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.