Defect-Rich Nitrogen Doped Co3O4/C Porous Nanocubes Enable High-Efficiency Bifunctional Oxygen Electrocatalysis

Heteroatom doping plays a significant role in optimizing the catalytic performance of electrocatalysts. However, research on heteroatom doped electrocatalysts with abundant defects and well-defined morphology remain a great challenge. Herein, a class of defect-engineered nitrogen-doped Co3O4 nanoparticles/nitrogen-doped carbon framework (N-Co3O4@NC) strongly coupled porous nanocubes, made using a zeolitic imidazolate framework-67 via a controllable N-doping strategy, is demonstrated for achieving remarkable oxygen evolution reaction (OER) catalysis. X-ray photoelectron spectroscopy, X-ray absorption fine structure, and electron spin resonance results clearly reveal the formation of a considerable amount of nitrogen dopants and oxygen vacancies in N-Co3O4@NC. The defect engineering of N-Co3O4@NC makes it exhibit an overpotential of only 266 mV to reach 10 mA cm(-2), a low Tafel slope of 54.9 mV dec(-1) and superior catalytic stability for OER, which is comparable to that of commercial RuO2. Density functional theory calculations indicate N-doping could promote catalytic activity via improving electronic conductivity, accelerating reaction kinetics, and optimizing the adsorption energy for intermediates of OER. Interestingly, N-Co3O4@NC also shows a superior oxygen reduction reaction activity, making it a bifunctional electrocatalyst for zinc-air batteries. The zinc-air battery with the N-Co3O4@NC cathode demonstrates superior efficiency and durability, showing the feasibility of N-Co3O4/NC in electrochemical energy devices.