Unraveling the discriminative mechanisms for peroxy activation via atomically dispersed Fe-N5 sites for tunable water decontamination

The discriminative activities and mechanisms for activation of O-O bond in peroxy compounds via single-atom catalysts (SACs) especially with a higher coordination number (M-N5) are rarely explored. Herein, the atomic catalyst (Fe-SAC) with Fe-N5 as the active center was constructed, which could simultaneously and effectively activate peroxymonosulfate (PMS), peroxydisulfate (PDS), and hydrogen peroxide (H2O2). Density functional theory (DFT) calculations combined with experiments results demonstrated that the degradation efficiencies of acyclovir were corresponding to the changes of O-O bond length in various peroxy compounds. Meanwhile, the experiments exposed that the three oxidants all produced •OH, but the PMS also contained 1O2 and Fe(IV)=O, and PDS contained O2•- additively. The scale-up experiment showed Fe-SAC could operate steadily for nearly 7 d. Overall, this work unveils the discriminative mechanisms for activation of O-O band in different Fenton-like systems. Moreover, the Fe-SAC with high coordination numbers has excellent catalytic properties and practical performance.