Hydrothermal synthesis of LaSb co-doped Ti/SnO2 for removal of low-concentration ofloxacin: Mechanisms, DFT calculation, degradation pathway and toxicity evolution

SnO 2 anodes for electrochemical oxidation of persistent antibiotics are severely limited by rapid passivation, grain coarsening, and poor charge transfer. Herein, a novel La Sb co-doped Ti/SnO 2 anode was systematically engineered via a combined hydrothermal and thermal oxidation approach to concurrently address the structural stability and conductivity trade-offs. La 3+ segregates at grain boundaries, suppressing grain growth and eliminating microcracks. Sb doping introduces donor-type electronic states and improves coating conductivity. Consequently, the optimized La Sb co-doped anode exhibits exceptional electrocatalytic activity toward low-concentration ofloxacin (OFL) removal, obeying pseudo-first-order kinetics. Quenching tests and electron paramagnetic resonance (EPR) spectroscopy confirm that the degradation is co-driven by hydroxyl radicals (*OH), superoxide radicals (O 2 ⁎- ) and singlet oxygen ( 1 O 2 ), facilitated by the elevated surface chemisorbed oxygen (O ads ) ratio. Crucially, the optimized anode achieves a remarkable electrical energy per order (EE/O) of 2.64 kWh·m −3 ·order −1 along with robust electrochemical durability. Density functional theory (DFT) calculations predict the preferential reactive sites of OFL molecules. UPLC-MS detects intermediate parent-ion signals. Combined with DFT simulation and published literature, a tentative degradation pathway is proposed, while aquatic toxicity evaluation verifies the system can ultimately convert toxic intermediates into low-toxic products. This work provides a scalable fabrication strategy and comprehensive mechanistic insights for high-stability mixed metal oxide anodes toward advanced trace antibiotic wastewater purification.