“…with long pair electrons in the N-CDs, which can cooperate with Hg 2+ ions to generate complexes, resulting in electron transfer from the N-CDs to Hg 2+ ( Figure 9 d). Moreover, according to the previous reports, the introduction of N doped into the graphitic structure of N-CDs could regulate the electron density of N-CDs and promote coordination between oxygen-containing functional groups on the surface of N-CDs and Hg 2+ [ 26 , 64 ]. Therefore, when Hg 2+ is present, fast electron transfer can shift from the LUMO levels of N-CDs to Hg 2+ , leading to N-CD fluorescence quenching.…”
We developed a microreactor with porous copper fibers for synthesizing nitrogen-doped carbon dots (N-CDs) with a high stability and photoluminescence (PL) quantum yield (QY). By optimizing synthesis conditions, including the reaction temperature, flow rate, ethylenediamine dosage, and porosity of copper fibers, the N-CDs with a high PL QY of 73% were achieved. The PL QY of N-CDs was two times higher with copper fibers than without. The interrelations between the copper fibers with different porosities and the N-CDs were investigated using X-ray photoelectron spectroscopy (XPS) and Fourier Transform infrared spectroscopy (FTIR). The results demonstrate that the elemental contents and surface functional groups of N-CDs are significantly influenced by the porosity of copper fibers. The N-CDs can be used to effectively and selectively detect Hg2+ ions with a good linear response in the 0~50 μM Hg2+ ions concentration range, and the lowest limit of detection (LOD) is 2.54 nM, suggesting that the N-CDs have great potential for applications in the fields of environmental and hazard detection. Further studies reveal that the different d orbital energy levels of Hg2+ compared to those of other metal ions can affect the efficiency of electron transfer and thereby result in their different response in fluorescence quenching towards N-CDs.
“…with long pair electrons in the N-CDs, which can cooperate with Hg 2+ ions to generate complexes, resulting in electron transfer from the N-CDs to Hg 2+ ( Figure 9 d). Moreover, according to the previous reports, the introduction of N doped into the graphitic structure of N-CDs could regulate the electron density of N-CDs and promote coordination between oxygen-containing functional groups on the surface of N-CDs and Hg 2+ [ 26 , 64 ]. Therefore, when Hg 2+ is present, fast electron transfer can shift from the LUMO levels of N-CDs to Hg 2+ , leading to N-CD fluorescence quenching.…”
We developed a microreactor with porous copper fibers for synthesizing nitrogen-doped carbon dots (N-CDs) with a high stability and photoluminescence (PL) quantum yield (QY). By optimizing synthesis conditions, including the reaction temperature, flow rate, ethylenediamine dosage, and porosity of copper fibers, the N-CDs with a high PL QY of 73% were achieved. The PL QY of N-CDs was two times higher with copper fibers than without. The interrelations between the copper fibers with different porosities and the N-CDs were investigated using X-ray photoelectron spectroscopy (XPS) and Fourier Transform infrared spectroscopy (FTIR). The results demonstrate that the elemental contents and surface functional groups of N-CDs are significantly influenced by the porosity of copper fibers. The N-CDs can be used to effectively and selectively detect Hg2+ ions with a good linear response in the 0~50 μM Hg2+ ions concentration range, and the lowest limit of detection (LOD) is 2.54 nM, suggesting that the N-CDs have great potential for applications in the fields of environmental and hazard detection. Further studies reveal that the different d orbital energy levels of Hg2+ compared to those of other metal ions can affect the efficiency of electron transfer and thereby result in their different response in fluorescence quenching towards N-CDs.
“…The limit of detection (LOD) is 19 nM at a signal-tonoise ratio of 3. As shown in Table S1 (ESI †), the detection limit obtained with the present method was lower than those obtained by carbon dots (CDs), 35 F doped CDs (F-CDs), 36 N doped CDs (N-CDs), 37 N and S co-doped CDs (N, S-CDs), 38,39 N doped GQDs (N-GCDs), 34 sulfur and nitrogen co-doped GQDs (S,N-GQDs), 40 and N-GQDs, 41 but higher than that obtained using Rhodamine B assisted GQDs (RhB-GQDs) 42 and N and S co-doped GQDs (N, S-GQDs). 43 The application of the as-prepared uorescent sensor for detection of Hg 2+ in environmental samples (lake water) was investigated ( Table 1).…”
Section: Fluorescent Turn-off Detection Of Hg 2+ Using N-gqds As Uormentioning
“…The as-synthesized CDs presented an LOD of 0.1 µM with a linear range from 0.5 to 40 µM. Li et al [ 161 ] found that simultaneous doping of nitrogen and sulfur in CDs can effectively encourage the electron transfer and coordination interactions between the CDs and Hg 2+ ions. In their report, the nitrogen and sulfur co-doped CDs served as a label-free Hg 2+ fluorescence nanoprobe with an LOD of 2 µM.…”
Section: Sensing Applicationsmentioning
confidence: 99%
“…The fluorescence intensity ratio of both emission bands was linear in the Hg 2+ concentration range from 0 to 40 µM with a low LOD of 9 nM. Table 4 summarizes some of the research works related to Hg 2+ ion sensing using CD-based sensors [ 22 , 157 , 158 , 160 , 161 , 165 – 177 ]. Fig.…”
Over the past decade, carbon dots have ignited a burst of interest in many different fields, including nanomedicine, solar energy, optoelectronics, energy storage, and sensing applications, owing to their excellent photoluminescence properties and the easiness to modify their optical properties through doping and functionalization. In this review, the synthesis, structural and optical properties, as well as photoluminescence mechanisms of carbon dots are first reviewed and summarized. Then, we describe a series of designs for carbon dot-based sensors and the different sensing mechanisms associated with them. Thereafter, we elaborate on recent research advances on carbon dot-based sensors for the selective and sensitive detection of a wide range of analytes, including heavy metals, cations, anions, biomolecules, biomarkers, nitroaromatic explosives, pollutants, vitamins, and drugs. Lastly, we provide a concluding perspective on the overall status, challenges, and future directions for the use of carbon dots in real-life sensing.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
