Interfacial electron transfer in Co Fe catalysts drives self-sustained tetracycline degradation and radical enhancement in low-oxidant system

Advanced water treatment technologies face significant challenges due to high oxidant dependency and limited catalyst efficiency. To address this, we constructed a Co Fe bimetallic biochar composite (Co1Fe1/3BC) featuring both oxidant-minimized operation and self-sustaining catalytic functionality. This material was synthesized via low-temperature pyrolysis, deriving form wheat straw biomass. TEM, XRD and XPS analyses uncovered a Co Fe electron transfer channel and confirmed the superiority of Co-O-Fe active sites. The system achieved efficient tetracycline (TC) degradation (>99 % removal within 10 min, k obs = 0.3422 min −1 ) at low oxidant concentration (0.2 mM PMS) while significantly enhancing PMS utilization efficiency compared to single-metal catalysts. Crucially, the catalyst demonstrated intrinsic self-driven degradation capability without PMS, maintaining 56.7 % pollutant removal after four cycles. LC-MS analysis verified persistent self-driven functionality alongside >90 % stability in complex aqueous matrices. In the radical-dominated pathway, • OH played the main role, and the bimetallic site regulated electron transfer to promote the synergistic effect of non-radical pathways ( 1 O 2 ) and radical pathways. This work establishes a design principle for dual-functional catalytic materials in sustainable water remediation and advances fundamental mechanistic insights into electron-transfer-driven advanced oxidation processes. • Bimetallic catalyst was synthesized from biomass through low-temperature pyrolysis. • Electron transfer across Co-O-Fe interfaces directly degraded organic pollutants. • Efficient contaminant destruction and environmental adaptability. • 99.8 % TC removal efficiency within 10 min using low-dosage oxidant.