction reaction (ORR) in polymer electrolyte fuel cells (PEFCs) using cyclic voltammetry (CV) and rotating-disk electrode (RDE) techniques in aqueous perchloric acid electrolyte. The electrochemically active surface area (ECA), determined from the charge for hydrogen adsorption and desorption in the CVs, was estimated to be a factor of 3 or more larger than the geometric surface area of the nanorods. The ORR mass-specific activity of the Pt-Ni nanorods was found to be a factor of 2.3-3.5 higher than that of pure Pt nanorods of the same dimensions and increase with increasing Ni content, whereas ORR area-specific activity enhancement was only observed for the nanorods with the highest Pt content. In addition, the Pt-Ni nanorods were found to have higher stability against loss of ECA during potential cycling than Pt nanorods and conventional high-surface-area-carbon-supported Pt nanoparticles.