Electrocatalytic activity and electrochemical hydrogen storage of Ni-La alloy prepared by electrodeposition from aqueous electrolyte

Ni睱a alloy coating was prepared by electrodeposition. The effect of cathodic current density on the La content of the alloy coatings was discussed. It is found that the content of La in the alloy increases with increasing the cathodic current density. The microstructures and codeposition mechanism of Ni La alloy coatings were investigated by means of X ray diffraction (XRD) and cyclic voltammetry (CV). The results demonstrate that the Ni La alloy is FCC and codeposited by the induced mechanism. The hydrogen evolution reaction (HER) on the electrodeposited Ni La alloy electrodes in alkaline solution was evaluated by Tafel polarization curves. It is found that La Ni alloy coating exhibites much higher exchange current density for HER than pure Ni electrode, and that the exchange current density increases with increasing the La content of alloys. The good electrocatalytic activity for HER of this Ni La alloy is attributed to the synergism of the electronic structure of La and Ni. The electrodeposited La Ni alloys have a certain electrochemical hydrogen storage capacity of 34 ～ 143?mAh/g, which increases with increasing the La content of alloys.