A phosphorene-boride nanohybrid with dual-pathway periodate activation for water purification

Transition metal borides (TMBs) are attractive materials for advanced oxidation processes, but their practical use is hindered by limited stability and electron transport. Here, we synthesized a nanohybrid composed of amorphous Fe₃Co₇ boride anchored on exfoliated black phosphorus (Fe₃Co₇-B/EBP) via a facile chemical reduction method. The heterostructure facilitates strong interfacial electronic coupling and optimized adsorption of oxygenated intermediates, significantly boosting periodate activation. Crystalline EBP ensures high conductivity, while the amorphous Fe-Co boride contributes abundant catalytic sites and protects the support against oxidative degradation. Mechanistic studies, including electron paramagnetic resonance, radical scavenging, and electrochemical analyses, demonstrate a dual-pathway oxidation mechanism involving both radical (HO^·, O₂^⋅-) and non-radical (¹O₂, electron transfer) processes. Liquid chromatography-mass spectrometry further identifies key intermediates and tracks degradation pathways. Under near-neutral pH, the Fe₃Co₇-B/EBP+PI system achieves 90-99 % removal of representative chlorophenols and phenolics-2,4-dichlorophenol, 4-chlorophenol, bisphenol A, and phenol-each at an initial concentration of 10 mg L⁻¹ . In a continuous-flow reactor, Fe₃Co₇-B/EBP retains over 94.3 % efficiency for 168 h under flow conditions, demonstrating robust stability and scalability. This work presents a durable, recyclable, and scalable TMB-phosphorene hybrid for sustainable water purification.