One-Step Synthesis of the Nitrogen and Sulfur Codoped Carbon Dots for Detection of Lead and Copper Ions in Aqueous Solution

Abstract

Herein, by using the green and cheap L-cysteine as the precursor, nitrogen and sulfur codoped carbon dots (NS-CDs) were synthesized via a facile one-step hydrothermal method. The obtained NS-CDs showed the relatively narrow size distributions (2.1~3.9 nm) with the lattice spacing of 0.29 nm, as well as the excitation-dependent photoluminescence (PL) emission activity with the quantum yield (QY) of 18%. More interestingly, the PL intensity of NS-CDs was quenched by the addition of copper or lead ions (Cu2+ or Pb2+), which was shown in the tradition detection method by PL spectra. The NS-CDs exhibited ultrasensitive colorimetric sensing capability for both Cu2+ and Pb2+ by the color variance using naked eyes without any further treating. Two different coupling ways for detecting Pb2+ and Cu2+ were induced by the analysis of the Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). And the as-prepared NS-CDs showed their potential application in the heavy metal ions detection for the wastewater determination.

Design of Fluorescent Carbon Dots (CDs) for the Selective detection of Metal‐Containing Ions

“…The quenching process was related to the static quenching mechanism for the detection of Cu 2+ ions, which denotes that a non‐fluorescent ground‐state complex is formed by the interaction between S/N‐CDs and the quencher, i. e., Cu 2+ ions. This was supported from the analysis of the FTIR and XPS spectra, from where was confirmed that the Cu−O and Cu−S bonds were coordination styles for the Cu 2+ ions in the S/N‐CDs [74] …”

“…This was supported from the analysis of the FTIR and XPS spectra, from where was confirmed that the CuÀ O and CuÀ S bonds were coordination styles for the Cu 2 + ions in the S/N-CDs. [74] In another recent investigation, Lan et al obtained CNPs, emitting in the range between 483 and 525 nm. The CNPs were obtained via a simple hydrothermal process using poly-3-thiopheneacetic acid (PTA) and NaOH.…”

Colorimetric and Fluorescent Sensing of Copper Ions in Water through o-Phenylenediamine-Derived Carbon Dots

“…The infrared spectrum of NSCDs is shown in Figure 2 b. Most of the observed peaks can be attributed to the different functional groups produced by the synthesis procedure; specifically, the peaks at 1112 cm −1 and 1401 cm −1 can be assigned to S = O bonds and C-S bonds, respectively, thus confirming the presence of sulfur [ 45 ]. In addition, the peak at 1523 cm −1 is due to C = N, while that at 752 cm −1 comes from N-H wagging [ 46 , 47 ].…”

Tuning the Sensing Properties of N and S Co-Doped Carbon Dots for Colorimetric Detection of Copper and Cobalt in Water

“…In the spectrum of pristine NS-CDs, some peaks are pointed out by arrows and attributed to the presence of different typical nitrogen functional groups produced by the hydrothermal synthesis of N-doped CDs [ 25 , 37 ]. Peaks at 1113 cm −1 and 1400 cm −1 may come from S=O bond and C-S bond, respectively, and indicate the presence of sulfur in NS-CDs [ 36 ]. Noticeable differences can be observed in the spectrum of NS-CDs + Cu(II) with all the peaks indicated by arrows strongly reduced due to interaction with Cu(II).…”

“…Within this framework, fluorescent sensing of Cu(II) ions has been the topic of many studies, both exploiting fluorescence quenching and turn-on effects [ 30 , 31 , 32 , 33 , 34 , 35 ]. Differently, absorption-based sensing of copper through CDs has rarely been reported [ 36 ] and deserves further investigations in view of applications to easy-to-use visual colorimetric devices.…”