Fe/Mo bimetallic sites-decorated carbonaceous material via 3 electron photocatalytic oxygen reduction reaction pathway for ultra-efficient degradation of water pollutants

Photocatalytic three-electron oxygen reduction (3e - ORR) can convert dissolved O 2 into •OH via coupled 2e - /1e - steps, bypassing external H 2 O 2 dosing and the kinetic bottleneck of conventional photo-self-Fenton (PSF) systems. Here, Fe-substituted phosphomolybdate clusters (FePMo) are anchored on a biomass-derived hierarchical tubular carbon (HTCC) to form an HTCC/FePMo heterojunction (HFe) that drives a visible-light self-Fenton process. For tetracycline (TC, 10 mg L −1 ), HFe achieves 99 % removal within 120 min at unadjusted pH 0 = 5.8 ( k obs = 0.026 min −1 ) and 3.6–7.7-fold higher mineralization than either component, while retaining high activity from pH 3–9 and in saline water, natural surface water, and secondary effluent. In a continuous-flow reactor, an HFe/PVDF membrane (0.64 mg cm −2 loading; 2 mL min −1 , HRT 1.23 min) sustains > 90 % TC removal for 120 h. Ecotoxicity is alleviated, with inhibition-zone diameters shrinking from ∼2.3 to ∼0.8 cm ( S. aureus ) and from ∼1.25 to ∼0.7 cm ( E. coli ), and wheat-leaf Fv/Fm recovering to ∼0.73, comparable to the water control. The energy demand is low (EE/O = 0.0031 kWh L −1 ; EE/M = 0.31 kWh g −1 ), supporting a scalable, sustainable route for advanced treatment of refractory wastewater.