Synergistic modulation of active sites in multi-dopant AxNi1-xFe2O4 nanocatalysts for high-efficiency electrochemical water splitting

Abstract

The genesis of high-efficiency, persisting, and sustainable electrocatalysts that can power both the Hydrogen Evolution Reaction (HER) and the Oxygen Evolution Reaction (OER) is one of the key barriers in advancing the production of hydrogen, a feasible substitute for fossil fuels. In the present investigation, solution combustion was the procedure employed to synthesize Copper, Chromium and Zinc-doped Nickel Ferric Oxide A_xNi_1-xFe₂O₄ where (A = Cu, Cr, and Zn) (X = 0.01, 0.02, 0.03 %) nanoparticles, which were then investigated as Transition Metal Oxides-based electrocatalysts for overall water splitting. The developed Zn_0.02Ni_0.98Fe₂O₄ electrocatalyst demonstrated outstanding OER performance at 1.67 V ($\eta$ = 442 mV) vs. RHE in 1 M KOH electrolyte and extraordinary HER activity was displayed by Cu_0.03Ni_0.97Fe₂O₄ electrocatalyst which exhibited a current density of 10 mA cm⁻² at a potential of −0.160 V ($\eta$ = 160 mV) vs. RHE. Overall water splitting was achieved with the best-performing electrodes (Zn_0.02Ni_0.98Fe₂O₄ || Cu _0.03Ni _0.97Fe₂O₄) at a constant current density of 50 mA cm⁻² in a 24 h stability test. The electrodes achieved a cell voltage of about 2.2 V. During this time, there was very little degradation evident—just a slight increase of 30 mV from the initial voltage. These results highlight the possibility of doping NiFe₂O₄ nanoparticles with Copper, Chromium and Zinc as an economical and effective way to create high-performance electrocatalysts for overall water splitting, providing a feasible route towards sustainable hydrogen production.