Sulfur-doped porous carbon sheets embedded with rich iron sites for 1O2 dominated peroxymonosulfate activation

Abstract

The poor anti-interference ability of radical-dominated processes continues to be a hindrance to the effectiveness of purification and the practical use of peroxymonosulfate-based advanced oxidation processes (PMS-AOPs). Herein, iron, nitrogen, and sulfur co-doped porous carbon sheets (Fe–SNC) were successfully synthesized via a one-step pyrolysis process by adopting Mohr's salt and ZIF-8 sheets as precursors to efficiently activate PMS. Quenching experiments and electron paramagnetic resonance (EPR) characterization indicated that singlet oxygen (¹O₂) played the most important role in phenol degradation. Based on the variation in the material structure and density functional theory (DFT) calculations, the study revealed the specific mechanism of sulfur embedded in rich Fe₃C, Fe₄N, and Fe–Nx catalytic sites as an activator of PMS in the degradation of the pollutant of interest. In addition, S-doping sites were shown to shorten the distance between PMS and the catalyst due to electron polarization of the catalyst surface, which facilitated PMS adsorption. According to ultra-high-resolution electrospray time-of-flight mass spectrometry and the predictions of ECOSAR software, the aquatic ecological environment would not be harmed by degradation intermediates. As a consequence, this heterogeneous system possesses admirable anti-interference in pollutant elimination. These conclusions provide instructions for the creation of S-doped porous carbon sheets for effective water treatment.