Premium
Promotion of Hydrogen Desorption from Palladium Surfaces by Fluoropolymer Coating
Author(s) -
Delmelle Renaud,
Ngene Peter,
Dam Bernard,
Bleiner Davide,
Borgschulte Andreas
Publication year - 2016
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201600168
Subject(s) - x ray photoelectron spectroscopy , desorption , hydrogen , permeation , palladium , materials science , fluoropolymer , chemical engineering , membrane , coating , catalysis , chemistry , adsorption , polymer , nanotechnology , organic chemistry , composite material , biochemistry , engineering
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.