Oxygen-vacancy-enriched substrate-less SnO<inf>x</inf>/La-Sb anode for high-performance electrocatalytic oxidation of antibiotics in wastewater

Abstract

Electrocatalytic oxidation is a promising technology for treating toxic organic pollutants in water and wastewater, but conventional Ti-based anodes often exhibit a short service life and low efficiency in application. Oxygen vacancy (OV)-based defect engineering is an effective activation method for enhancing the electrocatalytic activity of electrodes. Herein, the controllable formation of OV on the surface of a freestanding SnO2-Sb anode was achieved by the quantitative doping of La3+ into the SnO2 crystal structure of the anode for high-performance electrochemical wastewater treatment. The resultant SnOx/La-Sb anode degraded nearly 100% moxifloxacin (MOX, 10 mg L−1) in 30 min, with a low energy consumption of 0.09 kWh m−3. The SnOx/La-Sb anode with an OV density of 1.09% had the highest degradation rate constant (0.226 min−1), 8 times higher than that of the SnO2-Sb anode and 16 times higher than that of the state-of-the-art boron-doped diamond anode. La3+ doping-induced OV activated the anode surface for electrochemical reactions by boosting the interfacial electron transfer and •OH generation (103% increase). The novel 3D permeable SnOx/La-Sb anode also exhibited remarkable stability (predicted service life of 59 years) and high-rate performance (>98%) in a continuous flow-through treatment system (<1 min through the anode).