Nitrogen, phosphorus, and sulfur tri-doped hollow carbon shells derived from ZIF-67@poly (cyclotriphosphazene-co-4, 4′-sulfonyldiphenol) as a robust catalyst of peroxymonosulfate activation for degradation of bisphenol A

Abstract Heteroatom-doped carbon materials have emerged as attractive catalysts for peroxymonosulfate (PMS) activation and environment remediation recently due to its low cost and non-toxicity. In this study, novel N, P, and S tri-doped hollow carbon shells (NPSC) are elaborately fabricated using ZIF-67 and poly (cyclotriphosphazene–co-4,4′- sulfonyldiphenol) (PZS) as precursors. NPSC obtained at 700 °C shows better performance than those at other temperature (600 and 800 °C), and it can effectively degrade 90.1% of Bisphenol A (BPA) in the presence of PMS, which totally exceeds the performance of several common catalysts. It is found that for used catalyst, surface oxidation of carbon networks and blockage of heteroatom-doping active sites are two main reasons for the deterioration of reusability. Electron paramagnetic resonance (EPR) measurements and radical quenching tests are conducted to reveal that hydroxyl, sulfate, and superoxide radicals are main reactive species for BPA degradation in NPSC/PMS systems. Finally, it is proposed that synergistic effects of N, P, and S doping may greatly break the electroneutrality of pristine carbon structures, promote the O-O breakage of PMS, and facilitate the generation of radicals. Such findings dedicate to enlighten new thoughts and deeper understanding for synthesis of heteroatom-doped porous carbon in PMS activation.