General strategy for ATiO3 (A = Ca, Sr, or Ba) submicrospheres with large surface area and its photocatalytic applications

Abstract

Porous CaTiO₃ solid submicrospheres and SrTiO₃ and BaTiO₃ hollow submicrospheres, which have large surface areas (40.21 to 228.18 m² g⁻¹) and uniform particle sizes, have been synthesized by a self-template assisted hydrothermal method with glucose as an additive. The results showed that the crystalline phase and morphology of ATiO₃ were significantly influenced by the addition of glucose. Samples with irregular morphology and weak crystallinity were obtained without glucose as the reactant. The underlying formation mechanism of SrTiO₃ and BaTiO₃ hollow submicrospheres in the presence of glucose was manifested by XRD, SEM and TEM to involve Sr²⁺, Ba²⁺, and OH⁻ ion diffusion, reactions and Ostwald ripening, while the formation of CaTiO₃ solid submicrospheres has a different growth mechanism during the hydrothermal process, that is, only diffusion–crystallization, without Ostwald ripening. The obtained porous SrTiO₃ hollow spheres show the highest photocatalytic performance on methylene blue, which may be related to the combined effects of surface area, band gap and interfacial charge transfer.