Carbon dots-MnO2 based turn-on fluorescent probe for rapid and sensitive detection of hydrazine in water

Abstract

Herein, a novel carbon dots-MnO2 assembly based fluorescent probe has been developed for sensitive and rapid detection of hydrazine in aqueous media. The Forster resonance energy transfer (FRET) based sensing platform was devised by adhering fluorescent carbon dots (CDs) on to MnO2 nanosheets in which MnO2 nanosheets act as a quencher and the inherent fluorescence of CDs gets quenched upon interaction with it by electrostatic interaction. This sensing platform selectively responds to hydrazine in the presence of environmentally relevant amines, metal ions, anions and other competing reducing species such as glutathione (GSH). Strong reducing ability of hydrazine effects quick conversion of Mn4+ in the nanosheets to free Mn2+ ions, which is immediately scavenged by glycine. As MnO2 nanosheets break apart the CDs loose free and go to a disperse phase in aqueous solution to emit greenish-blue fluorescence. A sharp rise in fluorescence intensity at 445 nm was observed upon gradual addition of hydrazine with a linearity range from 0.15 to 1.5 μM and a detection limit of 4.8 ppb for hydrazine was estimated which is below the US-EPA set threshold limit of 10 ppb. This cost-effective sensing tool with complete avoidance of toxic organic solvents for synthesis and fluorimetric studies coupled with high selectivity and sensitivity, rapid detection, low detection limit is a much viable alternative to existing detection tools for on-site detection and quantitation of hydrazine.