Correlations between Theoretical and Experimental Results in C-doped TiO2 Nanostructured Materials

MATOS, J.; CAMPOS, K.; MONTAÑA, R., TITIRICI, M.M.:
Proceedings, Carbon for Energy Storage and Environment Protection – CESEP’2017, October 2017, Page 126.

Abstract

Theoretical estimations of the density of states by DFT + U approach were performed. Electron charges and energy band gap of pristine anatase TiO₂ and C-doped TiO₂ were estimated and a decrease from 3.14 to 2.94 eV in a Ti₁₅O₃₂C super-cell in comparison than pristine anatase TiO₂ was found. Results showed that doping of crystalline framework in anatase TiO₂ clearly changes the density of states around oxygen as of function of carbon doping. Correlations of theoretical estimations with the experimental photocatalytic activity [1] in the methylene blue and phenol photo oxidation under solar irradiation were found and associated with a decrease in the energy band gap in the semiconductor explaining the red-shift detected in the UV-Visible diffuse reflectance (UV-Vis/DR) absorption spectra and the increase in the photocatalytic activity of hybrid C-doped nanostructured TiO₂-based materials in the photodegradation of phenol and methylene blue. The visible light response of C- doped TiO₂ has been also associated with the presence of 2p orbitals of C atom. Theoretical estimations also confirmed that C-doped TiO₂ became as quantum-dots materials and therefore, the control of structural defects in the TiO₂ framework can be used as a valuable tool for the synthesis of electrodes for the quantum-dots sensitized solar cells.