Near-Edge X-ray Absorption Fine Structure Analysis of Magnesium-Palladium Nanoparticles Fabricated by Gas Evaporation Method

Abstract

The change of the chemical state of the Mg-Pd nanoparticles during hydro-/dehydrogenation has been investigated by the near edge x-ray absorption fine structure (NEXAFS) measurements under the in-situ condition. The Mg-Pd nanoparticles have been fabricated by the gas evaporation method using He gas and embedded in the fluorine resin in order to protect the Mg-Pd nanoparticles from the oxidation of the Mg-Pd nanoparticles. The Pd L3-edge NEXAFS measurements have been carried out under the flowing the diluted hydrogen gas (4 wt% H2) and pure He gas for the hydrogenation and dehydrogenation of the Mg-Pd nanoparticles, respectively. The in-situ Pd L3-edge NEXAFS analyses have revealed that the Pd phases in the Mg-Pd nanoparticles are hydrogenated under the diluted hydrogen gas atmosphere. The subsequent dehydrogenation of the Pd phases has not been observed under the He gas. This result indicates that the dehydrogenation reaction of the Pd has been inhibited by the irreversible migration of the Mg toward the surface of the Mg-Pd nanoparticles.