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

Abstract

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 HClO 4 solution at temperatures ranging from 20 to 60 • 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 SADPt/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.

SAD-GLAD core-shell nanorod arrays for fuel cell, photodetector, and solar cell electrode applications

“…Table I summarizes the electrochemical characterization results obtained from CV and RDE tests. [15] The results show that SAD-Pt/GLAD-Cr nanorods exhibit higher values of electrochemically-active surface area (ECSA), area-specific activity (SA), and mass-specific activity (MA), 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 has been attributed to a better Pt conformality, especially at the sidewalls of the nanorods, and a preferential exposure of certain crystal facets.…”

“…For this purpose, we recently demonstrated the feasibility of fabricating catalyst-shell/metal-core nanorod arrays using the SAD-GLAD approach. [15] We coated chromium GLAD nanorod arrays, which served as the low-cost, high-surface-area, electronically-conductive support, with a thin SAD Pt catalyst layer. The conformality and electrochemical performance of the SAD Pt films have also been compared to conventional Pt films deposited at normal incidence.…”

“…More details on the fabrication process can be found in Ref. [15]. Briefly, vertically-aligned chromium nanorod arrays were grown on glassy carbon electrodes by a dc magnetron sputtering GLAD technique (Fig.…”

“…In fact, due to the small substrate tilt angles used, SAD coatings can be more easily scaled up for high volume fabrication in industrial deposition systems. [13] Recently, we demonstrated the fabrication of core-shell nanorod arrays using SAD and GLAD methods [15] , which provides a simple method of producing compound nanostructured coatings. Core-shell nanostructures have received the attention of many researchers due to their attractive properties such as high surface area, shorter pathways between the core and shell materials, and surface passivation of the base core nanostructure.…”

“…Core-shell nanostructures have received the attention of many researchers due to their attractive properties such as high surface area, shorter pathways between the core and shell materials, and surface passivation of the base core nanostructure. [15] These properties can offer enhancement in several physical, chemical, and electrical properties. Here, we summarize some of the important findings from our recent results on the fabrication and growth modelling of SAD-GLAD core-shell nanorod arrays, and their applications in fuel cell and photodetector electrodes.…”