Metallic glasses as novel catalysts

Abstract

Metallic glasses are nonequilibrium amorphous metal alloys which combine the metallic electronic structure with a disorered atomic structure usually reserved for ceramic and polymeric materials. Amorphous silicon-based structures have already been shown to be effective in semiconductor^1,2 and photovoltaic applications³, where single crystal structures were previously thought to be required. The properties of metallic glasses have been reviewed recently by Gilman⁴ and Turnbull⁵. Recent reports demonstrate that metallic glasses are indeed both catalytically active⁶ and uniquely selective⁷. Here we disclose the nature of this unique selectivity. We report observations of glassy Pd–Si and Pd–Ge alloys which exhibit different selectivity in catalysis of hydrogen reactions than their crystalline Pd systems. We also observe an increase in the activity of these amorphous catalysts when partial crystallization occurs.