Surface Modification of Nafion Membrane Electrolyte by the Ion-Beam-Assisted Deposition of Platinum and Rare-Earth Metals.

Layers on the surface of Nafion polymer membrane, which is used as an electrolyte in low-temperature fuel cells, are prepared by the ion-beam-assisted deposition (IBAD) of platinum as the main active metal and one of the rare-earth metals (Gd, Dy, Ho) as an activating additive. Metal deposition and mixing of the deposited layer with the substrate surface by accelerated (U = 5 kV) ions of the same metal are carried out in an experimental setup, respectively, from the neutral fraction of metal vapors and ionized plasma of a pulsed vacuum (p ~ 10^–2 Pa) arc discharge. The composition of the formed layers is studied using scanning electron microscopy, energy-dispersive microanalysis, X-ray fluorescence spectroscopy, and Rutherford backscattering spectrometry. It is found that the resulting layers contained atoms of deposited metals, components of the polymer substrate material, and an oxygen impurity. Their thickness was ~30 nm, the content of each of the deposited metal atoms in the layers was ~n × 10¹⁵ cm^–2. [ABSTRACT FROM AUTHOR]