Boosted Oxygen Evolution Reactivity by Igniting Double Exchange Interaction in Spinel Oxides

A double-exchange interaction (DEI) was demonstrated to boost the oxygen evolution reaction (OER) in spinel oxides. DEI was ignited by synergistic actions of constructing nanoheterojunctions and creating oxygen vacancy (VO) in spinel NiCo₂O₄. DEI between octahedrally coordinated Ni and Co resulted in the generation of superior OER active centers Co(3-δ)+ and Ni³⁺. The multiple synergistic effects empower the electrocatalyst with exceptional OER activity, with an overpotential of 270 ± 3 mV at 10 mA/cm² and a Tafel slope of 39 mV/dec, both of which are among the best values for NiCo₂O₄-based nanostructures, and even better than those for IrO₂ and RuO₂.