Fluorescence Light‐Up Electrospun Membrane Incorporated with PbBr₂ as a Highly Selective Fluorescence Probe for the Detection of Cs+

Abstract This study introduces a novel fluorescent light‐up electrospun membrane, integrating PbBr 2 , which serves as an exceptionally selective probe for the detection of cesium ions (Cs + ). Leveraging the superior optical properties of CsPbBr 3 perovskite nanocrystals (PNCs), the researchers employ electrospinning technology to fabricate a test strip, namely PbBr 2 @polyacrylonitrile (PbBr 2 @PAN) nanofiber membranes, capable of swiftly detecting Cs + in water merely by observing changes in the nanocrystals' luminescence with the naked eye. By the introduction of NH 4 + ‐modified montmorillonite (NH 4 + ‐MMT), PbBr 2 ‐MT@PAN nanofiber membranes is obtained. The selectivity and sensitivity to Cs + can be further improved because NH 4 + ‐MMT endows PbBr 2 ‐MT@PAN nanofiber membranes with the hydrophilic property and selective adsorption toward Cs + ions. The membrane's fabrication is simple, scalable, and cost‐effective, with high cesium selectivity and sensitivity down to 44 ppb. This innovation enables efficient, on‐site cesium monitoring critical for environmental safety and nuclear waste management.