Electrochemical hydrogen storage behavior of Hg-Fe-Ni on graphite in alkaline media

The electrochemical properties of hydrogen evolution reaction and hydrogen storage behavior of Hg-Fe-Ni on graphite (C/Hg-Fe-Ni) were examined in 0.1M NaOH using Cyclic voltemetry(CV), chronopotentiometery(CP), Tafel polarization and electrochemical impedance spectroscopy(EIS). The examination of the physical features and chemical composition of the alloy was conducted using a field emission scanning electron microscope and Energy-dispersive X-ray spectroscopy. The electrochemical discharge capacity of C/Hg-Fe-Ni, was obtained 20302 mAh/g, which was about 6 times higher than the capacity of C/Hg-Ni (3577 mAh/g). Discharge capacity of C/Hg-Ni-Fe in repeated cycles was studied, the electrode's performance peaks at the 13th cycle, reaching a value of 1(100% yield), indicating the excellent performance of this electrode. After 140 cycles, the hydrogen evolution reaction activity has negligible change. In the following, the impact of applied current, the charging duration and the time lag between charging and discharging on the discharge capacity of the electrode were examined. The C/Hg-Fe-Ni also exhibits significantly superior catalytic efficacy for hydrogen evolution reaction evidenced by the obtained Tafel slope value, the exchange current density, and over potential that was found -5.7 mVdec ⁻¹ , 1.45 mAcm ⁻² and 140 mV (vs. RHE), respectively. The diffusion coefficient of hydrogen into the ternary C/Hg-Fe-Ni was also obtained 1.7×10 ⁻¹⁴ cm ² s ⁻¹ . The C/Hg-Fe-Ni electrode can be recognized as an efficient easy prepared electrode for both electrochemically hydrogen storage and hydrogen evolution reaction.