Ti3+ self-doped TiO2 anchored with iron oxide quantum dots as an efficient persulfate catalyst for the enhanced removal of typical phenolic pollutants from water under visible light

Abstract

In this work, a facile impregnation–calcination route was proposed for the synthesis of Ti3+ self−doped TiO2 anchored with iron oxide quantum dots (FeQDs/TiO2−x) as an efficient visible light−derived persulfate catalyst for organic degradation. After the successful co−doping of Fe3+ and Ti3+, the obtained FeQDs/TiO2−x exhibited quasi−full visible light absorption, with the maximum absorption edge broadened to 791 nm; furthermore, its charge separation and interfacial transport capacity were significantly enhanced, as evidenced by the fact that the lifetime of the photogenerated electrons was prolonged from 6.17 to 10.34 ns. In addition, the surface Fe3+ species on FeQDs/TiO2−x can be effectively reduced to Fe2+ by the separated electrons, establishing an efficient cycle between Fe3+ and Fe2+. Therefore, the obtained FeQDs/TiO2−x nanocomposite exhibited enhanced catalytic performance for the degradation of phenolic pollutants via PS activation under visible light. Specifically, 50 mg/L bisphenol A (BPA) and acetaminophen (AAP) can be completely degraded by FeQDs/TiO2−x with faster reaction rate constants and higher mineralization rates compared to its counterparts, including TiO2, TiO2−x, and FeQDs/TiO2. Based on the results of material characterization, degradation experiments, identification of reactive oxidizing species, and chemical quenching experiments, the mechanism of the enhanced photocatalytic activity of FeQDs/TiO2−x was elucidated. Our results demonstrated the high potential of FeQDs/TiO2−x for wastewater treatment.