Understanding the surface state and proton adsorption phenomena on ni-based alloys at the hydrogen evolution zone in alkaline medium by EIS-XPS

In this work, well-defined Ni-based alloys, labeled M1 (Ni _0.8CoO_0.1Zn_0.05MnO_0.02Ti _0.01Y_0.01Al_0.01) and M2 (NiO _0.8CoO_0.1Zn_0.05MnO_0.02Ti _0.01Y_0.01Al_0.01), were prepared by ball-milling technique and used as electrodes for the generation of hydrogen. Electrochemical Impedance Spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) were employed in order to understand the surface state and proton adsorption phenomena during cathodic polarization. It was found that high concentration species such as NiO and/or Ni(OH)₂ induces passivation effect, suppressing the HER by increasing the electrode resistance. The charge transfer, double layer capacitance and adsorption of protons toward the electrode interface ware found to be highly controlled by the intrinsic nature of the alloy in turn.