We have reported the synthesis of strontium titanate (ST) nanomaterials via sol-gel combustion method in the presence and absence of pluronic P123 as a templating agent and citric acid as fuel at relatively high temperature. The presence of templating agent and fuel helps to generate mesoporosity in the materials resulting in mesoporous strontium titanate (MST). The materials are well characterized by various instrumental techniques. X-ray powder diffraction analysis has confirmed that both of the strontium titanate materials exhibited cubic perovskite structure. The FT-IR spectra has indicated that during high temperature calcination, carbonate species expelled out from the decomposition of the volatile impurities get adsorbed on the surface of titanate nanostructure, which is predominant in MST as indicated by the variation in the intensity of peak in between 1450 cm-1 –1470 cm-1. From diffuse reflectance spectra, the absorption edge of the MST is extended to visible regions and showed band gap energy of 3.14 eV compared to 3.21 eV for ST. The reduction in intensities of PL emission bands in MST compared to ST has indicated that slow electron-hole recombination takes place in this material compared to ST. The Transmission electron microscopic studies reveal the formation of spherical and cuboidal nanostructures with an average size of 55 and 38 nm for ST and MST material, respectively. From N2 sorption studies, the MST exhibit type IV adsorption isotherms with H3 type hysteresis loop indicated the formation of mesoporosity in this material whereas the ST indicated the formation of type II adsorption isotherms typical of nonporous materials. The elemental analysis of MST material is further confirmed from X-ray photoelectron spectroscopic analysis and confirm the formation of carbonate species on the surface of the materials. The photocatalytic activity of the materials is elucidated by the degradation of methylene blue under UV light irradiation and degradation followed first order kinetics with Langmuir-Hinshelwood adsorption pathways. The activity of MST material is found to be 5 times faster than ST at similar experimental conditions. The enhanced activity of the MST might be attributed to, lower band gap energy, presence of carbonate species, and lower electron-hole recombination in this material.

中文翻译：

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P123辅助溶胶-凝胶燃烧合成介孔钛酸锶纳米材料光催化降解亚甲基蓝

我们已经报道了在存在和不存在 pluronic P123 作为模板剂和柠檬酸作为燃料的情况下，在相对较高的温度下，通过溶胶-凝胶燃烧法合成钛酸锶 (ST) 纳米材料。模板剂和燃料的存在有助于在材料中产生介孔，从而产生介孔钛酸锶 (MST)。这些材料通过各种仪器技术得到了很好的表征。X 射线粉末衍射分析已证实两种钛酸锶材料均表现出立方钙钛矿结构。FT-IR光谱表明，在高温煅烧过程中，挥发性杂质分解排出的碳酸盐物质吸附在钛酸盐纳米结构的表面，这在 MST 中占主导地位，如 1450 cm-1 –1470 cm-1 之间峰强度的变化所示。从漫反射光谱来看，MST 的吸收边缘扩展到可见光区域，并显示出 3.14 eV 的带隙能量，而 ST 的带隙能量为 3.21 eV。与 ST 相比，MST 中 PL 发射带强度的降低表明，与 ST 相比，这种材料中发生了缓慢的电子-空穴复合。透射电子显微镜研究表明，ST 和 MST 材料分别形成了平均尺寸为 55 和 38 nm 的球形和立方体纳米结构。从 N2 吸附研究中，MST 表现出 IV 型吸附等温线，H3 型滞后回线表明在该材料中形成了介孔，而 ST 表明形成了典型的无孔材料的 II 型吸附等温线。MST材料的元素分析通过X射线光电子能谱分析得到进一步证实，并证实了材料表面碳酸盐物种的形成。材料的光催化活性通过在紫外光照射下降解亚甲基蓝来阐明，降解遵循 Langmuir-Hinshelwood 吸附途径的一级动力学。在类似的实验条件下，发现 MST 材料的活性比 ST 快 5 倍。MST 的活性增强可能归因于较低的带隙能量、碳酸盐物质的存在、