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.