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Copper nanoclusters @ nitrogen-doped carbon quantum dots-based ratiometric fluorescence probe for lead (II) ions detection in porphyra
摘要： A novel ratiometric fluorescence probe was proposed for detecting lead (II) ions (Pb2+) in porphyra, the approach was based on copper nanoclusters and nitrogen-doped carbon quantum dots (CuNCs-CNQDs). In this probe, the CuNCs delivered the response signal, the fluorescence of which was enhanced by Pb2+ due to the aggregation-induced emission enhancement (AIEE) between Pb2+ and CuNCs. The CNQDs provided the self-calibration signal, whose fluorescence remained almost unchanged in coexistence with Pb2+. According to the change of fluorescence intensity ratio between the fluorophores, CuNCs–CNQDs nanohybrid was used as ratiometric probes for the sensitive detection of Pb2+ in the range of 0.010 to 2.5 mg L-1, with a detection limit of 0.0031 mg L-1. Finally, the probe was successfully applied to detect Pb2+ in porphyra with relative standard deviations (RSDs) lower than 5%. This study provides a straightforward, stable, and sensitive approach for detecting Pb2+ in porphyra.
关键词： Lead (II) ions,Ratiometric fluorescence probe,Aggregation-induced emission enhancement,Copper nanoclusters,Nitrogen-doped carbon quantum dots
更新于2025-09-23 15:21:01
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Fluorescent-Nitrogen-Doped Carbon Quantum Dots Derived from Citrus Lemon Juice: Green Synthesis, Mercury(II) Ion Sensing, and Live Cell Imaging
摘要： In this study, we report a green and economical hydrothermal synthesis of fluorescent-nitrogen-doped carbon quantum dots (NCQDs) using citrus lemon as a carbon source. The prepared NCQDs possess high water solubility, high ionic stability, resistance to photobleaching, and bright blue color under ultraviolet radiation with a high quantum yield (～31%). High-resolution transmission electron microscopy (HRTEM) results show that the prepared NCQDs have a narrow size distribution (1?6 nm) with an average particle size of 3 nm. The mercury ion (Hg2+) sensing efficiency of the NCQDs was studied, and the result indicated that the material has high sensitivity, high precision, and good selectivity for Hg2+. The limit of detection (LOD) is 5.3 nM and the limit of quantification (LOQ) is 18.3 nM at a 99% confidence level. The cytotoxicity was evaluated using MCF7 cells, and the cell viabilities were determined to be greater than 88% upon the addition of NCQDs over a wide concentration range from 0 to 2 mg/mL. Based on the low cytotoxicity, good biocompatibility, and other revealed interesting merits, we also applied the prepared NCQDs as an effective fluorescent probe for multicolor live cell imaging.
关键词： mercury(II) ion sensing,citrus lemon juice,green synthesis,live cell imaging,fluorescent-nitrogen-doped carbon quantum dots
更新于2025-09-23 15:19:57
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S, N-doped carbon quantum dots enhanced Luminol-Mn(IV) chemiluminescence reaction for detection of uric acid in biological fluids
摘要： Herein, S, N doped carbon quantum dots (S, N- CQDs) were prepared by a simple hydrothermal method and characterized by transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDS) and Fourier transform infrared (FTIR) analysis. The influence of as-prepared CQDs was studied on the luminol- Mn(IV) CL reaction. The results indicated that S, N-CQDs remarkably increase the CL intensity of this reaction (about 13 fold). Furthermore, it was found that the CL intensity of S,N-CQDs–luminol-Mn(IV) system was significantly declined by uric acid. We exploited the amplified CL system to design a novel probe for the detection of uric acid. The CL intensity of S,N-CQDs–luminol-Mn(IV) reaction was proportional to the logarithm of uric acid concentration in the range of 0.05 to 1.5 μM, with a limit of detection of 17 nM. Based on these results, a sensitive and straightforward CL method was developed for the analysis of uric acid in biological fluids with satisfactory results.
