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 Co 3 O 4 nanoparticles/nitrogen-doped carbon framework (N-Co 3 O 4 @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-Co 3 O 4 @NC. The defect engineering of N-Co 3 O 4 @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 RuO 2 . 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-Co 3 O 4 @ 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-Co 3 O 4 @NC cathode demonstrates superior efficiency and durability, showing the feasibility of N-Co 3 O 4 /NC in electrochemical energy devices.

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A monoclinic BiVO 4 film was grown on a transparent conducting substrate for photoelectrochemical oxidation of water. A photocurrent up to 2.3 mA cm −2 under visible light (λ > 420 nm) was achieved after treating the sample simply by electrochemical reduction followed by NaBH 4 . The high photocurrent is believed to be due to the improved carrier separation and transportation as a result of increased donor density. † Electronic supplementary information (ESI) available: Detailed information for experiment and XPS spectra. See

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