Nitrogen and Fluorine Codoped, Colloidal TiO2 Nanoparticle: Tunable Doping, Large Red-Shifted Band Edge, Visible Light Induced Photocatalysis, and Cell Death.

Visible light photocatalysis by TiO2 requires efficient doping of other elements with red-shifted band edge to the visible region. However, preparation of such TiO2 with tunable doping is challenging. Here we report a method of making nitrogen (N) and fluorine (F) codoped TiO2 nanoparticle with tunable doping between 1 and 7 at. %. The preparation of N, F codoped TiO2 nanoparticle involves reaction of colloidal TiO2 nanorods with an ammonium fluoride-urea mixture at 300 °C, and the extent of N/F doping is tuned by varying the amount of ammonium fluoride-urea and the reaction time. Resultant colloidal N, F codoped TiO2 nanoparticles show doping dependent shifting of the band edge from the UV to near-IR region, visible light induced generation of reactive oxygen species (ROS), and visible light photodegradation of bisphenol A. A colloidal form of doped TiO2 nanoparticle offers labeling of cells, visible light induced ROS generation inside a cell, and successive cell death. This work shows the potential advantage of anisotropic nanoparticle precursor for tunable doping and colloidal form of N, F codoped TiO2 nanoparticle as a visible light photocatalyst.