Structural and optical properties of Fe@C doped TiO2 thin films prepared by sol–gel method

TiO2 is a widely used semiconductor photocatalyst, but its poor absorption of visible light and wide band gap (3.2 eV) limit its sunlight absorption efficiency. TiO2 is commonly modified through doping to reduce its forbidden band gap width and improve its sunlight absorption efficiency. Currently, researchers mainly modify TiO2 with metals or nonmetals, but no one has explored the use of nanoparticles with a magnetic nonmetal carbon layer coated with metal to study the optical properties of TiO2. In this study, we aim to modify the optical properties of TiO2 by incorporating the unique carbon shell nanoparticle structure into TiO2. Therefore, in this paper, magnetic carbon-coated iron ([email protected]) nanoparticles were firstly prepared. Then, using tetrabutyl titanate as the raw material, anhydrous ethanol as the solvent, and diethanolamine as the inhibitor, TiO2 sol doped with [email protected] nanoparticles was prepared. [email protected] doped TiO2 (TiO2[email protected]) thin films were prepared on the Fluorine Tin Oxide substrate at an annealing temperature of 500 °C, and the effects of different [email protected] contents on the surface structure and optical properties of the samples were investigated. The differences between undoped anatase TiO2 films and [email protected] doped TiO2 films were analyzed using various techniques, including X-ray diffraction, X-ray photoelectron spectroscopy, ultraviolet–visible spectroscopy, and field-emission scanning electron microscopy. The band gap width after doping was 2.48 eV, substantially lower than that of TiO2 films doped with a single metal Fe in literature (3.02 eV). This lower band gap width makes it an attractive option for use in the field of photoelectric conversion.