Highly photoluminescent and pH sensitive nitrogen doped carbon dots (NCDs) as a fluorescent sensor for the efficient detection of Cr (VI) ions in aqueous media

Jasjot Kaur; Shelja Sharma; Surinder Kumar Mehta; Sushil Kumar Kansal

doi:10.1016/j.saa.2019.117572

Highly photoluminescent and pH sensitive nitrogen doped carbon dots (NCDs) as a fluorescent sensor for the efficient detection of Cr (VI) ions in aqueous media

Spectrochim Acta A Mol Biomol Spectrosc. 2020 Feb 15:227:117572. doi: 10.1016/j.saa.2019.117572. Epub 2019 Oct 14.

Authors

Jasjot Kaur¹, Shelja Sharma², Surinder Kumar Mehta², Sushil Kumar Kansal³

Affiliations

¹ Dr. S.S. Bhatnagar University Institute of Chemical Engineering and Technology, Panjab University, Chandigarh, 160014, India.
² Department of Chemistry and Centre of Advanced Studies, Panjab University, Chandigarh, 160014, India.
³ Dr. S.S. Bhatnagar University Institute of Chemical Engineering and Technology, Panjab University, Chandigarh, 160014, India. Electronic address: sushilkk1@pu.ac.in.

PMID: 31670040
DOI: 10.1016/j.saa.2019.117572

Abstract

Fluorescent carbon dots (CDs) are contemporary class of fluorescent materials that has emerged recently and have gathered increasing attention due to its excellent properties as compared to traditional semiconductor quantum dots. CDs have lucrative benefits of less toxicity, biocompatibility, eco friendliness, tunable fluorescence, high chemical and photostability, effortless synthesis routes and uncomplicated surface modifications and functionalization. In the present work, nitrogen-doped carbon dots (NCDs) were prepared by a facile hydrothermal process using l-ascorbic acid and ethylene diamine as precursors. The as-prepared NCDs were hydrophilic in nature and could remain stable for several weeks. NCDs displayed bright blue fluorescence under UV light irradiation and also exhibited an extensive range of emission spectra in the visible region to infra-red region based upon the excitation wavelength. NCDs possessed quasi-spherical morphology and high density growth. NCDs were further utilized as nanoprobes for the pH sensing and proficient sensitive and selective detection of chromium (VI) ions present in aqueous phase. Under augmented modifications and conditions, the photoluminescence intensity of NCDs against various micromolar concentration of chromium (VI) ions presented a linear relationship, as per Stern-Volmer equation. The calibration curve was found to be linear in the range of 0-4 μM and from the slope of the linear curve, the limit of detection (LOD) was calculated to be 2.598 nM. The Stern-Volmer calibration curve was also plotted against different temperatures, verifying static quenching mechanism. Therefore, the as synthesized NCDs can be successfully demonstrated for the efficient pH sensing and the detection of Cr (VI) ions.

Keywords: Carbon dots; Fluorescence; Metal ions; Sensing.