Synthesis and antibacterial activity of transition metal (Ni/Mn) co-doped TiO$_2$ nanophotocatalyst on different pathogens under visible light irradiation

Visible light driven photocatalytically active mesoporous nanomaterials plays an indispensable role for antibacterial activity in low light applications. In this work, nanomaterials were handily prepared by varying the dopant concentrations from 0.25 to 1.0 Wt% using sol-gel method. All the prepared samples were characterized by Powdered X-ray diffraction (XRD), Scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), Ultraviolet-visible diffuse reflectance spectroscopy (UV/Vis-DRS), Transmission electron microscopy (TEM) and Brauner-Emmett-Teller (BET). The characterization results revealed that a photocatalytically active phase i.e.; anatase and rutile mixed phase was observed for co-doped catalyst samples. Due to substitutional doping of Mn and Ni by replacing Ti, the frequency shift of Ti–O–Ti in the catalyst samples was observed by FTIR. Further the catalyst shows roughmorphology, irregular particle shape with less particle size having high surface area, and reduced band gap energy. The photocatalytically active materials antibacterial activity was discerned by using Sphingomonas paucimobilis and Pseudomonas fluorescence. The result of antibacterial activity shows that among all nanocatalysts, NMT2 catalyst shows optimum zone of inhibition at 25.1 $\pm$ 0.2 mm for Sphingomonas paucimobilis and 18.1 $\pm$ 0.2 mm for Pseudomonas fluorescence compared to standard (chloramphenicol) value at 24.1 $\pm$ 0.1 mm and 23.1 $\pm$ 0.05 mm at 100 $\mu$g/mL respectively.