Oxygen vacancies induced room temperature ferromagnetism and gas sensing properties of Co-doped TiO 2 nanoparticles

In this work, we report the influence of oxygen vacancy related defects on the magnetism and gas sensing of TiO 2 nanoparticles doped with different concentrations of cobalt (1, 3 and 5 at.%) prepared by sol–gel method at room temperature. XRD and Raman studies confirmed the formation of anatase tetragonal TiO 2 nanoparticles and the studies also clearly supported that the Co atoms go into the Ti site in TiO 2 . The obtained nanoparticles of size 6–20 nm was identified by HRTEM. The distribution of particles and the elemental composition present in the sample were determined by SEM with EDS. UV–Vis absorption spectra showed that the incorporation of Co into the TiO 2 lattice leads to redshift in the optical response as well as lowering of band gap energy. The defect oriented emissions were seen from photoluminescence study. Functional groups of the samples were identified by FTIR. The magnetic result demonstrated that the prepared Co-doped TiO 2 nanoparticles exhibit room temperature ferromagnetism due to oxygen vacancy related defects on the surface of the sample. The ethanol sensing studies conducted at room temperature showed that Co-doped (5 at.%) TiO 2 with higher oxygen vacancies is more sensitive to ethanol compared with pure TiO 2 , and the results reveal that oxygen vacancies play a significant role in both magnetism and sensing properties.