Preparation and characterization of Pd–Cu/V–15Ni composite membrane for hydrogen permeation

Pd100−xCux/V–15Ni composite membranes (x = 0, 20, 30, 40, 50, 60 wt.%) were deposited for the first time by co-sputtering in this paper. XRD, SEM and AES were performed to characterize the composite membrane, and its deposition conditions were studied and optimized. Cu concentration of the Pd–Cu overlayer shows a linear dependence on the Cu target sputtering voltage, and it can be expressed as: xCu (wt.%) = 0.45VCu − 138 (where VPd = 340 V, and VCu > 300 V). SEM observation shows that the overlayer films have very dense and fine microstructure; the depositing rate is about 3.5 nm/s when the Pd and Cu target voltages are set as 340 and 395 V, respectively. The Pd100−xCux (x = 0–60 wt.%) nano-overlayer presents a continuous fcc solid solution structure at room temperature, and the variation of its lattice spacing with Cu content agrees well with the Vegard's law. The obtained Pd60Cu40/V–15Ni composite membrane shows higher hydrogen permeability than that of Pd60Cu40 alloy membrane and presents good feasibility to replace the Pd60Cu40 alloy membrane for hydrogen purification in the temperature range of 423–673 K.