Sequential Ionic Layer Adsorption and Reaction (SILAR) deposition of Bi4Ti3O12 on TiO2: an enhanced and stable photocatalytic system for water purification

A new method to produce bismuth titanate – titanium dioxide composites by modification of a TiO2 film deposited on a variety of different glass substrates is reported. Using a simple SILAR method, BiOBr may be deposited upon TiO2 surfaces, which upon heating forms a closely intercalated structure of bismuth titanate (Bi4Ti3O12, BTO) and TiO2. This new method expands the scope of the SILAR process, which is typically restricted to materials which can be formed from soluble precursors. This composite material has undergone a thorough materials characterisation to confirm the absence of the BiOBr precursor, and the formation of the new bismuth titanate phase. The electronic structure of the heterojunction formed has also been investigated by valence band XPS and diffuse reflectance measurements, and a plausible band structure proposed. The immobilised composites have then been applied to the photocatalytic degradation of organic pollutants and bactericidal testing, as well as stability tests and identification of the key reactive species. Further photocatalytic studies have been carried out on this material in a synthetic wastewater medium, taking a step towards application under real-world conditions.

本文报道了一种通过改性沉积于多种不同玻璃基底上的二氧化钛（TiO₂）薄膜来制备钛酸铋-二氧化钛复合材料的新方法。通过简单的连续离子层吸附反应（SILAR）法，可在TiO₂表面沉积溴氧化铋（BiOBr）；经加热后，该体系形成钛酸铋（Bi₄Ti₃O₁₂，BTO）与TiO₂紧密插层的结构。此新方法拓展了SILAR工艺的应用范围——该工艺通常仅限于由可溶性前驱体制备的材料。该复合材料已通过全面的材料表征，证实BiOBr前驱体已完全消失，且新的钛酸铋相已形成。通过价带X射线光电子能谱（XPS）与漫反射测量，研究人员还探究了所形成异质结的电子结构，并提出了合理的能带结构。随后，该固定化复合材料被应用于有机污染物的光催化降解、杀菌测试、稳定性测试以及关键活性物种的鉴定。此外，研究人员在模拟废水介质中对该材料开展了进一步的光催化研究，为其实际应用迈出了一步。