Preparation and characterization of Pd and Pd-Ni alloy membranes on porous substrates by MOCVD with mixed metal β-diketone precursors

A novel metal-organic chemical vapor deposition(MOCVD) process with a mixed metal β-diketone precursor to successfully prepare Pd and Pd-Ni alloy composite membranes is described. A palladium phase deposit consisting of agglomerates of tiny crystallites with a dimension of around 30 × 10 nm was formed on porous A12O3 substrates, when using a single Pd(AcAc)2 precursor. With a mixed precursor of Pd(AcAc)2 + Ni(AcAc)2, uniform and dense Pd-Ni alloy membranes (consisting of primary crystallites with a dimension of 40 × 15 nm) were reproducibly obtained on porous alumina supports. N2 permeation tests indicated that the Pd-Ni alloy layer was gaslight and crack-free. XPS studies revealed that no oxygen nor carbon impurities were incorporated into the bulk membranes. The PdNi ratio on the surface of Pd-Ni alloy layer was very close to that of the mixed precursor, but much less Ni content (<1150) was detected in the deposit body.