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 (V-o) in spinel NiCo2O4. DEI between octahedrally coordinated Ni and Co resulted in the generation of superior OER active centers Co(3-delta)+ and Ni3+. The multiple synergistic effects empower the electrocatalyst with exceptional OER activity, with an overpotential of 270 +/- 3 mV at 10 mA/cm(2) 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.