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‐C3N4 (PN‐g‐C3N4) 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‐C3N4, SA‐Cr/PN‐g‐C3N4 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 Cr3+/Cr2+ couple, consequently boosting the performance in HFLR. Theoretical calculations indicate that the Cr(II)‐N4 sites with the metalloporphyrin‐like structure are more reactive than the doped Cr(II) sites in the g‐C3N4 matrix, which act as the peroxidase‐mimicking nanozyme for efficient and homolytic cleavage of peroxide OO in H2O2. 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.

Atomically Dispersed Cu Nanozyme with Intensive Ascorbate Peroxidase Mimic Activity Capable of Alleviating ROS‐Mediated Oxidation Damage

“…Besides, the majority of the bright spots are below 0.2 nm in diameter (Figure S4 , Supporting Information), demonstrating that Cu elements were uniformly distributed over the CN matrix as single atoms. [ 12 , 19 , 27 ] Meanwhile, no discernable bulk‐like crystalline copper species are founded in XRD patterns or Fourier transform infrared (FTIR) spectroscopy (Figure S5 , Supporting Information), further proving the atomic distribution of Cu atoms. The Brunauer–Emmett–Teller (BET) measurements in Figure S6 (Supporting Information) further manifest that Cu SAs/CN possessed a porous structure with a large surface area compared with CN, which is conducive to exposure the Cu active sites.…”

“…Nanozyme defines a generation of nanomaterials with enzyme‐like behavior. [ 10 , 11 , 12 ] It combines the advantages of nanomaterials (easy preparation, low cost for scale‐up, and especially high stability) that catalyze biochemical reactions under ambient conditions. [ 13 , 14 , 15 , 16 ] In particular, the single‐atom nanozymes with atomically dispersed active metal centers are recently considered as a novel frontier due to their maximum utilization efficiency of metal atoms and high activity.…”

Accelerating FeIII-Aqua Complex Reduction in an Efficient Solid–Liquid-Interfacial Fenton Reaction over the Mn–CNH Co-catalyst at Near-Neutral pH

“…The concentration of H 2 O 2 is detected using a titanium­(IV) colorimetric method . Quenching experiments are tested by adding 0.05 mmol of carotene, p -benzoquinone (BQ), isopropanol (IPA), K 2 Cr 2 O 7 , or ethylenediaminetetraacetic acid (EDTA)-2Na to evaluate the possible contributions of 1 O 2 , • O 2 – , • OH, photogenerated electrons (e – ), and photogenerated holes (h + ) in the degradation process . The ROS are reflected by electron paramagnetic resonance spectroscopy (EPR, Bruker A200) with 5 mM 5,5-dimethyl-1-pyrroline- N -oxide (DMPO) in methanol and water as • OH and • O 2 – trapper.…”

Recent Developments of Microenvironment Engineering of Single‐Atom Catalysts for Oxygen Reduction toward Desired Activity and Selectivity

“…[87][88][89][90] A variety of SACs with high metal mass loading for efficient and highly selective ORR and their relevant applications have been summarized on several reviews. [91][92][93][94] However, a few timely summaries conclude the ORR mechanism paths on SACs and emphasize the microenvironment regulation of SAAS for ORR with ideal activity and selectivity. Therefore, this review will mainly elucidate the ORR mechanisms on SAAS and review the recent discovery for tuning the microenvironment of carbon-and noncarbon-supported SACs toward efficient ORR via 4e − or 2e − process, as well as the recently reported technical methods for production and improvement of SACs.…”