NiFe Alloy Nanocrystals Anchored on Nitrogen-doped Carbon: Interface Engineering for Enhanced Peroxymonosulfate Activation via Non-radical Pathways

Abstract

Peroxymonosulfate (PMS) activation based on non-radical oxidation has emerged as a highly efficient and feasible strategy for wastewater treatment. Herein, heterogeneous catalysts with NiFe alloy nanocrystals anchored on nitrogen-doped carbon (NiFe-N-C) were rationally designed and fabricated to activate PMS for the degradation of tetracycline (TC). The NiFe-N-C/PMS catalytic system achieved 93.3% TC removal and 79.8% PMS utilization within 60 minutes, outperforming analogous catalystic systems reported. Notably, the system exhibited strong anti-interference against various anions and humic acid (HA), and maintained high catalytic activity over a broad pH range, highlighting its strong adaptability to complex practical water environments. Singlet oxygen ( 1 O2) and high-valent metal species (HVMSs) were identified as the dominant oxidants for TC degradation. DFT calculations further revealed that the Ni/Fe dual active sites serve as the dominant catalytic centers in NiFe-N─C, which not only reduce the energy barrier for O-O bond cleavage of PMS to facilitate the formation of NiFe Ⅳ =O species, but also preferentially promote PMS oxidation to generate SO5• -which is critical in the generation of 1 O2. The N-C matrix stabilizes NiFe alloy nanocrystals through the formation of strong surface N-M bonds, while enabling rapid interfacial electron transfer in the catalytic system. Comprehensive analyses of degradation pathways and toxicity evaluations confirmed the environmental safety of the catalytic process. This study provides a theoretical basis for high-performance non-radical catalytic system design and lays a foundation for their practical application in water pollution control.