An Active Hybrid Electrocatalyst with Synergized Pyridinic Nitrogen-Cobalt and Oxygen Vacancies for Bifunctional Oxygen Reduction and Evolution

Main observation and conclusion A hybrid bifunctional oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) NiCo2O4-x/NLG with rich pyridinic-nitrogen- cobalt coordination and oxygen vacancies was synthesized via a combination of the hydrothermal method and pulsed laser irradiation. NiCo2O4-x/NLG exhibits an excellent catalytic activity with a low overpotential of 290 mV at 10 mA center dot cm(-2) for OER and a high half-wave potential of 0.85 V for ORR. As a result, the overall ORR/OER overpotential of NiCo2O4-x/NLG is only 0.67 V in 1.0 mol/L KOH electrolyte, which is superior to commercial noble-metal-based catalysts (Pt/C+RuO2). It is evidenced that the enhanced intrinsic OER and ORR activities of NiCo2O4-x/NLG are attributed to a synergistic effect between the pyridinic-N-Co coordination and the oxygen vacancies. This work provides a new design strategy for enhancing the intrinsic activity of bifunctional ORR/OER electrocatalysts.