Hydrothermal synthesis and characterization of carbon-doped TiO₂ nanoparticles

We report the hydrothermal growth of pure and doped TiO₂ nanoparticles with different concentrations of carbon. The microstructure of the as-synthesized samples is characterized by x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive x-ray spectroscopy (EDX), and Raman spectroscopy to understand the structure and composition. The XRD patterns confirm the formation of anatase phase of TiO₂ with the average crystallite size is calculated to be in the range of 13 nm to 14.7 nm. The functional groups of these nanostructures are characterized by Fourier transformed infrared (FT-IR) spectroscopy, which further confirms the single anatase phase of the synthesized nanostructures. UV-visible absorption spectroscopy is used to understand the absorption behavior, which shows modification in the optical bandgap from 3.13 eV (pure TiO₂) to 3.74 eV (1.2 mol% C-doped TiO₂). Furthermore, the Ti³⁺ centers associated with oxygen vacancies are identified using electron paramagnetic resonance spectroscopy (EPR).