Luminescence characteristics of cobalt doped TiO2 nanoparticles

► Cobalt doping results in the increase in d-spacing and shifting of XRD peak position. ► Decrease in photoluminescence intensity of TiO2 after doping indicates inhibition of electron-hole recombination. ► Concentration quenching effect results in decrease in visible emission intensity ratio. ► Excitation peaks related to oxygen defects and Co2+ are observed in photoluminescence excitation spectra. ► Cobalt doped TiO2 has longer decay time compared to undoped TiO2.