A grand challenge of vanadium-based H2 permeable membranes is the development of effective, cheap, and stable catalysts to facilitate H2 dissociation and recombination. This work investigates a facile air treatment to form catalytically active vanadium oxide on the surfaces of dense vanadium foils. The treatment consisted of short air exposure followed by H2 reduction at 823 K, which produced a well-faceted and nanocrystalline V2O3 layer on the foil surfaces. The resulting membranes displayed a stable H2 permeability of 2 ± 0.25 × 10–8 mol·m–1·s–1·Pa–0.5, but transient declines in permeation were observed when operated at both elevated and reduced temperatures. DFT calculations revealed that V2O3 (0001) surfaces display barriers and adsorption energies for H2 dissociation/recombination that are comparable to those of known H2 activation catalysts. It was found that H2 dissociation is expected to proceed spontaneously on metal-terminated V2O3, with recombinative-desorption anticipated as the rate limiting step.

Transition metal carbide coated vanadium membranes for hydrogen permeation have the unique ability to operate at both high temperatures and pressures. Titanium carbide deposited by magnetron sputtering produced dense, nanocrystalline films preferentially oriented in the ( 111) plane. When applied on vanadium foils, TiC was a highly active catalytic coating enabling permeation of ultrapure H 2 with fluxes up to 0.71 mol m −2 s −1 at 10 bar and 923 K. The TiC thickness controlled H 2 transport in the composite membranes. Thicker TiC films and low temperature operation yielded n-values >1, which were likely resultant of adsorption effects and surface diffusion through the carbide layer. Competitive adsorption in mixed gas environments inhibited H 2 flux through TiC/V membranes, but addition of thin (50−100 nm) Pd films to the TiC surface instilled chemical resistance and improved permeation at 773 K. Permeation attenuated for membranes with TiC thicknesses <20 nm but 23 nm thick coatings demonstrated stable flux for 30 h.