Effect of Fe3+ Doping in the Photocatalytic Properties of BaSnO3 Perovskite

In the last ten years, stannates with perovskite structure have been tested as photocatalysts. In spite of the ability of perovskite materials to accommodate different cations in its structure, evaluation of doped stannates is not a common task in the photocatalysis area. In this work, Fe3+ doped BaSnO3 was synthesized by the modified Pechini method, with calcination between 300 and 800ºC/4 h. The powder precursor was characterized by thermogravimetry after partial elimination of carbon. Characterization after the second calcination step was done by X-ray diffraction, Raman spectroscopy and UV-visible spectroscopy. Materials were tested in the photocatalytic discoloration of the Remazol Golden Yellow azo dye under UVC irradiation. Higher photocatalytic efficiency was observed under acid media. As no meaningful adsorption was observed at this condition we believe that an indirect mechanism prevails. Fe3+ doping decreased the band gap and favored the photocatalytic reaction, which may be assigned to the formation of intermediate levels inside the band gap.

近十年来，钙钛矿结构（perovskite structure）锡酸盐（stannates）已被作为光催化剂开展相关测试。尽管钙钛矿材料可在其晶格中容纳不同种类的阳离子，但针对掺杂型锡酸盐的性能评估在光催化领域仍较为少见。本研究通过改进的佩奇尼法（Pechini method）合成了三价铁离子（Fe³⁺）掺杂的锡酸钡（BaSnO₃），煅烧温度设定为300~800℃，保温4小时。在脱除部分碳后，通过热重分析法（thermogravimetry）对粉末前驱体进行了表征；第二次煅烧完成后，则采用X射线衍射（X-ray diffraction）、拉曼光谱法（Raman spectroscopy）以及紫外-可见分光光度法（UV-visible spectroscopy）对所得材料进行了表征。将所制备的材料应用于UVC辐照（UVC irradiation）下雷玛唑金黄偶氮染料（Remazol Golden Yellow azo dye）的光催化脱色实验。实验发现，酸性介质下材料表现出更高的光催化效率。由于在该条件下未观察到显著的吸附作用，我们推测反应主要遵循间接机理。三价铁离子掺杂可降低材料的能带隙（band gap），并促进光催化反应，这一现象可归因于能带隙内中间能级的形成。