Fluorescence sensing of ammonia in water using lead-free perovskite Cs2AgInCl6:Bi

Ammonia (NH3) is a common pollutant in water and an important indicator of environmental pollution. Its determination is of great significance to environmental protection. We synthesized ligand-free Cs2AgInCl6:Bi at room temperature to establish a low toxicity, rapid, and simple fluorescence assay for the selective determination of NH3 in water. Studies have shown that there is a good linear relationship with the concentration of NH3 in the range of 1.00 - 20.00 mg L-1 and the determination limit is 0.40 mg L-1. The selectivity for NH3 is higher than other substances may exist in the water (eg. Na+, SO42-). Subsequently, X-ray diffraction, scanning electron microscopy, fourier transform infrared spectroscopy, time-resolved fluorescence spectroscopy and ultraviolet absorption spectra were used to investigate the possible mechanism of NH3 reaction with Cs2AgInCl6:Bi. The water samples of lakes and rivers were analyzed by the proposed method and indophenolblue method, the results shown that there is no significant difference between the two methods. The reliable results (0.1%< RSD < 4.1%) and the satisfactory recovery (99.0%-102.5%) were obtained by direct determination method and mark recovery method. Therefore, the simple, rapid and low-toxicity fluorescence method established in this work provides a promising approach for NH3 analysis in environmental water.