Crystallinity-Induced Interfacial Electron Rearrangement Enables Ultrafast Fenton-Like Redox Cycling

The sluggish Fe(III)/Fe(II) redox cycle fundamentally constrains the efficiency of Fenton-based advanced oxidation processes. Herein, we report a crystallinity engineering strategy on red phosphorus (RP) co-catalysts to modulate interfacial P–Fe electronic interactions and unlock exceptional co-catalytic performance. The moderately crystalline C–P-6 exhibits optimal volcano-type activity, achieving an ofloxacin degradation rate constant of 0.52 min–1, which is 14.4-fold higher than the pristine Fe(III)/H2O2 system and approximately 2.2-fold higher than the unmodified RP. Mechanistic studies reveal that the long-range ordered lattice of crystalline RP constructs continuous electron transport channels, which, together with stable P–Fe interfacial coordination bridges, enable synergistic dual-pathway mechanism. Critically, density functional theory calculations and X-ray Absorption Fine Structure analysis confirm that crystalline P upshift the Fe 3d d-band center and substantially enhanced Fe 3d-O 2p orbital hybridization, facilitating efficient electron donation from P to Fe. Consequently, the C–P-6 system generates 15 times higher ·OH concentration than the pristine Fe(III)/H2O2 system (1.3-fold higher than unmodified RP, dominant reactive species), while exhibiting excellent anion tolerance, robust reusability, neutral pH adaptability, and reduced product toxicity. This work provides molecular-level insights into utilizing crystallinity-driven orbital engineering for the efficient detoxification of hazardous pollutants.