Ni-Zr alloys: relationship between surface characteristics and electrocatalytic behavior

A relationship between electrocatalytic activity for the hydrogen evolution reaction and the surface composition of the electrode was established for Ni-Zr crystalline and amorphous alloys by means of secondary ion mass spect rometry (SIMS), Electrocatalytic activity was tested by means of cathodic p olarization in 1 M KOH at 25 degrees C and the resulting exchange current d ensity has been taken as a measure of catalytic efficiency. Surface activat ion treatment involved chemical etching in HP solutions; the consequent mor phological and compositional surface changes were studied by differential s canning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron mi croscopy (SEM), The electrochemical behavior of the pure elements (Ni and Z r) was also considered for comparison. All samples submitted to chemical et ching in HF solutions showed an increase in electrocatalytic activity, part icularly the alloy with the highest Ni content. The beneficial effect of ch emical etching is due to dissolution of the zirconium oxide layer and to th e formation of nanocrystalline Ni on the surfaces. Copyright (C) 2000 John Wiley & Sons, Ltd.