Synthesis And Photocatalytic Activity Of Hierarchical BaTiO₃ Microspheres

Over the past few decades,nanomaterials and nanotechnology have been widely used in photocatalytic industries such as photocatalytic hydrogen evolution and photocatalytic degradation of organic pollutants.Among all the photocatalytic semiconductor,perovskite,especially BaTiO₃,has the advantages of environment friendliness,resources abundant,low-cost and chemical properties stable.However,low photocatalytic efficiency and poor repeatability are severe problems of this material,which have limitsed the possibility of large-scale industrial application.In this paper,the hierarchical nanostructures BaTiO₃ microspheres have been synthesized by the hydrothermal topochemical conversion and topochemical solid-state reaction.Furthermore,the synthesis mechanism and photocatalytic activity were discussed The hierarchical nanostructures H₂Ti₂O₅·H₂O microspheres constructed from nanosheets have been synthesized via a facile solvothermal method.The spherical micelles were formed via amphoteric surfactant of N,N-dimethylacetamide（DMAC）was added to isopropyl alcohol（IPA）solution,due to polar group of DMAc were attracted and nonpolar group of DMAc were repelled by the IPA solution.The hierarchical nanostructures H₂Ti₂O₅·H₂O microspheres constructed from nanosheets were prepared by the thermal decomposition of tetrabutyl titanate（TBT）under the influence of spherical micelles.The extent of polymerization,such as particle size,nanosheets size and pore volume,of the hierarchitectures microspheres can be adjusted by the concentration of DMAc and reaction temperature.When the solvent volume ratio of IPA/DMAc was 2.5/1 and the reaction temperature was 200℃,the specific surface area and pore volume reached a maximum of 102.6 m²·g^-1 and 0.45 cm³·g^-1.The hierarchical nanostructures BaTiO₃ microspheres have been synthesized via a the hydrothermal topochemical method using as-prepared H₂Ti₂O₅·H₂O precursor.The whole reaction process needs to experience a minimal reorganization of structure in the template,causing the formation of crystal structure with a higher symmetry than that of the precursor template,which is more stable.The photocatalytic performance of BaTiO₃hierarchical microspheres with good recycling performance was tested,its apparent rate is up to 0.10183 min^-1,almost 23 times higher than that for nanoscale BaTiO₃ particles,good recycling performance,due to the unique nanosheet assembled structure with mesopores embedded in nanosheets BaTiO₃ particles bring about high specific surface area and pore volume.In order to reduce production cost and improve production efficiency,the mesoporous BaTiO₃ microspheres were prepared by solid-state topochemical transformation using as-prepared H₂Ti₂O₅·H₂O microspheres.The photocatalytic efficiency is 9 times higher than that for nanoscale BaTiO₃ particles.