Molecular Engineering toward Pyrrolic N‐Rich M‐N4 (M = Cr, Mn, Fe, Co, Cu) Single‐Atom Sites for Enhanced Heterogeneous Fenton‐Like Reaction

Abstract

Heterogeneous Fenton‐like reactions (HFLR) are promising alternative strategies to address the inherent limitations of the classic Fenton systems. Herein, a facile and scale‐up approach for the synthesis of transition metal single‐atom sites (SA‐TM, TM = Cr, Mn, Fe, Co, Cu) coordinated onto pyrrolic N‐rich g‐C 3 N 4 (PN‐g‐C 3 N 4) scaffold is developed. The regulated pyrrolic N‐rich SA‐TM catalytic sites exhibit excellent performances for HFLR. As a model of SA‐TM/PN‐g‐C 3 N 4, SA‐Cr/PN‐g‐C 3 N 4 is efficient for the catalytic oxidation of bisphenol A via HFLR under visible light with outstanding cyclic stability and wide effective pH range (3.0–11.0). The synergy of photocatalysis and single‐atom catalysis leads to accelerated production and separation of charge carriers as well as the cycling of Cr 3+/Cr 2+ couple, consequently boosting the performance in HFLR. Theoretical calculations indicate that the Cr(II)‐N 4 sites with the metalloporphyrin‐like structure are more reactive than the doped Cr(II) sites in the g‐C 3 N 4 matrix, which act as the peroxidase‐mimicking nanozyme for efficient and homolytic cleavage of peroxide OO in H 2 O 2. This study expands the family of the iron‐free Fenton‐like systems and provides new strategies to the rational design and precise regulation of on‐demand multifunctional single‐atom catalysts for advanced water remediation.