Investigation of structural, optical, electrical, magnetic and antibacterial properties of (Mn and Sm) co-doped CdO nanostructures

This investigation studies the effect of Mn and Sm co-dopants on the properties of CdO nanostructures. With the aid of co-precipitation technique, Cd1–2xMnxSmxO (x = 0.00, 0.005, 0.01, 0.02, 0.03, and 0.04) nanostructures, denoted by CdO, co-0.5, co-1, co-2, co-3 and co-4, respectively were synthesized. The crystallinity and phase formation of the prepared samples were confirmed by X-ray powder diffraction. The doped samples exhibited larger lattice parameters and strain as compared to the pure sample. Transmission electron micrographs revealed the formation of nanowires for pure and low co-doped concentrations and nanowires with nanoclusters for higher co-doped concentrations. The Raman spectra disclosed the major phonon modes of CdO without any indicator from the co-dopants, proving that they were well integrated into the CdO lattice. The UV–Vis spectra revealed the tunable energy gap with the co-dopants’ concentration. The photoluminescence spectroscopy indicated the abundance of Cd interstitials and O/Cd vacancies. The DC conductivity indicated the metallic behavior of the prepared samples, triggered by Cd2+ vacancies, and the semiconducting behavior at high temperatures for co-1 and co-2. CdO and co-0.5 showed a weak ferromagnetic behavior combined with diamagnetic behavior; however, superparamagnetic along with an antiferromagnetic behavior was detected for higher doping concentrations. The origin of ferromagnetism may be related to O/Cd vacancies. Remarkably, all the samples prevented the growth of bacteria and formed well-defined zones around the samples with a stronger antibacterial activity on gram-negative (Escherichia coli, Citrobacter Braakii, and Klebsiella pneumoniae) than that on gram-positive bacteria (Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus intermedius).