Optical Properties of Titania–Zirconia Clusters: a TD-DFT Study

Time dependent density functional theory (TD-DFT) study of the optical properties of titania (TiO2), Zirconia (ZrO2) and their hybrid clusters TiZrO4 are reported. The UV–Visible spectra and Circular Dichroism spectra of the clusters were computed to investigate the molecular orbitals, excitation energies, electronic transitions, HOMO–LUMO characters, oscillatory and rotatory strengths of the clusters. The excitation energies of TiZrO4\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$TiZrO_{4}$$\end{document} starting from Zr2O4\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$Zr_{2} O_{4}$$\end{document} appeared in the visible and near UV region whereas the same is found in near UV region when starting geometry was switched to Ti2O4\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$Ti_{2} O_{4}$$\end{document}. The findings of this study revealed that the optical properties of the hybrid clusters are strongly influenced from the geometry of starting clusters. Further, the excitation spectra of the hybrid clusters possess the finger prints of the properties of the starting clusters. The optical activity of the hybrid clusters in visible and near UV regions points to potential of the materials for application in photocatalysis. The hybrid material points to possibility of preparation of tunable materials for use in electronic, optoelectronic, electrochemical/photo-catalytic applications and as chiral compounds.