Fe3O4 nanoparticles encapsulated in boron nitride support via N-doped carbon layer as a peroxymonosulfate activator for pollutant degradation: Important role of metal boosted C-N sites

Developing highly efficient and stable catalysts for peroxymonosulfate (PMS) based advanced oxidation pro-cesses (AOPs) are crucial in the field of environmental remediation. In this work, a facile encapsulated-precursor pyrolysis strategy was reported to prepare a competent PMS-activation catalyst, in which uniformly distributed Fe3O4 nanoparticles were firmly anchored on porous boron nitride (BN) nanosheets by N-doped carbon shell (NC layer). Taking advantage of strong metal-support interaction, the as-synthesized catalyst (BFA-500) could effi-ciently activate PMS to achieve 100% removal of 4-chlorophenol (4-CP) in 6 min, and the corresponding turnover frequency (TOF) value was 1-2 orders of magnitude higher than that of the benchmark homogeneous (Fe2+) and nanoparticle (Fe-0 and Fe3O4) catalysts. Moreover, the well protected encapsulated structure of BFA-500 ensured the remarkable stability that could effectively resist the interference of complex water environment, including initial pH value, various inorganic ions and actual water, and its catalytic activity remained almost unchanged in 5 use-regeneration cycles. More importantly, the generation of O-2(.-) and O-1(2) radicals for the 4-CP removal in BFA-500/PMS system was ascribed to Fe3O4 boosted C-N sites containing pyridinic N, where elec-trons transferred from the embedded Fe3O4 nanoparticles to C-N sites to secure the PMS dissociation into reactive radicals. Overall, this work provided a promising way to design desired PMS-activation catalyst toward wastewater purification.

Automated summary

This study reported a method for preparing highly efficient PMS-activation catalyst using an encapsulated-precursor pyrolysis strategy. The catalyst consisted of uniformly distributed Fe3O4 nanoparticles and a well protected encapsulated structure, which allowed for efficient activation of PMS and complete removal of organic pollutants in a short time. Furthermore, the catalyst exhibited excellent stability and could resist interference from complex water environments, with its catalytic activity remaining almost unchanged after multiple uses and regenerations.