镍锡析氢活性阴极的电化学制备及其在碱性溶液中的电催化机理

采用恒电流电沉积法在铜箔基底上获得镍锡合金镀层电极. 电子能谱(EDS)、X射线衍射(XRD)以及高分辨透射电镜(HRTEM)分析表明, 随着锡含量的增加, 镀层由镍晶胚与非晶镍锡构成的非晶态结构转变为Ni₃Sn₄与Ni₃Sn₂的混晶结构. 扫描电镜(SEM)分析发现, 非晶结构镍锡合金电极表面粒子分布均匀且粒径细小, Ni₃Sn₄与Ni₃Sn₂混晶结构的镍锡合金电极表面粗糙且断面呈分层自组装结构. 在25℃, 1 mol·L^-1 NaOH溶液中的稳态极化曲线表明非晶结构的镍锡合金电极具有良好的催化活性, 其析氢过电位仅为85 mV. 交流阻抗测试表明, 非晶以及混晶结构的镍锡合金在析氢电催化反应过程中由电化学吸附(Volmer)以及电化学脱附(Heyrovsky) 两个电荷转移过程控制, 且非晶结构电极相比于Ni₃Sn₄与Ni₃Sn₂混晶结构电极的高活性源于其活性氢具有更快的电化学吸附以及脱附速度.

Electrochemical Preparation of Ni-Sn Active Cathode and Its Electrocatalytic Hydrogen Evolution Reaction Mechanisms in Alkaline Solution

A simple galvanostatic electrodeposition method was used to synthesize an active Ni-Sn electrode on a Cu foil substrate. Characterization by high-resolution transmission electron microscopy (HRTEM), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD) revealed that the crystal structures of the deposited films transformed from amorphous structures composed of Ni crystal embryos and amorphous Ni-Sn to Ni₃Sn₄/ Ni₃Sn₂ mixed crystals with increasing Sn content. Scanning electron microscope (SEM) images indicated that the amorphous Ni-Sn electrode possessed a smooth surface with uniform distribution of small particles, whereas the Ni₃Sn₄/Ni₃Sn₂ mixed crystalline electrode exhibited a rough surface composed of lamellar structures. The polarization curves measured in 1 mol·L^-1 NaOH solution at 25℃ indicated that the amorphous Ni-Sn electrode showed a smaller overpotential (85 mV) and better electrocatalytic performance for hydrogen evolution than the mixed crystalline electrode. Electrochemical impedance spectroscopy (EIS) results showed that the hydrogen evolution reaction occurs on the Ni-Sn alloy electrode under a mixture of Volmer and Heyrovsky control. The higher activity of the amorphous Ni-Sn electrode was attributed to the faster charge transfer and electrochemical adsorption and desorption rates of hydrogen atoms compared with those on the mixed crystalline electrode.