An Unsaturated Bond Strategy to Regulate Active Centers of Metal‐Free Covalent Organic Frameworks for Efficient Oxygen Reduction

Abstract

Unsaturated environment is the key to affect catalytic activity of the oxygen reduction reaction (ORR). Unveiling the effect of unsaturated sites toward ORR activity is of importance due to the vague unsaturated states. Reported here is a proof-of-concept strategy on the evaluation of unsaturated bonds (UBs) on adjacent carbon environment by precisely developing two metal-free vinyl-/azo-decorated covalent organic frameworks (Vinyl-COF and Azo-COF) as catalysts. The as-prepared UB-COFs exhibit good performance than the control Py-COF and comparable to the most reported carbon catalysts. Supported by theory calculations and in situ Raman spectra-electrochemistry, it is revealed that the UBs in organic catalysts can produce para-activation, identifying the para C=N groups as active centers. Importantly, the intrinsic UBs can induce local charge redistribution, and make the molecular skeleton possess high isosurface map distribution, with an efficient affinity for oxygen intermediates.

Construction of imide‐linked covalent organic frameworks with palladium nanoparticles for oxygen reduction reaction

“…33 Yan et al has developed two metal-free azo-/vinyl-decorated COFs linked by unsaturated bonds toward as efficient ORR electrocatalysts. 34 Furthermore, by introducing methyl groups into the biphenyl-based COFs, the band gap has been effectively modulated and the intermediate adsorption has been enhanced, then the ORR process has been improved. 35 To enhance the catalytic activity, different heteroatoms have been developed.…”