Nitrogen and sulfur co-doped carbon quantum dots as "on-off-on" fluorescence probes to detect Hg and MnO and improving the photostability of Rhodamine B.

Background: Carbon quantum dot (CQDs) are zero-dimensional carbon nanomaterials with a size of less than 10 nm CQDs are widely used in the field of ion detection by virtue of their fluorescence characteristics such as strong fluorescence intensity, good optical stability and tunable emission wavelength. Although the traditional atomic absorption method, electrochemical method and other metal ion detection methods are highly sensitive, the operation is complex, expensive and limited by the site. Therefore, we prepared the N, S-CQDs capable of detecting Hg and MnO in water with the advantages of simple operation, low cost, and direct visual signal.

Novel highly selective fluorescence sensing strategy for Mercury(Ⅱ) in water based on nitrogen-doped carbon quantum dots.

In this work, a fluorescent signal-closing probe of nitrogen-doped carbon quantum dots (NCQDs) was developed for quantitative detection of mercury ions (Hg). In this detection system, the NCQDs with high quantum yield (QY, 63.80 %) were synthesized via simple hydrothermal method with Methyl Glycine Diacetic acid Trisodium Salt (MGDA) and m-phenylenediamine (MPD) as carbon and nitrogen sources.

Preparation of nitrogen-doped carbon quantum dots from chelating agent and used as fluorescent probes for accurate detection of ClO and Cr(Ⅵ).

In this study, a novel ionic sensor based on nitrogen-doped carbon quantum dots (N-CQDs) was developed for sensitive detection of hypochlorite ions (ClO) and dichromate ions (Cr(Ⅵ)) by fluorescence spectrometry. The N-CQDs was synthesized by hydrothermal method using Methyl Glycine Diacetic acid Trisodium Salt (MGDA) and Ethylenediamine (EDA) with bright blue fluorescence, high fluorescence quantum yield, abundant surface groups and good dispersion. The N-CQDs had a remarkable emission characteristic at 450 nm under the ultraviolet light of 350 nm, and the ClO and Cr(Ⅵ) ions could quantificationally quench the fluorescence of this emission band.