Mesoporous hollow TiO2 microspheres with enhanced photoluminescence prepared by a smart amino acid template

The simplest amino acid, glycine (C2H5NO2), was used as a multifunctional smart template to prepare mesoporous hollow TiO2 microspheres via a facile solvothermal method. In the fabrication process, glycine serves concurrently as a sacrificial template, complexing agent and water supplier. The hollow spheres were characterized as TiO2/organic hybrid structures and converted into well-defined mesoporous structures by calcination. The growth mechanism of the hollow spheres was demonstrated to include the self-conglobated smart template above the softening temperature, a consequent in situ hydrolysis on the template surface and then a sacrificial core evacuation process. From the demonstrated mechanism, the cavity volume can be easily controlled by the mass of crude glycine used. This novel method has successfully been applied in the synthesis of Eu-doped TiO2 hollow spheres. The Eu-doped sample exhibits stronger photoluminescence owing to the unique microstructures, compared to conventional hydrothermal samples.