Synthesis and characterization of TiO2 doped nanoparticles for application as antibacterial and antimicrobial coatings for frequent touch areas

Pristine TiO 2 , N-doped TiO 2 , Cu-modified TiO 2 prepared from chloride and sulphate precursors, and N-Cu co-modified TiO 2 were compared to determine how dopant type, precursor chemistry, and concentration influence physicochemical properties, methylene-blue decolorization, and antibacterial performance. The materials were characterized by SEM-EDS, XRD, XPS, FTIR, UV-DRS, and zeta-potential analysis and were evaluated as proof-of-concept paint coatings. SEM showed near-spherical primary particles of approximately 21 nm for pristine TiO 2 and 16 nm for N-TiO 2 , whereas the Cu-containing and co-modified materials were generally larger or more aggregated. XRD confirmed retention of predominantly anatase TiO 2 , while XPS identified N-containing states and precursor-dependent Cu surface chemistry: reduced and/or highly dispersed Cu species were favoured by the chloride route, whereas Cu 2 + /CuO-like species were evident for the sulphate route. The apparent optical bandgap decreased from 3.00 eV for pristine TiO 2 to 2.37 eV for N-TiO 2 and 2.45–2.57 eV for the Cu-containing materials. After 100 min of visible-light exposure, N-TiO 2 gave the highest endpoint methylene-blue decolorization (66.4%), compared with 55.9% for pristine TiO 2 . Against Staphylococcus aureus, N-TiO 2 and 6% Cu-TiO 2 produced descriptive reductions of 2.83 and 2.08 log10, respectively. These findings support further development of modified TiO 2 coatings, although charge-carrier dynamics, reactive oxygen species, coating durability, and nanoparticle leaching were not measured directly.