Structural, Magnetic, and Catalytic Properties of Mn-Doped Titania Nanoparticles Synthesized by a Sol–Gel Process

TiO2 nanoparticles (NPs) doped with different concentrations of manganese (1–8 at.%) were synthesized by sol–gel method and characterized to determine their structure, optical, and magnetic properties. X-ray diffraction analysis confirmed the formation of Mn-doped TiO2 NPs with anatase structure and that no impurity phases were present. X-ray photoelectron spectroscopic data indicated that the amount of Mn in the doped TiO2 samples was slightly lower than the theoretical value, and scanning electron microscope images illustrated a morphology consisting of un-aggregated, well-arranged NPs with a homogeneous size distribution. Particle sizes determined from transmission electron microscope images were found to be 17 and 11 nm for pure and Mn-doped TiO2, respectively. The band gap for pure TiO2 was calculated to be 3.26 eV from ultraviolet–visible reflectance spectra, which decreased to 2.70 eV following 8% Mn-doping. The as-prepared pure TiO2 NPs were found to be weakly paramagnetic at room temperature from vibrating sample magnetometer; however, a transformation from paramagnetic to weak ferromagnetism at room temperature was observed for Mn-doped TiO2 (5 at.%) NPs. Mn doped TiO2 (5 at.%) NPs exhibited the higher antibacterial activity against Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa than the pure TiO2 NPs.