关键词： Uric acid,sulfur-nitrogen doped carbon quantum dots,Chemiluminescence,Mn (IV)
更新于2025-09-23 15:19:57
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Precise Surface State Control of Carbon Quantum Dots to Enhance Charge Extraction for Solar Cells
摘要： Dye‐sensitized solar cells are regarded as promising candidates to resolve the energy and environmental issues in recent years, arising from their solution‐processable fabrication technology and high power conversion efficiency. However, there are still several problems regarding how to accelerate the development of this type of photovoltaics, including the limited light‐harvesting ability and high‐production cost of molecular dye. In the current work, we have systematically studied the role of nitrogen‐doped carbon quantum dots (N‐CQDs) as co‐sensitizers in traditional dye sensitized solar cells. A series of N‐CQDs have been prepared by employing chitosan as a precursor via one‐pot hydrothermal technology for various times, demonstrating a maximized efficiency as high as 0.089% for an only N‐CQDs‐based device. Moreover, the co‐sensitized solar cell based on N719 dye (C58H86N8O8RuS2) and optimized N‐CQDs shows significantly enhanced performance, yielding a solar‐to‐electric conversion efficiency of up to 9.15% under one standard sun (AM 1.5G) irradiation, which is much higher than the 8.5%‐efficiency of the controlled device without N‐CQDs. The matched characteristics of energy level, excellent up‐convention, and FRET (F?rster resonance energy transfer) abilities of N‐CQDs are responsible for their improved power conversion efficiency.
关键词： light absorption,up‐convention,nitrogen‐doped carbon quantum dots,co‐sensitized solar cell
更新于2025-09-19 17:13:59
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Layer by Layer Self-Assembly of Hollow Nitrogen-Doped Carbon Quantum Dots on Cationized Textured Crystalline Silicon Solar Cells for Efficient Energy Down-Shift
摘要： Enhancing the efficiency of crystalline silicon solar cell (c-Si SC) by coating the energy shifting layer of quantum dots (QDs) is a recent approach to efficiently utilize the high energy spectrum of light. Carbon QDs are an attractive candidate for such applications, however, small Stokes shift and non-uniform coating due to high aggregation are the bottlenecks to fully utilize their potential. For the purpose, here we propose a layer by layer self-assembled uniform coating of ecofriendly red-emissive hollow nitrogen-doped carbon QDs (NR-CQDs), as an efficient energy-down shifting layer. A unique hollow and conjugated structure of NR-CQDs was designed to achieve a large Stokes shift (UV excited - red emission), with a quantum yield (QY) comparable to Cd/Pb QDs. Highly uniform coating of intrinsically negatively charged NR-CQDs on c-Si SCs was achieved by cationizing the c-Si SC by Bovine serum albumin (BSA), under mildly acidic conditions. By opposite charge assisted self-assembled over-layer, the short-circuit current density (Jsc) and power-conversion efficiency was increased by 5.8%, which is attributed to the large Stokes shift (255 nm) and high QY. Blue-emissive undoped-carbon QDs were synthesized for comparison with the proposed NR-CQDs, to elucidate the significance of the novel proposed structure.
关键词： energy-downshift,crystalline silicon solar cells,layer by layer self-assembly,Nitrogen-doped carbon quantum dots,cationization,photoluminescence
更新于2025-09-19 17:13:59
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Red-emissive nitrogen doped carbon quantum dots for highly selective and sensitive fluorescence detection of the alachlor herbicide in soil samples
摘要： Red-emissive nitrogen doped carbon quantum dots (N-CQDs) were synthesized by a facile and efficient microwave-assisted hydrothermal treatment of p-phenylenediamine (p-PD), and then applied for the highly selective and sensitive fluorescence detection of the alachlor herbicide in soil samples. The synthesized N-CQDs exhibited strong red emission with a 27.6% quantum yield (QY) and high stability. Under the optimized experimental conditions, the as-prepared red-emissive N-CQDs were employed as a fluorescent probe to successfully detect trace alachlor, and their fluorescence presented a good linear decline with the increase of the alachlor concentration from 0.005 to 150 mM with a limit of detection of 0.2 nM. The N-CQDs as a fluorescent probe were used for the detection of alachlor in soil samples with satisfactory recoveries ranging from 86.6–114.3%, indicating that they were a promising fluorescent probe for highly selective and sensitive determination of alachlor.
