A Novel Templated Method Of Hollow SiO₂/TiO₂ Nanospheres Preparation And Characterization

Recently, synthesis of inorganic hollow particles ranging from nanometer to micrometer scale is attracting increased interests, since their potential applications and remarkable properties in photosensor, storage, catalysis, and sensing detective. A novel and single template method to prepare hollow SiO₂ /TiO₂ spheres is proposed in this paper. We explore and study the influences of different operation conditions on the reaction, such as templates, ammonia ?NH4OH? and tetraethyl orthosilicate ?TEOS?; furthermore, we make an assumption and demonstration for the coating process, as follows.1. Preparing PAANa template through anionic PAANa aggregating in ethanol by nanoprecipitation, the hydrolysis and condensation of TEOS on the templates through sol-gel process under the catalysis of NH4OH, and removal of the water-soluble templates by washing with water. Hollow silica particles with controllable diameters ?100?200nm?, thicknesses ?15?40nm? and morphologies can be obtained ultimately under the control of PAANa solution, Tetraethyl orthosilicate ?TEOS? and NH4H. We also prove that the hollow SiO₂ spheres can be well used for Pb2+ and Cr3+ absorbent in wastewater.2. Making the assumption and demonstration for the coating process:the anionic templates prepared by nanoprecipitation were water-rich structures, these superabsorbent templates act as a nanoreactor are capable of adsorption or forming with TEOS; furthermore, the hydrogen-bond interaction between carboxyl and silicon hydroxyl groups maybe also useful. Similarly, we can prepare hollow TiO₂ spheres with PSSNa or PAANa/PSSNa templates.3. The P?St-co-AA? of carboxylation was prepared based on the styrene?St? and acrylic acid ?AA? participated soap-free emulsion polymerization, these anionic templates can be used to get raspberry-like composite particles with different operation factors, dichloromethane ?CH₂Cl₂? was added to fabricate hollow structures; when we reduce the AA amount in polymerization, the new obtained P?St-co-AA? particles were not successfully to be coated by silica.