Electrochemical Properties of Pt Coatings on Ni Prepared by Atomic Layer Deposition

Abstract

Presented herein is an approach to fabrication of Pt coatings on non-noble metals with (sub)monolayer thickness. The Pt coatings were prepared using atomic layer deposition (ALD) in which Ni-disk substrate is exposed to and in alternating cycles. The structure and electrocatalytic activity of the coatings were characterized using elemental analysis and various electrochemical techniques. We found that the ALD results in micrometer-size Pt islands up to ca 3.7 monolayers of Pt loading and continues more uniformly at higher loadings. The islandlike growth at low Pt loadings is attributed to the presence of adsorbed O on atomically rough facets of polycrystalline Ni substrate. The thin films of Pt on Ni show enhancement factors in the oxygen reduction reaction similar to what has been reported for PtNi alloys. Potential applications of the methodology demonstrated in this work for the development of the third-generation polymer electrolyte fuel cell catalytic layers with ultralow Pt loading are briefly discussed.