电沉积Ni-S／LaNi5多孔复合电极的电催化析氢性能

Electrocatalytic hydrogen evolution characters of electrodeposited Ni-S/LaNi_5 porous composite electrode

采用复合电沉积结合碱溶制备Ni-S/LaNi5多孔复合电极,并采用SEM、EDS和XRD等技术表征电极的表面形貌、元素组成和镀层的晶形结构。运用阴极极化曲线研究该电极在20%(质量分数)NaOH溶液中的析氢电催化性能,通过间断恒电位电解、长时间恒电位电解研究电极的稳定性,用长时间电解后开路电位和阳极极化探讨电极稳定性的原因。结果表明:与电沉积Ni-S多孔电极相比,Ni-S/LaNi5多孔复合电极具有较低的析氢过电位和电化学反应阻抗及较大的交换电流密度和比表面积。在Ni-S多孔及Ni-S/LaNi5多孔复合电极上,析氢反应的表观活化自由能分别为78.08和49.41 kJ/mol,Ni-S/LaNi5多孔复合电极表现出较高的析氢电催化活性和稳定性。

The Ni-S/LaNi 5 porous composite electrodes were prepared by composite electrochemical deposition technique in combination with alkaline dissolving. The corresponding micrographs, element component and structures of the Ni-S/LaNi 5 porous composite electrode were characterized by scanning electron microscopy （SEM）, energy dispersive X-ray （EDS） and X-ray diffractometry （XRD）. Their electrocatalytic characteristics for hydrogen evolution reaction （HER） in 20% （mass fraction） NaOH solution were investigated by cathodic polarization curves （CPC）. Their stabilization was studied by constant potential with discontinuity electrolysis and constant potential electrolysis. The reason of the electrode stabilization was discussed by open-circuit potential （OCP） after constant potential electrolysis and anodic polarization curves. The results show that the Ni-S/LaNi 5 porous composite electrode for HER exhibits a lower overpotential and a higher exchange current density than the Ni-S porous electrode. The apparent activation energies of HER on the Ni-S porous and Ni-S/LaNi5 porous composite electrode are 78.08 and 49.41 kJ/mol, respectively. Thus, the Ni-S/LaNi 5 porous composite electrode possesses a superior electrocatalytic activity and stability for HER corresponding to the Ni-S porous electrode.