The hydrogen absorption energy and the density of states (DOS) are calculated based on the density functional theory to study the effect of alloying elements on the properties of Pd-M solid solution alloys (M = Rh, Pd, Ag, Ir, Pt, Au). The calculated H absorption energy shows a dependence on the identity of the alloying elements and the trend indicates a correlation with experimental result. The calculation results suggest that the local environment surrounding the H atoms strongly affects the H absorption energy. That is, the first nearest-neighbors of the H atom determine the stability of the system and this implies that H absorption capacity of the entire alloys attributes to the atomic-scale configurations. The DOS provides a good explanation of these observations. Hybridization between the nearest-neighbor metals and H shows evidence of the contribution of the local environment. Furthermore, the elemental dependence of the H absorption energy for each alloy is explained by the DOS near the Fermi energy, which is found to influence the stability of H absorption.
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