Prepraration And Photocatalytic Performance Of Different Morphologys TiO₂ Microspheres

Due to expanding applications such as in solar energy conversion, photocatalysis, water purification and lithium ion battery anode, TiO2 has attracted more and more attention. Nanostructured TiO2 with different shapes, sizes, and phases have been prepared by sorts of synthesis ways while which usually succeed with multi-step reactions or harsh conditions.In our work, various morphologies of TiO2 microspheres have been synthesized in one step by low temperature solvothermal method through modulating experimental conditions. The structures of the prepared TiO2 particles are either rutile or mixture of rutile and anatase. TiO2 particles mainly exhibit four shapes:nanowire, areatus microspheres, sea-urchins and flower-like microspheres.The crystal structures, morphologies and photocatalytic performances of the prepared TiO2 particles are characterized by XRD, SEM, DSC and TG, respectively. On this basis, TiO2 microspheres doped with Sn2+ or Zn2+ as ions modification are prepared. The structure, morphology and properties of the doped TiO2 microspheres are also characterized using XRD, SEM, TEM, XPS, BET, DSC and TG respectively. The photocatalytic performance is also tested. The main results and conclusions are listed as follows:1. Pure TiO2 microspheres are prepared in one step using low-temperature solvothermal method. The photocatalytic test shows that it reaches adsorption equilibrium in dark conditions for 0.5 h, and the total adsorption amount is 5%. Under ultraviolet light, the photocatalytic degradation reaches 40% after 1.5 h.2. TiO2 microspheres modified by different metal cations are prepared. When Sn2+ was chosen as modified ions, different sizes of sea urchin microspheres are successfully prepared by changing the composition of reactants and experimental conditions. The corresponding phase is either rutile or the mixture of rutile and anatase. In dark conditions after 0.5 h, the Sn2+ doped rutile TiO2 reaches adsorption equilibrium, and the total adsorption amount is 5%. Under ultraviolet light, the photocatalytic degradation reaches 95% after 1.5 h. The mixed phase of anatase/rutile displays the best catalytic performance.In dark condition after 0.5 h, it reached adsorption equilibrium, and the total adsorption amount is 8%. Under ultraviolet light, the photocatalytic degradation after 5 min reaches almost 98%. The best potocatalytic performance is mainly due to the formation of the mixed anatase/rutile structure and the largest specific surface.3. The Zn2+ modified TiO2 microspheres hold the most uniform shape, but the photocatalytic degradation reaches almost 90% after 60 min. which is no better than Sn2+ doped mixed anatase/rutile TiO2 structure.The results may provide indispensable experimental basis and theoretical foundation for the fabrication of TiO2 nanomaterials with superior properties.