Preparation of C and Co co-doped TiO2 Nanomaterials for Visible-Light Photocatalytic Antibacterial Activity

Titanium dioxide (TiO 2 )-mediated photodynamic therapy has emerged as a promising antibacterial strategy. To further enhance the photocatalytic activity of TiO 2 , we have rationally designed cobalt-doped TiO 2 nanocomposites (C/Co/TiO 2-x ) via a sol–gel synthesis approach. The synthesized materials were systematically characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS). Structural analyses confirmed the presence of Ti, O, C, and Co elements, exhibiting a block-like morphology with a dominant anatase crystalline phase. Notably, the optimized material exhibits an extended visible-light absorption edge (762 nm) accompanied by a reduced band gap (1.63 eV), demonstrating significantly enhanced visible-light harvesting efficiency. Antibacterial evaluations revealed that the C/Co/TiO 2-x nanocomposite (5 mg/mL) achieved complete inactivation of Staphylococcus aureus ( S. aureus ) and Escherichia coli ( E. coli ) within 60 and 100 min, respectively, under visible-light irradiation (7 W LED). Radical trapping experiments identified photogenerated holes (h + ) and hydroxyl radicals (·OH) as the predominant reactive species responsible for bacterial inactivation. In vitro cytotoxicity assessment demonstrated excellent biocompatibility of the material. This study successfully illustrates the synthesis of C/Co/TiO 2-x nanocomposites, which exhibit promising potential for antibacterial applications.