Hydrogen adsorbed on nickel, palladium and platinum powders

Abstract

In a recent paper Braid et al. have suggested that their inelastic neutron-scattering data for hydrogen adsorbed by palladium black indicates that hydrogen occupies one- and two-coordinated sites at the surface. It is shown that these assignments imply an unrealistically small palladium–hydrogen bond length, R_HPd= 1.52 Å. Analysis of the vibrational spectra of hydrogen no nickel, palladium and platinum powders presented here suggests three-coordinated adsorption on all three metals, with bond lengths R_HNi= 1.84 Å, R_HPd= 1.88 Å and R_HPt= 1.90 Å.