Development of hydrogen-selective TiOxNy-Pd composite membrane materials by atomic layer deposition

Abstract

This work reports on novel hydrogen (H2) selective membrane composed of TiOxNy-Pd nanocomposite thin films prepared by Atomic Layer Deposition (ALD) on asymmetric porous alumina supports. The nanocomposite combines the robustness of a ceramic matrix, selective gas barrier properties of TiOxNy thin layer and specific H2 sorption/affinity of palladium nanoparticles (Pd NPs). Precise control of the thickness and chemical composition of TiOxNy-Pd layer enables to achieve promising H2 selectivities (αH2/N2≈35 and αH2/He≈7) with permeances πH2≈228GPU at 390 °C. At this temperature, TiOxNy crystallites start to form in the initially near-amorphous layer and allow selective transport of H atoms generated during the adsorption-dissociation of H2 on the Pd NPs. This study clearly stresses the effectiveness of ALD in the formation of dense H2-permselective membranes while significantly limiting the production costs by reducing the content of expensive elements, such as Pd. Finally, thanks to the versatility of the ALD technique, the present strategy could be extended to other rational design for applications requiring gas separation or detection.