Redox‐Active Radical Covalent Organic Frameworks as Highly Efficient Metal‐Free Electrocatalysts for 4e ⁻ Oxygen Reduction

The strategic incorporation of open‐shell radicals into covalent organic frameworks (COFs) represents a promising yet underexplored avenue for designing metal‐free oxygen reduction reaction (ORR) electrocatalysts. Moving beyond conventional closed‐shell linker engineering, we present a one‐step multivariate synthesis to precisely install 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) radicals within a crystalline COF skeleton. The resulting radical‐embedded TPET‐TEMPO COF exhibits superior four‐electron (4e − ) ORR activity, evidenced by an electron transfer number of 3.95 and a minimal H 2 O 2 yield of 8.8% (at 0.25 V vs. RHE), considerably outperforming the radical‐free TPET analogue. Mechanistic studies using density functional theory (DFT) calculations attribute this performance to the TEMPO radicals functioning as an intrinsic electron shuttle, which lowers the activation barriers for ORR, in agreement with experimental observations. Practical viability of TPET‐TEMPO is demonstrated in a rechargeable zinc‐air battery (ZAB), where TPET‐TEMPO as the cathode catalyst delivers a peak power density of 148.4 mW cm −2 . This work highlights the critical role of radical motifs as active vertices and outlines a facile blueprint for constructing radical‐bearing COFs for efficient energy applications.