Persulfate activation over B, N co-doped carbon nanotubes encapsulated with Fe3C (Fe3C@BN-CNT-x) studied for degradation of Rhodamine B

Herein, B, N co-doped carbon nanotubes encapsulated with Fe 3 C (Fe 3 C@BN-CNT-x) were synthesized via a one-step pyrolysis process, which is used to activate peroxymonosulfate (PMS) for the degradation and removal of water-soluble dye pollutants. The morphology and crystalline phase structure, elemental composition, specific surface area, pore structure, and defects of Fe 3 C@BN-CNT-x were subjected to comprehensive analysis and investigation through the use of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N 2 isothermal adsorption and desorption curves, Raman spectroscopy. Fe 3 C@BN-CNT-0.3, the best sample, displayed the largest specific surface area, the highest ratio of Fe-N x and BC 3 centers, and most abundant defect sites. As a result, Fe 3 C@BN-CNT-0.3 shows the fastest and highest efficient removal of Rhodamine B (RhB), achieving 100% degradation efficiency within 8 mins. The degradation rate constant of RhB over Fe 3 C@BN-CNT-0.3 is as high as 0.531 min -1 , which is about 5 times that of Fe 3 C@N-CNT. Free-radical quenching experiment and electron paramagnetic resonance (ESR) spectroscopy, as well as electrochemical voltammetry, identify the non-radical 1 O 2 as the dominant reactive species. Other free-radicals, such as SO 4 • − , •OH, and •O 2 − , play a minor role, while electron transfer mechanism was not a significant factor in the process of degradation. • B, N co-doped carbon nanotubes encapsulated with Fe 3 C (Fe 3 C@BN-CNT-x) were prepared by one-step pyrolysis process. • Fe 3 C@BN-CNT-0.3 displayed the largest specific surface area and most abundant defect sites. • Fe 3 C@BN-CNT-0.3 showed the fastest and most efficient removal of Rhodamine B (RhB), 100% degradation within 8 mins). • Non-radical 1 O 2 was identified as the dominant reactive species, while free radicals (SO 4 •- , •OH, and •O 2 - ) play a minor role. • The synergistic effect between Fe-N x centers and BC 3 sites may be the key to catalyzing PMS activation.