电沉积镍-储氢合金复合电极的析氢电催化性能

采用电沉积方法制备了镍-稀土储氢合金(Ni—AB5)复合电极，利用稳态极化曲线及电化学交流阻抗技术研究了该电极在28％KOH溶液中的析氢电催化性能，并用扫描电镜观测了电极的表面形貌．结果表明，与电沉积纯Ni电极相比，Ni—AB5复合电极具有较低的析氢过电位和电化学反应阻抗以及较大的交变电流密度和比表面积，在纯Ni及Ni—AB5电极上析氢反应的标准活化自由焓分别为74．2kJ／mol和39．8kJ／mol，即Ni—AB5复合电极表现出较高的析氢电催化活性．复合电极在碱性溶液中的析氢反应符合Volmer—Heyrovsky历程，电化学脱附为反应速度的控制步骤．

Electrocatalysis for Hydrogen Evolution Reaction on Nickel-Hydrogen Storage Alloy Composite Electrodes Prepared by Electrodeposition

Nickel-rare earth hydrogen storage alloy (Ni-AB_5) composite electrodes were prepared by the electrodeposition technique, and their electrocatalytic characteristics for hydrogen evolution reaction (HER) in 28% KOH solution were investigated by steady-state polarization curves and electrochemical impedance spectroscopy (EIS). The morphology of the electrodes was examined by using scanning electron microscopy (SEM). The experimental results show that in comparison with those of the electrodes electrodeposited with pure Ni, the Ni-AB_5 composite electrodes exhibit a lower overpotential and reaction resistance, a higher exchange current density and specific surface area for HER. The standard free activation enthalpy of HER on the pure-Ni and Ni-AB_5 electrodes is 74.2 kJ/mol and 39.8 kJ/mol respectively. Thus the Ni-AB_5 composite electrodes possess a superior electrocatalytic activity for HER as related to the pure-Ni electrodes. The main pathway for HER on the Ni-AB_5 composite electrodes in alkaline solutions is Volmer-Heyrovsky with the electrochemical desorption as the rate-determining step.