Redox-Active Cr3+ Dopants Stabilize NiFe2O4 Catalysts During High-Current-Density Oxygen Evolution

Hydrogen obtained via water electrolysis by using green power is clean energy for oursustainable development. However, the oxygen evolution reaction (OER) on the counter reactionremains a greater challenge due to the high overpotential and serious corrosion. Aiming to obtainelectrocatalysts with high activity and stability at high current densities, herein, Cr was introducedinto NiFeOx to form NiFe2-xCrxO4 on nickel foam (NF) through a straightforward synthetic approach.The NiFe2-xCrxO4 electrode performed high activity at 1.5 A cm-2 with an overpotential of 393 mVand stable operation for 200 hours at 1000 mA cm-2. The DFT simulations reveal the Cr-enhancedpolarization of oxygen species and the modulation of electron state enabling the electrocatalyst towithstand at a higher potential. The NiFe2-xCrxO4 ||Ni water electrolyzer operated stably over 2400hours at 1000 mA cm-2 and at higher current densities (2000-10000 mA cm-2) over 100 hours.Incorporating of Cr into NiFeOx enhances the electrochemical activity and long-term stability of theelectrodes, thereby providing valuable insights for the design and fabrication of high-performanceand durable anodes.Keywords: NiFexCr2-xO4, stability, Cr cation, oxygen evolution reaction, high current density.