Fabrication of H2-permeable palladium membranes based on pencil-coated porous stainless steel substrate

The increasing utilizations of hydrogen energy have greatly promoted the demand on H2-permeable palladium membranes, particularly those supported on porous stainless steel (PSS). A macroporous stainless steel tube was employed as substrate material, and its surface was modified by pencil coating. The palladium membrane was successfully fabricated via electroless plating. Before plating, the Pencil/PSS substrate was simply activated by an immersion in PdCl2−HCl solution, where the PSS and the graphite layer served as anode and cathode, respectively, yielding palladium seeds on the Pencil/PSS surface through galvanic cell reaction. During electroless plating, a peeling of the palladium layer occurred, but this problem can be solved by introduction of a suction treatment, and the resulting Pd/Pencil/PSS membrane was found to be permeable and stable.