Experimental and Numerical Study of Pd/Ta and PdCu/Ta Composites for Thermocatalytic Hydrogen Permeation.

The development of stable and durable hydrogen (H 2 ) separation technology is essential for the effective use of H 2 energy. Thus, the use of H 2 permeable membranes, made of palladium (Pd), has been extensively studied in the literature. However, Pd has considerable constraints in large-scale applications due to disadvantages such as very high cost and H 2 embrittlement. To address these shortcomings, copper (Cu) and Pd were deposited on Ta to fabricate a composite H 2 permeable membrane. To this end, first, Pd was deposited on a tantalum (Ta) support disk, yielding 7.4 × 10 -8 mol H 2 m -1 s -1 Pa -0.5 of permeability. Second, a Cu-Pd alloy on a Ta support was synthesized via stepwise electroless plating and plasma sputtering to improve the durability of the membrane. The use of Cu is cost-effective compared with Pd, and the appropriate composition of the PdCu alloy is advantageous for long-term H 2 permeation. Despite the lower H 2 permeation of the PdCu/Ta membrane (than the Pd/Ta membrane), about two-fold temporal stability is achieved using the PdCu/Ta composite. The degradation process of the Ta support-based H 2 permeable membrane is examined by SEM. Moreover, thermocatalytic H 2 dissociation mechanisms on Pd and PdCu were investigated and are discussed numerically via a density functional theory study.