Mechanistic pathways for the degradation of SMX drug and floatation of degraded products using F–Pt co-doped TiO2 photocatalysts

Abstract

This work presents smart pathways to enhance the photocatalytic activity of TiO₂ via co-doping with fluorine (F) and platinum (Pt) to form F–Pt co-doped TiO₂ photocatalysts and investigates the unique and unusual fluorination of the floated products. Our investigations indicate that the crystalline structure of the photocatalysts was a mixture of anatase and brookite phases and that the nanoparticles of the synthesized nanocomposites had nanometric sizes (4–25 nm). The F–Pt co-doped TiO₂ nano-photocatalysts demonstrated degradation of sulfamethoxazole (SMX) drug of >93% within 90 min under direct solar light and 58% degradation within 360 min under a solar simulator. Thus, co-doping TiO₂ with F and Pt atoms to form F–Pt co-doped TiO₂ nanocomposite is an efficient pathway to achieve high photocatalytic performance escorted with the formation of floating metal-fluoropolymer, unlike pristine TiO₂ which has less photocatalytic degradation and no generation of a floating polymer. Our photocatalytic protocol demonstrates that the degradation of SMX started with redox reactions of oxygen and water absorbed on the surface of the prepared nanocomposites to form superoxide anions (O₂˙⁻) and hydroxy radicals (˙OH) which have oxidation superpower. The resultant products were subsequently fluorinated by fluoride radical ions and floated as metal-fluoropolymer.