CsPbBr3@TiO2核壳结构纳米复合材料用作水稳高效可见光催化剂

CsPbBr₃钙钛矿量子点在水中的不稳定性一直是限制其应用的关键因素。本工作采用钛酸四丁酯水解结合煅烧的方法在CsPbBr₃表面包覆TiO₂保护层, 制备了一种具有良好水稳定性和光催化活性的CsPbBr₃@TiO₂核壳结构纳米复合材料。所合成的CsPbBr₃钙钛矿量子点尺寸约为8 nm, 包覆层为不完全结晶的TiO₂, 其厚度约为20 nm。采用在可见光下降解水中有机污染物罗丹明B表征了CsPbBr₃@TiO₂复合材料的光催化性能。结果表明, CsPbBr₃@TiO₂复合材料的光催化性能远优于纯TiO₂和CsPbBr₃钙钛矿量子点。光电流测试结果表明, CsPbBr₃和TiO₂形成的异质结构能够促进光生载流子的分离, 从而提升CsPbBr₃@TiO₂复合材料光催化性能。更重要的是, TiO₂可以作为CsPbBr₃的保护层将CsPbBr₃和水分隔开来, 使得CsPbBr₃@TiO₂复合材料具有很好的水稳定性。经过光催化降解污染物之后, 回收的CsPbBr₃@TiO₂复合材料的形貌、发光和光催化性能保持不变。

CsPbBr3@TiO2 Core-shell Structure Nanocomposite as Water Stable and Efficient Visible-light-driven Photocatalyst

The inherent poor stability of CsPbBr₃ perovskite quantum dots (QDs) is the main impediment restricting their applications. In this work, a CsPbBr₃@TiO₂ core-shell structure nanocomposite with high water stability and efficient photocatalytic activity was fabricated through the hydrolysis of tetrabutyl titanate, followed by calcination. The as-prepared CsPbBr₃ QDs have a size of ca. 8 nm, encapsulated by incompletely crystallized TiO₂ protective layer with a thickness of ca. 20 nm. The photocatalytic performance of the CsPbBr₃@TiO₂ nanocomposite was investigated by degradation of Rhodamine B (RhB) in water under visible light irradiation. The result shows that the CsPbBr₃@TiO₂ nanocomposite exhibits much more enhanced photocatalytic activity than pure TiO₂ and CsPbBr₃ perovskite quantum dots. The photocurrent test results showed that the formation of the CsPbBr₃@TiO₂ heterostructure can promote the separation of photogenerated carriers, which led to the improvement of photocatalytic performance of the composite material. More importantly, TiO₂ can act as a protective layer to separate CsPbBr₃ from water, which brings about the high water stability of the CsPbBr₃@TiO₂ nanocomposite. After photocatalytic degradation of pollutants, the recovered CsPbBr₃@TiO₂ nanocomposite retained its original morphology, luminescent and photocatalytic properties.