Selective radical pathways on defect-engineered electrophilic biochar for sustainable water purification

Traditional advanced oxidation processes are frequently hindered by limited efficiency in complex wastewater, primarily due to the short lifetime and nonselective nature of hydroxyl radicals (•OH). While peracetic acid activation involves competing nucleophilic and electrophilic pathways, selectively channeling this process toward the acetylperoxyl radical (CH₃C(O)OO•)-mediated electrophilic route remains a formidable challenge. Here, we report a universal nitrogen-removal strategy to engineer 5-14-5 vacancy-pentagon defects in nitrogen-containing agro-forestry biomass-derived biochar. These vacancy-based topological defects reconfigure the electronic landscape by downshifting the Fermi level and upshifting the p-band center. This electronic modulation transforms the carbon framework from a traditional electron donor into a potent electrophilic sink with a superior electron accepting capacity (EAC = 3.77 mmol·e^-·g^-1). This reconfiguration renders the electrophilic pathway thermodynamically favorable (ΔG = - 0.09 eV), achieving near-total selectivity (> 99%) for CH₃C(O)OO• over •OH. More importantly, this system delivers a high normalized kinetic constant (409.82 min^-1 M^-1) and sustains high-flux radical production over 260 hours of continuous operation. Furthermore, life-cycle assessment validates its environmental sustainability, highlighting a net-negative carbon footprint. This study provides fundamental insights into defect-mediated radical chemistry and offers a scalable, sustainable paradigm for precision water decontamination.