Enhanced Mesostructural Order and Changes to Optical and Electrochemical Properties Induced by the Addition of Cerium(III) to Mesoporous Titania Thin Films

The addition of up to 10 mol % cerium(III) during the synthesis of cubic mesoporous titania thin films significantly increases the degree of mesostructural order in the final material. Photocurrent measurements, cyclic voltammetry, and spectroelectrochemistry show that the addition of cerium introduces a large number of interfacial states into the mesoporous material, which act as electron traps. Electron trapping by individual cerium ions also causes changes in the electrochemical properties of the mesoporous films. The mesoporous cerium-doped titania films show an increased electrochromic response that is indicated by an increase in absorbance at 550 nm with respect to pure titania. This effect is counter to the behavior of sol-gel ceria-titania films, which generally show a loss of electrochromism compared to pure titania.