Nanocrystalline vanadium carbides as highly active catalysts on vanadium foils for high temperature hydrogen separation

Abstract

Vanadium carbide (VC) was demonstrated as an effective H2 dissociation/desorption catalyst for membrane applications in high temperature hydrogen separation. Nanocrystalline VC films with rich carbon vacancies were prepared on both sides of vanadium (V) using radio frequency magnetron sputtering. Combined structural, catalytic and density functional theory (DFT) analysis suggest that carbon vacancies significantly increase the electron density around the Fermi level of VC crystals and lower the energy barrier for hydrogen catalytic reactions. Such thin VC films are highly active to H2 dissociation/desorption at high temperatures. Hence, the prepared VC/V composite membranes exhibit much higher hydrogen permeability than commercially used Pd at evaluated temperatures, particularly 8.2 × 10-8 mol H2 m−1 s−1 Pa−0.5 at 700 °C (2.5 times that of Pd). These findings open a new way towards the development of non-Pd hydrogen separation membranes for sustainable hydrogen technology.