Enhanced visible-light absorption and dopant distribution of iodine-TiO2 nanoparticles synthesized by a new facile two-step hydrothermal method

In order to prepare visible-light responsive iodine-doped TiO2, a new facile synthetic approach was proposed, which started with the cost-efficient and environmentally friendly precursor of undoped anatase TiO2 to form nanotube structures as templates that collapsed and recrystallized into I-TiO2 nanopowders in HIO3 solution, followed by annealing at different temperatures. The modification of TiO2 to incorporate iodine and form titanium dioxide with significantly enhanced absorption in the visible range of the spectrum was investigated. The extent of iodine dopant incorporation was determined by X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray analysis (EDX) and was found to be homogenously distributed on each nanostructure as determined by electron energy-loss spectroscopy (EELS) elemental mapping and EDX spectroscopy. The modified TiO2 exhibits a dramatically extended absorption edge beyond 800 nm as compared to the original and unmodified TiO2.