Magnetic field-enhanced hydrogen electrocatalysis: Unveiling the role of electrolyte concentration

Abstract

The hydrogen evolution reaction at Ni foam electrodes is enhanced by magnetic fields of up to 12 kOe applied perpendicular to the electric field. While in 1 M KOH, the beneficial change in overpotential at an applied field is on the order of 10 mV, the effect increases drastically when the concentration of OH− is reduced to 0.1 M and 0.01 M, respectively, leading to a change in overpotential of up to 200 mV at the lowest concentration of OH−, making the reaction significantly more energy-efficient. The addition of KCl as a supporting electrolyte effectively suppresses adverse effects originating from the low conductivity of 0.01 M KOH while preserving the advantageous effects of the magnetic field. Finally, the effects are studied in neutral 1 M KCl, likewise leading to an improvement in HER of up to 200 mV in overpotential, and in filtered seawater, where the overpotential improves by 28 mV when applying 12 kOe. The effects of magnetic fields on HER are shown to be reversible, and scale with the magnitude of the field. In addition to chronopotentiometry at −10 mA where magnetic field pulses generate a pulse in the HER overpotential, measurements are complemented by linear sweep voltammetry and electrochemical impedance spectroscopy.