A solid-state colorimetric fluorescence Pb²⁺-sensing scheme: Mechanically-driven CsPbBr₃ nanocrystallization in glass

Highly toxic Pb²⁺ poses a great threat to the health of human beings and ecosystems, urgently calling for an efficient Pb²⁺ detection method. Herein, we demonstrated a brand-new solid-state fluorescence Pb²⁺-sensing scheme based on a type of Pb²⁺-responsive borate glass powder that is able to precipitate CsPbBr₃ nanocrystals on the glass surface upon grinding with Pb²⁺ sources, following a mechanically driven glass crystallization mechanism. Pb²⁺ sensing is achieved via the Pb²⁺ concentration-dependent green emission of CsPbBr₃ as an indicator signal and independent red emission of Eu³⁺ as a reference signal. Under UV light irradiation, the obvious emissive color variation from red to green as Pb²⁺ concentration varies enables the intuitive Pb²⁺-sensing by naked eyes. With the aid of a spectrometer and smartphone, Pb²⁺ concentration can be quantitatively determined with the detection limit as low as ∼70 ppm and ∼400 ppm, respectively. The semi-quantitative Pb²⁺ detection is also possible by comparing the emissive color with the calibrated color card. Hopefully, the proposed solid-state fluorescence Pb²⁺-sensing strategy with high selectivity can be used for portable and quick Pb²⁺ analysis in daily life.