Hydrogen induced structural modifications in size selected Pd-Carbon core-shell NPs: Effect of carbon shell thickness, size and pressure

摘要

In the present work, the effect of size, pressure and carbon shell thickness on the hydrogen induced structural modifications in Pd-C core-shell nanoparticles (NPs) have been inves-tigated by in-situ X-ray diffraction (XRD) technique. XRD study shows contraction in the lattice with decrease in size of the NPs. Hydrogen pressure dependent alpha-to beta-phase tran-sition is observed on increasing hydrogen pressure (1 x 10(-4 )to 100 mbar). Compared to pure Pd NPs, occurrence of alpha nbsp;? nbsp; nbsp;beta nbsp;phase transition at lower H pressure in Pd-C NPs in-dicates that Pd-H interaction is enhanced by the carbon shell. Further, increasing hydrogen partial pressure is accompanied by an increase in the lattice parameter along with the formation of b-phase. Change in lattice constant (Da) at different rates indicates the relative dominance between adsorption and desorption at different pressures. The merits of Pd-C core shell NPs over bulk analogues make it a promising material for repeated hydrogen cycling applications. (c) nbsp;2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.