La₂O₃-Modified Nickel-Cobalt Composite Coating as Cathode Materials for Hydrogen Evolution Reaction

Abstract

La 2 O 3 was successfully doped into nickel-cobalt alloy coating on Ti substrate by electrodeposition technology.The surface morphology and microstructure were examined by SEM and XRD, respectively, and the hydrogen evolution property was evaluated by electrochemical techniques, including steady-state polarization, Tafel plot and electrochemical impedance spectroscopy. It was found that the incorporated La 2 O 3 particles resulted in the improvement of roughness and surface area of the composite coating electrode, and hydrogen evolution potential of nickelcobalt-La 2 O 3 composite coating electrode moved positively around 178 mV at 15 mA cm -2 compared with that of nickel-cobalt alloy deposited coating electrode. It was assumed that the enhanced electrocatalytic activity to hydrogen evolution was attributed to the improved surface area and the decreased apparent activation energy, which was verified by hydrogen evolution kinetics parameters calculated from Tafel plots and electrochemical impedance spectroscopy.