Solvothermal synthesis of high hydrogen permeable Pd/Ag alloy particles and their hydrogen transport properties

Abstract

Pd₇₆Ag₂₄ nanoparticles with high purity and a face-centered cubic structure were prepared using a solvothermal method. The lattice parameter of the Pd₇₇Ag₂₃ nanopowders (space group 225Fm3m) was calculated to be a = 3.9382 Å. The primary particle size was calculated to be 7.7 nm from the X-ray line width using the Scherrer formula, and the interplanar distances was estimated to be 2.272 and 2.000 Å based on indexing on the (111) and (200) plane, respectively. These values are slightly larger than those of pure Pd and smaller than Ag in the (111) plane. The linear relationship of the hydrogen permeation flux with the square root of the hydrogen partial pressure gradient across a 0.26-mm-thick Pd/Ag-YSZ cermet membrane confirmed the major hydrogen transport through the Pd/Ag phase of cermet membranes. The Pd/Ag-YSZ cermet membranes showed significantly higher hydrogen permeation flux than the Pd-YSZ cermet membrane, even though the activation energy for the Pd/Ag alloy cermet membranes showed slightly higher values than that of the Pd cermet membranes. The hydrogen–oxygen dual flux through Pd/Ag-YSZ cermet membranes was confirmed by the maximum hydrogen production by combining the ability of hydrogen production from water with the function of hydrogen separation on composite membranes