Effect of annealing process on the hydrogen permeation through Pd–Ru membrane

In this paper, we report the effect of the annealing process on the hydrogen permeation in/through Pd–Ru membranes. Pd–Ru membranes were deposited via sequential electroless plating method and annealed at different atmospheres and temperatures. The membranes were characterized by XRD, AES, SEM and hydrogen permeation test. The result shows that Ru is amorphous for the as-deposited Pd–Ru membrane. After annealing in H2, N2 atmospheres and vacuum at temperatures higher than 923 K, amorphous Ru transformed into crystalline Ru, and bubble-like cavities appear. The membrane annealed in H2 has larger and more bubble-like cavities compared with those annealed in N2 and vacuum. And the hydrogen permeabilities of Pd–Ru membranes annealed in H2, N2 atmospheres and vacuum decrease by 45–67% compared with that of the original as-deposited one. Furthermore, after annealed in hydrogen permeation process, the Pd–Ru membrane keeps compact and defect-free, and the Ru membrane remains in amorphous state. The hydrogen permeability of such Pd–Ru membrane is 1.2–1.3 times higher than that of the as-deposited one, which is mainly attributed to the dense structure and amorphous Ru in the membrane. [Display omitted] •Cavities appear in membrane after annealing in H2, N2 and vacuum higher than 923 K.•Amorphous Ru transforms into crystalline Ru after annealing in H2, N2 and vacuum.•Ru in Pd–Ru membrane remains amorphous after permeation annealing.•Amorphous Ru after annealing attributes for increase of hydrogen permeability.