Towards recyclable optical nitrite sensing composite structures: Design, synthesis, characterization and sensing performance.

Two site-specific nanocomposite samples were designed and prepared for nitrite sensing. A core-shell structure was applied in them, using FeO nanoparticles as core, silica molecular sieve MCM-41 as shell and two rhodamine derivatives as chemosensor, respectively. These two composite samples and their core-shell structure were investigated by electron microscopy images, N adsorption/desorption, magnetic property, IR spectra and thermogravimetric analysis. Nitrite sensing performance of these two composite samples was evaluated with their emission quenching. Limit of detection was determined as 1.1μM. Further analysis indicated that our chemosensors followed a static sensing mechanism based on an additive reaction between NO and chemosensors. These two composite samples showed recyclability after being quenched by nitrite.