A new approach to prepare highly loaded palladium

In this work, a simple procedure to prepare black-Pd films with a high H/Pd loading ratio is reported. The proposed methodology relies on a nonconventional H-source, the hypophosphite ion. Anomalous high loading ratios, H/Pd > 1, were found, however, it was concluded that the hyperstoichiometric hydrogen was independent of the H-source but was intrinsic to the surface properties of the prepared Pd-black film. Hydrogen loading was also determined from GIXRD analysis and a PdH0.79 stoichiometry was found. The atypical H/Pd loading ratio was attributed to H2 trapping by surface voids. The Pd-black film, prepared by a spontaneous deposition process, was characterized by cyclic voltammetry and AFM.