Parameter physics on hydrogen storage by classical molecular dynamics method

Hydrogen storage in a model b.c.c. metallic nanopartide was simulated by molecular dynamics method by changing length and energy parameters of metal-H bonds. A global image of hydrogen storage from the gas phase into the metallic nanoparticle was successfully reproduced by a single simulation. In case of weak metal-H bonds, hydrogen atoms rapidly diffuse into the particle and distribute homogeneously. The amount of absorbed hydrogen is maximized at optimized bond length, and decreases for both longer and shorter bonds. In case of strong metal-H bonds, hydrogen atoms localize in a shell-like layer near the particle surface and their inward diffusive motions are suppressed. Such a trapping phenomenon of hydrogen atoms near the surface is caused by low hydrogen diffusivity and lattice deformation due to the hydrogen absorption.