Structural characterization and electrocatalytic properties of Au30Zr70 amorphous alloy obtained by rapid quenching

The present work describes the characteristics of Au₃₀Zr₇₀ amorphous alloy as a precursor of a catalyst for hydrogen evolution both in acid and in basic environments and for oxidation of methanol and formaldehyde in alkaline solutions. Amorphous Au–Zr ribbons were prepared by melt spinning methods and were characterized by X-ray diffraction, optical and scanning electron microscopy. In order to obtain an active electrocatalyst, the surface of the amorphous ribbons was treated by immersion in 1 M HF solution. The results of electrocatalytic tests were compared to those obtained with untreated ribbons and also with electrodes made in polycrystalline pure gold. Moreover, some untreated samples were aged in air for 30 days before the electrochemical measurements, in order to investigate the effect of surface oxidation on the electrochemical behaviour of the alloys. The HF treatment yielded a porous structure rich in nanocrystalline gold particles which had better electrocatalytic activity than untreated ribbons or polycrystalline gold electrodes. Ageing in air produced a duplex phase structure, comprising of ZrO₂ scales and nanocrystalline gold which had also improved electrocatalytic activity.