Bio-porphyrin supported single-atom iron catalyst boosting peroxymonosulfate activation for pollutants degradation: A Singlet Oxygen-dominated nonradical pathway

Simultaneous modulation of the coordination environment of single-atom catalysts (SACs) and the construction of architectures with optimized exposed active sites are effective strategies to boost peroxymonosulfate (PMS) activation. Herein, the single-atom Fe supported on bio-sourced porphyrin-based porous active carbon (Fe-PAC) was reported with high porosity and abundant active sites. In particular, Fe-PAC showed high adsorption capacity (1892.7 mg g−1) and enhanced PMS activation for degrading 96.1 % sulfamethazine (SMT) even in complicated environmental interference. The reactive oxygen species analytic experiments revealed that the Fe-PAC achieved high 1O2 generation selectivity by activating PMS, which was confirmed by density functional theory (DFT) calculations results. The single Fe atoms were verified to serve as the dominant sites to activate PMS via the single O of SO42-, yielding 1O2 through pathway PMS → OH* → O* → OOH* → 1O2. Therefore, the Fe-sites-generated 1O2 could directly degrade the N-coordination sphere-adsorbed and pore-filling SMT with enhanced decontamination efficiency. This study sheds new insights on PMS activation mechanisms over single-atom metals-carbonaceous materials, thus promote its application for environmental remediation.