Atomically Fe doped hollow mesoporous carbon spheres for peroxymonosulfate mediated advanced oxidation processes with a dual activation pathway

PMS-based advanced oxidation processes (AOPs) are a high-efficiency and economically favorable approach for dealing with aqueous organic pollutants. In this work, an Fe single-atom catalyst deposited on N-doped hollow mesoporous carbon spheres (Fe-NC HMCS) is prepared via an in situ hard-template strategy and used to activate peroxymonosulfate (PMS) for organic pollutant degradation. Benefiting from the presence of Fe-N sites and a suitable structure (a large specific surface area and a uniform mesoporous structure), the obtained Fe-NC HMCS catalyst with a low Fe-loading capacity (0.16 wt%) exhibits an outstanding turnover frequency (TOF) as high as 55.4 min(-1) during the degradation of bisphenol A (BPA). Remarkably, the introduction of atomically dispersed Fe atoms can successfully modulate the pathway of PMS activation, and the radical-mediated process of PMS activation accelerated by graphitic N is attenuated, in turn boosting electron-transfer-mediated nonradical processes. This work provides an ingenious strategy for designing highly efficient and selective single-atom catalysts and reveals the corresponding activation mechanism for PMS-based AOPs.