电沉积方法制备镍硫析氢电极及其电化学性能

采用恒电流电沉积方法制备Ni-S电极,通过极化曲线研究了硫脲质量浓度、电流密度、镀液温度、电沉积时间等对Ni-S电极析氢性能的影响,获得了较佳的制备工艺:NiSO4·6H2O187.2g/L,硫脲100g/L,H3BO340g/L,NaCl 20g/L,pH=4,电流密度30 mA/cm2,镀液温度55℃和电沉积时间1...

Preparation of nickel-sulfur electrode by electrodeposition and its electrochemical performance

Ni–S electrodes were prepared by constant current electrodeposition. The influence of the mass concentration of thiourea,current density,temperature of electroplating bath and electrodeposition time on the hydrogen evolution performance of Ni–S electrode was studied with polarization curves. A good preparation process was obtained as follows:NiSO4·6H2O 187.2 g/L,thiourea 100 g/L,H3BO3 40 g/L,NaCl 20 g/L,pH 4,current density 30 mA/cm2,bath temperature 55 °C and electrodeposition time 120 min. The Ni–S deposit was characterized by scanning electron microscopy,energy-dispersive spectroscopy and X-ray diffraction. The electrochemical performance of Ni–S electrode was studied,and the hydrogen evolution overpotentials on Ni–S electrode,pure Ni electrode and mildsteel electrode were compared at different current densities in 6 mol/L NaOH solution at 25 °C. The results indicated that the microstructure of Ni–S deposit is compact and amorphous,which consists mainly of Ni and S elements,and contains 13.61% S. The hydrogen evolution overpotential on Ni–S electrode is lower than that on the pure Ni electrode by 309 mV and the mild steel electrode by 354 mV at a current density of 100 mA/cm2. The hydrogen evolution overpotential on Ni–S electrode is decreased with increasing electrolyte temperature in range of 60-90 °C. For example,the overpotential is 63 mV at 90 °C. The electrode reactions at different current densities follow different reaction mechanisms. The apparent activation energy is 19.57 kJ/mol when the current densities is in range of 0.1-1.0 A/cm2. The electrochemical impedance spectrum of the electrode consists of two capacitive arcs containing Hads pseudocapacitance at overpotential of 150 mV.