Reactive magnetron sputtering to enhance the hydrogen permeation performance of NbC/V composite membranes.

Niobium carbide (NbC) catalytic films were deposited on the surface of vanadium (V) substrates by reactive magnetron sputtering (RMS) using CH 4 as the carbon source to form the NbC/V composite membranes for hydrogen separation and purification. The effects of CH 4 gas flow ratio (F CH4 = CH 4 /(CH 4 +Ar)) on the phase structure, surface microstructure and catalytic properties of NbC films and the hydrogen permeation performance of the NbC/V composite membranes were investigated. The results showed that the structure of the NbC catalytic film changed from the dual-phase of NbC and Nb 2 C to the single-phase of cubic NbC after the addition of CH 4 gas. Furthermore, with the increase of F CH4 , the carbon content in the NbC catalytic films increases, but the crystallinity decreases. When F CH4 is 5%, the hydrogen permeation performance of the NbC/V composite membrane is the highest, which is attributed to the appropriate carbon content and crystallinity of the NbC phase. Typically, the hydrogen permeability is 7.0 × 10−8 mol H 2 m−1 s−1 Pa−0.5 at 650 °C, which is 2.4 times that of pure Pd. • After the addition of CH 4 gas, the structure of NbC film is the single NbC phase. • The CH 4 gas flow ratio significantly affects the performance of NbC/V membranes. • The highest H 2 permeability of NbC/V membranes is 2.4 times that of pure Pd. • NbC/V membranes exhibit high hydrogen permeation stability at high temperatures. [ABSTRACT FROM AUTHOR]