Promotion of Hydrogen Desorption from Palladium Surfaces by Fluoropolymer Coating

Journal article (2016)

Authors

Renaud Delmelle Swiss Federal Laboratories for Materials Science and Technology (Empa)

P. Ngene ChemE/Materials for Energy Conversion and Storage -

B. Dam ChemE/Materials for Energy Conversion and Storage -

Davide Bleiner Swiss Federal Laboratories for Materials Science and Technology (Empa)

Andreas Borgschulte Swiss Federal Laboratories for Materials Science and Technology (Empa)

Research Group

ChemE/Materials for Energy Conversion and Storage () (TU Delft)

Polymer coatings Membranes Palladium Electrostatic interactions Hydrogen desorption

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Published Date

09-05-2016

Language

English

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Faculty

Applied Sciences

Department

ChemE/Chemical Engineering

Research Group

ChemE/Materials for Energy Conversion and Storage

Abstract

The catalytic activity of Pd surfaces towards hydrogen desorption was significantly improved by a nanometer-thin polytetrafluoroethylene (PTFE) layer, as shown by an enhancement in the permeability of a Pd membrane coated on the permeate side. The origin of this effect was found to be due to a lowering of the barrier for hydrogen desorption, as evidenced by a change in the rate-limiting mechanism of hydrogen permeation through the membrane from desorption (un-coated) to diffusion controlled. In situ X-ray photoelectron spectroscopy (XPS) revealed the electronic structure of the sputtered PTFE. Apart from C-F_n subunits (n=1, 2, 3), we found that nonsaturated carbon atoms became hydrogenated during hydrogen permeation, which was indicative of an interaction between Pd and PTFE. This interaction was weak; no Pd-F bonds were formed. We thus attributed the effect to an increase in the hydrophobicity of the surface by the porous PTFE layer and to a promoter effect of hydrogen desorption as a result of electrostatic interactions between chemisorbed hydrogen and physisorbed PTFE.