Structural, optical, photocatalytic, and antimicrobial activities of cobalt-doped tin oxide nanoparticles

In this study, pure and Co-doped tin oxide (SnO 2 ) nanoparticles were synthesized by sol–gel method, and the effect of Co-doping on the structural, optical, photocatalytic, and antimicrobial activities was studied. The prepared samples were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, UV–visible diffuse reflectance spectroscopy, and N 2 adsorption/desorption analysis. The XRD patterns of all the samples are identified as tetragonal rutile-type SnO 2 phase which is further confirmed by TEM analysis. The optical spectra showed redshift in the absorption edge of doped samples, which enhances their absorption toward the visible light region. The photocatalytic activity of all the samples was assessed by monitoring the degradation of methylene blue solution under daylight illumination, and it was found that the photocatalytic activity significantly increases with the increase in dopant concentration, which is due to the effective charge separation of photogenerated electron–hole pairs. The antimicrobial studies investigated against standard bacterial and fungal strains showed enhanced antimicrobial activity in doped samples, which can be attributed to the production of reactive oxygen species and large surface area of the nanoparticles. Graphical abstract