In-situ fabrication of N-doped iron-based Fenton-like catalyst (α-Fe2O3/N-CHCP) with superior activity toward methylene blue degradation

Abstract

Nitrogen doping serves as a viable strategy to improve the activity of heterogeneous Fenton-like catalysts, whereas the practical deployment of Fenton-like technology is restricted by the complexity of nitrogen-doping procedures. Herein, a in-situ nitrogen-doped Fenton-like catalyst was synthesized through calcination from an in-situ iron-incorporated hyper-cross-linked polymer, where aniline functions as both carbon and nitrogen source while FeCl3 serves dual roles as catalyst for the polymerization and iron precursor. The resulting α-Fe2O3/N-CHCP materials were systematically evaluated for methylene blue (MB) degradation via heterogeneous Fenton-like reactions. Comprehensive characterization demonstrates that nitrogen doping effectively modulates the electronic structure of the carbon matrix, facilitating enhanced charge transfer kinetics and promoting efficient ≡Fe3+/≡Fe2+ cycling for superior H2O2 activation. The optimized α-Fe2O3/N-CHCP-2 catalyst exhibits exceptional catalytic performance, achieving complete removal of MB (100 mg L−1) within 15 min under neutral conditions (pH 7.3) with a high apparent rate constant (kobs) of 0.4732 min−1 significantly surpassing the N-free α-Fe2O3/CHCP catalyst (kobs = 0.0159 min−1). The α-Fe2O3/N-CHCP-2 catalytic system also demonstrates remarkable operational flexibility, maintaining high efficiency across a broad pH range (3-10) and in the presence of some common inorganic coexisting ions. Mechanistic investigations, supported by quenching experiments and EPR spectroscopy, reveal that hydroxyl radicals (•OH) are the predominant reactive species, whereas superoxide radicals (•O2−) contribute secondarily to the degradation process. This work establishes an effective synthetic approach for constructing advanced in-situ N-doping and metal-nitrogen-carbon coordination systems with optimized interfacial electron transfer properties, offering promising applications in advanced oxidation processes for wastewater remediation.