关键词： soil samples,Red-emissive nitrogen doped carbon quantum dots,fluorescence detection,alachlor herbicide
更新于2025-09-16 10:30:52
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Ethanol-Precipitation-Assisted Highly Efficient Synthesis of Nitrogen-Doped Carbon Quantum Dots from Chitosan
摘要： Nitrogen-doped carbon quantum dots (NCQDs) were prepared from chitosan through a hydrothermal reaction. When ethanol precipitation was used as the puri?cation method, a high product yield of 85.3% was obtained. A strong blue ?uorescence emission with a high quantum yield (QY) of 6.6% was observed from the NCQD aqueous solution. Physical and chemical characteristics of the NCQDs were carefully investigated by transmission electron microscopy (TEM), X-ray di?raction (XRD), Fourier transform infrared spectra (FTIR), Raman spectra, X-ray photoelectron spectroscopy (XPS), and transient ?uorescence spectra. Experimental results showed that diameters of the NCQDs were in the range of 2?10 nm. The carbon quantum dots possess good water dispersibility and precipitation by ethanol. When used for metal ion detection, the detection limit of the NCQDs for Fe3+ was as low as 1.57 μM. This work proposed a facile method to synthesize NCQDs from chitosan with high yield and demonstrated that carbon quantum dots derived from chitosan were promising for ion detection.
关键词： ethanol precipitation,metal ion detection,chitosan,hydrothermal reaction,Nitrogen-doped carbon quantum dots
更新于2025-09-12 10:27:22
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Nitrogen-Doped Carbon Quantum Dots-Decorated Mg-Al Layered Double Hydroxide Supported Gold Nanocatalysts for Efficient Base-free Oxidation of Benzyl Alcohol
摘要： A nitrogen-doped carbon quantum dots (NCDs)-decorated Mg-Al layered double hydroxide (MgAl-LDH) supported gold nanoparticles (NPs) was employed in the aerobic oxidation of benzyl alcohol under solvent-free and base-free conditions. Comprehensive characterizations revealed that the decoration of NCDs improved surface basicity of NCD/MgAl-LDH and was beneficial to the stabilization of gold NPs. Compared with MgAl-LDH supported gold catalyst, Au/NCD/MgAl-LDH showed much better catalytic activity, along with a turnover frequency of about 20175 h-1 for benzyl alcohol conversion. The promoted catalytic efficiency of the NCD/MgAl-LDH supported Au catalyst was mainly corelated with unique cooperation between surface hydroxyl arrays at the brucite-like lattice of MgAl-LDH matrix and highly dispersed NCDs, thereby favoring the adsorption and activation of alcohol hydroxyls. Furthermore, compared with Au/MgAl-LDH, Au/NCD/MgAl-LDH showed better structural stability, due to the strong Au-NCDs interactions. The primary finding opens a promising approach to develop other highly efficient metal-base catalysts applied in various base-catalyzed heterogenous reactions.
关键词： Surface metal-base cooperation,Layered double hydroxide,Au nanoparticles,Nitrogen-doped carbon quantum dots,Oxidation
更新于2025-09-12 10:27:22
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Paper sensor of curcumin by fluorescence resonance energy transfer on nitrogen-doped carbon quantum dot
摘要： Paper Sensor detection methods are attractive in wide analytical applications. Presented herein is a paper sensor and ?uorescence methods that was ?rstly developed to detect curcumin (Cur) based on ?uorescence resonance energy transfer (FRET) between nitrogen-doped carbon quantum dots (NCQDs) and Cur. The facile ?uorescent method was demonstrated to detect Cur in the range of 0e2600 mM with a detection limit of 0.13 mM. And facile paper sensor of Cur was fabricated and displayed at concentration of 0 mM, 100 mM, 200 mM, 300 mM, 400 mM, 500 mM and 600 mM, respectively. In additions, it was realized for determination of Cur in real samples including orange juice and curry solution. Compared with the reported methods, the present method is simple, rapid and sensitive for detecting Cur.
关键词： Nitrogen-doped carbon quantum dots (NCQDs),Curcumin (Cur),Fluorescence resonance energy transfer (FRET),Paper-based sensor
更新于2025-09-11 14:15:04