Synthesis of a water-stable CsPbBr 3 perovskite for selective detection of mercury ion in water.

By using the method of low-temperature crystallization, CsPbBr 3 perovskite nanocrystals (PNCs) coated with trifluoroacetyl lysine (Tfa-Lys) and oleamine (Olam) were synthesized in aqueous solution. The structure of the CsPbBr 3 PNCs was characterized by many methods, such as ultraviolet (UV)-visible absorption spectrophotometer, fluorescence spectrophotometer, transmission electron microscopy (TEM), and X-ray diffraction (XRD) pattern. The fluorescence emission of the CsPbBr 3 PNCs is stable in water for about 1 day at room temperature. It was also found that the fluorescence of the PNCs could be obviously and selectively quenched after the addition of mercury ion (Hg 2+ ), allowing a visual detection of Hg 2+ by the naked eye under UV light illumination. The fluorescence quenching rate (I 0 /I) has a good linear relationship with the addition of Hg 2+ in the concentration range 0.075 to 1.5 mg/L, with a correlation coefficient (R 2 ) of 0.997, and limit of detection of 0.046 mg/L. The fluorescence quenching mechanism of the PNCs was determined by the fluorescence lifetime and X-ray photoelectron spectroscopy (XPS) of the PNCs. Overall, the synthesis method for CsPbBr 3 PNCs is simple and rapid, and the as-prepared PNCs are stable in water that could be conveniently used for selective detection of Hg 2+ in the water environment.