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 CH4 as the carbon source to form the NbC/V composite membranes for hydrogen separation and purification. The effects of CH4 gas flow ratio (F-CH4 = CH4/(CH4+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 Nb2C to the single-phase of cubic NbC after the addition of CH4 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 x 10(-8) mol H-2 m(-1) s(-1) Pa-0.5 at 650 degrees C, which is 2.4 times that of pure Pd.

Automated summary

Niobium carbide (NbC) catalytic films were deposited on the surface of vanadium (V) substrates for hydrogen separation and purification. The addition of CH4 gas changed the structure of NbC film and increased the carbon content but decreased the crystallinity. The NbC/V composite membrane showed the highest hydrogen permeation performance at an F-CH4 of 5%.