Self-dispersed Fe single-atom anchored biochar derived from hyperaccumulator residues with intrinsic Zn and Fe for selective peroxymonosulfate activation via electron transfer process

The green synthesis and sustainable environmental applications of single atom catalysts (SACs) has attracted significant attention and emerged as a forefront of research. Herein, "self-dispersion" Fe single-atom anchored biochar (FeSA-BC) was facilely synthesized by endogenous strategy using hyperaccumulator residues (Sedum alfredii) with intrinsic Zn and Fe. Evaporation of hyper-enriched Zn during high temperature pyrolysis facilitated the formation of defect trapping sites and promoted the atomically-dispersion of intrinsic Fe. FeSA-BC exhibited an impressive mass activity of 3.13 × 104 min−1 mol−1 and excellent PMS utilization, and performed stable Bisphenol A (BPA) removal efficiency with high catalytic ability over a wide pH range and in the presence of groundwater interferences, including inorganic anions and natural organic matter. FeSA-BC/peroxymonosulfate (PMS) system enabled the potential difference-driven selective oxidation of electron-rich phenolic pollutants with relatively low ionization potential (IP) via nonradical process (EIP, < 7.0 eV), which is confirmed by the high correlation (R2 = 0.977) between Inkobs and IP. Theoretical calculation revealed that Fe-N3O1 site in FeSA-BC optimized the electronic properties and narrowed the energy gap, facilitating the selective electron transfer from pollutants to the FeSA-BC/PMS* complex. Effective remediation of polluted groundwater by vertical continuous-flow FeSA-BC/sand column further validated its practical application potential. This study opens a new avenue for upcycling of biomass wastes and green synthesis strategies of SACs, and provides inspiration for further research on sustainable environmental remediation.