Nanoscale Thin Films of Niobium Oxide on Platinum Surfaces: Creating a Platform for Optimizing Material Composition and Electrochemical Stability

A nanoscale thin film of niobium oxide on a platinum substrate was evaluated for its influence on the electronic and chemical properties of the underlying platinum towards the oxygen reduction reaction with applications to proton exchange membrane fuel cells. The nanoscale thin film of niobium oxide was deposited using atomic layer deposition onto the platinum substrate. A film of niobium oxide is a chemically stable and electronically insulating material that can be used to prevent corrosion and electrochemical degradation when layers are several nanometers thick. These layers can be insulating if sufficiently thick and may not be sufficient to protect the platinum from corrosion if too thin. An ∼3 nm thin film of niobium oxide was fabricated on the platinum surface to determine its influence on the electronic and chemical properties at the interface of these materials. The atomic layer deposition process enabled a precise control over the material composition, structure, and layer thickness. The niobium oxide film was evaluated using cyclic voltammetry and electrochemical impedance spectroscopy to evaluate whether a balance could be found between the inhibition of platinum degradation and electronic insulation of the platinum for use in proton exchange membrane fuel cells. The 3 nm thin niobium oxide film was found to be sufficiently thin to permit electronic conductivity while reducing the incidence of platinum dissolution.