Comparative study of hydrogen evolution behavior of Nickel Cobalt and Nickel Cobalt Magnesium alloy film prepared by pulsed electrodeposition

The hydrogen evolution reaction (HER) for pulsed electrodeposited alloy of nickel cobalt and nickel cobalt magnesium cathode is studied using linear polarization and electrochemical impedance spectroscopy (EIS). EIS is performed at Heyrovsky hydrogen evolution rate determining step. The rate of Hydrogen evolution per unit area is determined. The Field Emission Gun Scanning Electron Microscopy (FEGSEM) shows the roughness of the sample. The X-ray diffraction shows the nickel cobalt deposited in face centered cubic (FCC) structure and nickel cobalt magnesium deposited in mixed phase of NiMg, NiCo, and CoMg. The Equivalent circuit for EIS spectrum is modeled with two CPE (Constant phase element) and Warburg impedance, and fitted using Complex Nonlinear Least Square fitting (Levenberg-Marquardt) method. The Tafel region of hydrogen evolution rate determining step is modeled using Heyrovsky step kinetic equation. The pulsed electrodeposition method of preparing HER cathode improves the structural growth and surface roughness which in turn increases surface hydrogen atom coverage.