The structural, optical, and antibacterial properties of Cd/Co co-doped TiO2.

[Display omitted] • Cd/Co co-doped TiO 2 nanoparticles are successfully synthesized. • Structural, morphological, and optical characteristics are investigated. • The optical bandgap reduced for an optimum Co concentration. • Cd/Co co-doped TiO 2 revealed substantial antibacterial properties. Emergence of multidrug-resistant bacterial strains due to the frequent use of antibiotics has led scientists to develop new materials to protect human health. Metal oxides such as titania (TiO 2) can play an effective role in controlling the infections caused by multidrug-resistant bacterial strains, however, its wide bandgap has limited its utilisation. In this study, we have doped TiO 2 with cadmium (Cd) and cobalt (Co) to tune its bandgap for enhanced antibacterial characteristics. Hydrothermal route was used to prepare a series of TiO 2 , Cd-doped and Cd/Co co-doped TiO 2 nanoparticles (NPs), with varying content of Co. Structural studies of the prepared samples revealed the formation of crystalline tetragonal anatase phase of TiO 2 with average crystallite sizes between 5 and 10 nm. The XRD results were further supported by the Raman analysis, where vibrational modes associated the anatase TiO 2 were observed. The Raman data indicated a gradual shift and broadening of peaks with the increase in Co concentration. Field-emission scanning electron microscopy (FE-SEM) images revealed the aggregated surface morphology for all the prepared samples. UV excitonic and visible emission peaks due to the defect centres associated with oxygen vacancies were observed in photoluminescence (PL) spectra. A substantial decrease in the bandgap of TiO 2 from 3.02 eV to 2.47 eV was achieved by doping TiO 2 with only 1 % Cd and 1 % Co. Compared to pure TiO 2 samples, Cd/Co co-doped TiO 2 NPs displayed superior antibacterial activity against the notorious P. aeruginosa and B. subtilis strains. [ABSTRACT FROM AUTHOR]