CTAB-assisted fabrication of Zn-doped TiO 2 with improved dielectric performance and electrical response for energy storage and photocatalytic activity

The synthesis of undoped and Zn-doped TiO 2 prepared by the Stöber modified sol-gel technique and characterized for their microstructural, compositional, optical and electrical properties. XRD patterns have shown the existence of a single anatase crystalline phase. Grain sizes calculated by the Rietveld method were obtained with a decrease of 28 to 12 nm do to the incorporation of both CTAB and Zn content doping. An optical study shows a red shift with a band gap narrowing (from 3.2 to 3.1 eV) attributed to the formation of defects in the host lattice. The Raman spectra showed both broadening and shifting of the TiO 2 bands with decreasing particle size. The electric and dielectric spectra have been successfully studied in the frequency range of 40 Hz to 1 MHz between 500 K to 600 K. With the rising temperature, the dc conductivity values remain close to 10 − 8 S/cm, and the activation energies rise from 0.37 to 1.2 eV, respectively. The ac conductivity follows the Jonscher power law, which depends obviously on the Zn amount. Nyquist plots were fitted to a parallel combination of a resistance and constant phase (CPE) circuit. These results strongly suggest that the oxygen vacancies play a pivotal role and these oxides are potential candidate for photocatalysis device applications.