Traffic light-type ratiometric fluorescence visual sensing of Cs in soybean oil based on dimension regulation of 2D perovskite nanosheets.

Determination of cesium ion in soybean oil is of high importance since the increasing risk from releasing of main component of nuclear waste cesium 137. The complex composition and high viscosity of soybean oil make it necessary to convert it into water phase by nitration before detection, so developing a simple, accurate and sensitive method for on-site sensing of Cs in soybean oil is still a big challenge. In this work, we report a traffic light-type ratiometric fluorescence strategy for the visual sensing of Cs in soybean oil based on dimensional regulation of two dimensional (PEA)PbI perovskite nanosheets (NSs). The PEA in (PEA)PbI NSs exchanged with Cs and lead to dimension of partial (PEA)PbI NSs progressively increase from 2D to 3D CsPbI NCs. Resultantly, the fluorescence of (PEA)PbI NSs decreases with a concomitant fluorescence enhancement of CsPbI NCs upon increasing the concentrations of Cs, and the emission accordingly change from green, yellow to red with a high fluorescence colorimetric resolution up to 5.0 μM, make it successful to achieve on-site sensing of Cs in soybean oil just with naked eye in 5 min without any nitration, demonstrating a bright application future for determination of Cs in the soybean oil.