Structural analysis and magnetic properties of cobalt-doped nanotitania

•Undoped and Co doped anatase TiO2 NPs are prepared by low cost sol-gel co-precipitation.•Redshift of the most intense Raman peak supports non-stoichiometry endorsing the creation of oxygen vacancies by Co doping.•Co doping causes significant diminution of band gap from 3.51 to 3.25 eV which is supported by DFT calculations.•Intrinsic weak ferromagnetism due to oxygen vacancies is dominated by paramagnetism giving rise to mixed magnetic phases.•Interacting BMPs culminate in the largest ferromagnetic contribution under the mixed magnetic phases.