Selective Introduction of Pentagon Defects into Co‐N ₄ Sites for Boosting Fenton‐Like Activity

Abstract Carbon‐supported single‐atom catalysts (CS‐SACs) have attracted tremendous attention in environmental remediation fields, however, the role of the ubiquitously existing carbon defects on the support in regulating the electronic structure of active metal sites has long been overlooked. Herein, a selective pyridinic N etching strategy is proposed to controllably fabricate specific pentagon defects in the carbon supports anchored with Co‐N 4 sites. Theoretical and experimental results reveal that the pentagon defects can induce upward shifting of the Co d‐band center and increase the electron density in the dxz and dz 2 orbitals, indicating its indispensable role in regulating the electronic structure of the metal center. As a result, efficient electron transfer is realized between the Co atom and peroxymonsulfate (PMS). Moreover, the energy barriers for crucial oxygen intermediate are reduced, which facilitates the generation of singlet oxygen ( 1 O 2 ). Consequently, the Co‐N 4 catalyst with pentagon defects (C5‐Co‐N 4 ) achieved a remarkable TOF value (9.37 min −1 ) in a Fenton‐like reaction, surpassing the state‐of‐the‐art single‐atom catalysts reported so far. This work not only provides a strategy to controllably fabricate specific defects in CS‐SACs but also deepens the fundamental understanding on how pentagon defects regulate the electron structure and catalytic performance of metal‐N 4 sites.