A new class of materials and new treatment method are proposed to improve the electrocatalytic activity of the AB(2)-type alloys without making use of highly electrocatalytic precious metals such as Pd or Pt. The effects of La on the AB(2) hydriding compounds Zr0.5Ti0.5V0.75Ni1.5 were investigated in terms of alloy microstructure, initial activation, kinetics, hydrogen capacity and F treatment effect. Various analytical techniques such as electron probe micro analysis, electron spectroscopy for chemical analysis, inductively coupled plasma spectroscopy and X-ray diffraction are employed to characterize the alloy structure and surface. It was found that La addition of the Zr-Ti-V-Ni alloys benefit electrode kinetics, and F-treated alloys exhibit easy activation. La is not soluble in the AB(2) phase but rather forms discrete La-rich inhomogeneous sites in the microstructure. These sites remain on the surfaces of crushed powder particles and serve as H-transparent windows through the less transparent AB(2) oxide layer, providing for the fast electrochemical hydrogen reaction. An Ni-rich layer with microcave structure appeared on the F-treated alloy surface and is of benefit to alloy activation. After F treatment the La-Ni phase on the La added alloy surface disproportioned into LaF2 and Ni clusters. The Ni clusters in loose LaF3 layer catalyze the electrochemical reaction and accelerate alloy activation.
