Study of synergistic effects and compositional dependence of hydrogen evolution reaction on MoxNiy alloy thin films in alkaline media

Abstract

In this paper hydrogen evolution reaction (HER) on the molybdenum-nickel thin films has been studied. The MoxNiy thin films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). A change in the crystal structure of the samples prepared at different temperatures was observed. The structure of the samples prepared at 25 °C are bcc or amorphous. The structure of alloys sputtered at 800 °C changed to fcc. Tafel plots were constructed for each MoxNiy alloy sample. The mechanism of HER was determined from Tafel slope analysis. Values of charge transfer resistance were also determined by impedance spectroscopy. The compositional dependence of activity and the stability of MoxNiy thin films in 1 M NaOH were determined by cycling and chronoamperometry. Our results demonstrate that MoxNiy thin films prepared at 800 °C show significantly improved activity compared to pure Mo and Ni metals. On the other hand, MoxNiy thin films sputtered at 25 °C do not show increased activity in comparison to pure Ni metal. This points to a synergistic effect between fcc Mo and fcc Ni in thin films sputtered at elevated temperatures. Mo63Ni67 thin films alloy prepared at 800 °C shows the best values of catalytic activity for HER from all investigated compositions.