Bright yellow fluorescent carbon dots as selective nanoprobe for detection of 2-nitrophenol and 4-nitrophenol in aqueous medium

Different types of phenolic pollutants pose a major risk to the environment and the health of living things. It is therefore crucial for their selective recognition especially nitrophenols. In this work, yellow fluorescent carbon dots (C-dots) were used as selective nanoprobe to efficiently detect 2-nitrophenol (2-NP) and 4-nitrophenol (4- NP). One-pot synthetic method was adopted for making C-dots from o-phenylenediamine and oleic acid mixture. The synthesized C-dots showed an excitation wavelength of 420 nm with Stokes shift of up to 135 nm. These Cdots exhibited instantaneous selective detection of 2-NP and 4-NP in aqueous solution with a detection limit of 6.4 nM and 4.8 nM respectively. Upon incubated with 2-NP and 4-NP, the C-dots' fluorescence underwent quenching with a maximum extent of respective 80 % and 83 %. By comparing with other analogs of analyte, it was discovered that the emission intensity of the C-dots remained unchanged. Static quenching was proposed behind the changes of fluorescence after the treatment with 2-NP and 4-NP. Such type of C-dots will demonstrate the selective sensing platform in real field application.