Monodisperse Spherical Sandwiched Structured SiO2@CsPbX3@SiO2 Perovskite Composites for the Determination of Fe3+ Ion in Water Samples

The application of all-inorganic CsPbX 3 (X = Cl − , Br − and I − ) perovskite nanocrystals (PNCs) is hindered by their poor stability under different environments (moisture, UV light and high temperature). Herein, we demonstrate a novel in-situ growth and post-coating technique to prepare monodisperse spherical sandwiched structured SiO 2 @CsPbX 3 @SiO 2 perovskite composites. In this strategy, the environmental stability of CsPbX 3 PNCs is remarkably improved due to protecting evenly distribution in the surface of composites through the design of spherical sandwiched structure, and the negative effects of SiO 2 coating on photoluminescence property of CsPbX 3 PNCs could be reduced effectively. Furthermore, regular monodisperse spherical structure and uniform size of composites greatly benefit their application in relative fields. The experiment results indicate that the as-prepared product have outstanding abilities of water-, oxidation- and UV radiation resistance. Finally, the SiO 2 @CsPbBr 3 @SiO 2 perovskite composites are successfully used for highly sensitive detection of Fe 3+ in water sample. The results show limit of detection (LOD) is 3 µM and good linearity is between 10 and 70 µM ( R 2  = 0.9963). Furthermore, the proposed perovskite composites have been successfully applied for the analysis of Fe 3+  in real samples with satisfactory results.