GLAD Cr Nanorods Coated with SAD Pt Thin Film for Oxygen Reduction Reaction

Vertically aligned chromium nanorod arrays were grown on glassy carbon electrodes by a dc magnetron sputtering glancing angle deposition (GLAD) technique. The Cr nanorods were used as low-cost, high surface area, metallic supports for a conformal Pt thin film, resulting in a potential low-loading electrocatalyst for the oxygen reduction reaction (ORR) in polymer electrolyte membrane (PEM) fuel cells. Conformal coatings of Pt on Cr nanorods were achieved using a dc magnetron sputtering small angle deposition (SAD) technique. The electrocatalytic ORR activity of SAD-Pt/GLAD-Cr electrodes was investigated using cyclic voltammetry and rotating-disk electrode techniques in a 0.1 M HClO4 solution at temperatures ranging from 20 to 60 degrees C, and was compared to those of GLAD Cr nanorods coated with Pt thin film deposited at normal and large angles of incidence. The results show that SAD-Pt/GLAD-Cr nanorods exhibit higher values of electrochemically-active surface area (ECSA), area- and mass-specific activities, and better stability against loss of ECSA during potential cycling in the acidic electrolyte. The improved ORR activity and enhanced catalyst utilization of SAD-Pt/GLAD-Cr electrode might be attributed to a better Pt conformality, especially at the sidewalls of the nanorods, and a preferential exposure of certain crystal facets. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.087206jes] All rights reserved.