Dual-emission ratiometric fluorescence sensor based on in situ formation of MAPbBr3 perovskite nanocrystals in europium metal-organic frameworks for detection of methylamine gas

Organic-inorganic halide perovskite nanocrystals (PNCs) have been extensively utilized in the field of sensing, attributed to their superior optoelectronic properties, including high photoluminescence quantum yield, tunable band gap, and narrow full width at half maximum. However, the majority of sensors based on PNCs have traditionally relied on a single fluorescence signal emission and its intensity variations, leading to limitations in visualization resolutions. Hence, we developed a rapid, sensitive, and visually discernible dual-emission ratiometric fluorescence sensor for the detection of methylamine (MA) gas that based on the in situ formation of methylamine lead bromide (MAPbBr 3 ) PNCs within europium metal-organic frameworks (Eu-MOFs) in the ambient atmosphere. In this strategy, Eu-MOFs not only served as the protective matrices to enhance the stability of MAPbBr 3 PNCs but also as luminescent materials in ratiometric fluorescence sensing, owing to their exceptional luminescent properties. More importantly, benefiting from the excellent gas adsorption properties and protective abilities of MOFs, the proposed sensor demonstrates higher sensitivity, stability, and reproducibility. Experimental results indicated a good linear correlation with MA concentrations ranging from 9.0 to 90.0 ppm, achieving a limit of detection as low as 1.0 ppm. In comparison to other reported methodologies, this approach demonstrates a remarkably short response time of 20   seconds.