Facile Pyrolysis Treatment for the Synthesis of Single-Atom Mn Catalysts Derived from a Hyperaccumulator

Advanced oxidation processes (AOPs) have re-vealed wide prospects in the application of the degradation of organic contaminants in ground water and soil. High-performance, environmentally friendly, and low-cost single-atom catalysts (SACs) are promising approaches to active persulfate in AOPs. However, the practical application of SACs is restricted by high preparation costs and tedious procedures. Herein, a manganese (Mn) hyperaccumulator, Phytolacca americana, was successfully exploited as a precursor to synthesize a novel Mn SAC (SPBC-700N) via a one-step pyrolysis method. In SPBC-700N, Mn atoms are dispersed atomically upon the carbon matrix and coordinate with four N atoms to form Mn-N4 active sites, which exhibits an extraordinary catalytic activity for peroxymonosulfate (PMS) activation. A large number of reactive oxygen species are formed during the reaction, and over 90% of the antibiotic (chloroquine phosphate/CQP) could be removed within 30 min. The superior catalytic performance of the Mn SAC/PMS system for CQP degradation is ascribed to the synergistic effect of the maximized utilization of Mn atoms and the neighboring pyrrolic N sites, as identified by X-ray absorption fine structure spectroscopy and density function theory calculations. This work not only provides a green and low-cost strategy for synthesizing SACs but also gives an atomic-level insight into the catalytic activity of the Mn-N4 sites for PMS activation.

Automated summary

High-performance, environmentally friendly, and low-cost single-atom catalysts (SACs) show great potential in the degradation of organic contaminants using peroxymonosulfate (PMS). A novel manganese single-atom catalyst (SPBC-700N) was successfully synthesized using Phytolacca americana as a precursor through one-step pyrolysis. The SPBC-700N exhibited extraordinary catalytic activity for PMS activation, leading to over 90% removal of chloroquine phosphate (CQP) within 30 minutes. The excellent catalytic performance of the Mn SAC/PMS system is attributed to the maximized utilization of manganese atoms and the synergistic effect with neighboring pyrrolic nitrogen sites.