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Directed Nanoscale Self-assembly of Natural Photosystems on Nitrogen-doped Carbon Nanotubes for Solar Energy Harvesting
摘要： Natural photosystems (PSs) have received much attention as a biological solar energy harvester because of their high quantum efficiency for energy transfer. However, the PSs hybridized with solid electrodes exhibit low light-harvesting efficiencies because of poor interface properties and random orientations of PSs, all of which interfere with efficient charge extraction and transfer. Herein, we report the linker-free, oriented self-assembly of natural PSs with nitrogen-doped carbon nanotubes (NCNTs) via electrostatic interaction. Protonated nitrogen-doped sites on the NCNTs facilitate spontaneous immobilization of the negatively charged stroma side of PSs, which provides a favorable orientation for electron transfer without electrically insulating polymer linkers. The resulting PS/NCNT hybrids exhibit a photocurrent density of 1.25 ± 0.08 μA cm-2, which is much higher than that of PS/CNT hybrids stabilized with polyethylenimine (0.60 ± 0.01 μA cm-2) and sodium dodecyl sulfate (0.14 ± 0.01 μA cm-2), respectively. This work emphasizes the importance of the linker-free assembly of PSs into well-oriented hybrid structures to construct an efficient light-harvesting electrode.
关键词： Light-harvesting,Electrostatic interaction,Photosystems,Nitrogen-doped carbon nanotubes,Self-assembly
更新于2025-11-14 15:29:11
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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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Mo-doped Zn, Co Zeolitic-Imidazolate Framework-derived Co9S8 Quantum Dots and MoS2 Embedded in Three-Dimensional Nitrogen Doped Carbon Nano???ake Arrays as an Efficient Trifunctional Electrocatalysts for ORR, OER and HER
摘要： Herein, we first propose a facile strategy to synthesize Co9S8 and MoS2 nanocrystals embedded in porous carbon nanoflake arrays supported on carbon nanofibers (Co9S8-MoS2/N-CNAs@CNFs) by the pyrolysis of Mo-doped Zn, Co zeolitic-imidazolate framework grown on carbon nanofibers and subsequent sulfuration. The electrocatalyst shows high and stable electrocatalytic performance, with half-wave potential of 0.82 V for ORR and overpotential at 10 mA cm-2 for OER (0.34 V) and HER (0.163 V), which outperform the metal-organic frameworks-derived transition metal sulfide catalysts reported so far. Furthermore, the Co9S8-MoS2@N-CNAs@CNFs are employed as an air cathode in a liquid-state and all-solid-state zinc-air battery, presenting high power density of 222 mW cm-2 and 96 mW cm-2, respectively. Such excellent catalytic activities are mainly owing to the unique three-dimensional structure and chemical compositions, optimal electronic conductivity, adequate surface area and the abundance of active sites. Thus, this work provides an important method for designing other metal-organic frameworks derived three-dimensional structural sulfide quantum dot multifunctional electrocatalyst for wider application in highly efficient catalysis and energy storage.
关键词： zeolitic-imidazolate framework,Co9S8 quantum dots,MoS2,nitrogen-doped carbon nanoflakes arrays,Zn-air battery,trifunctional electrocatalysts
更新于2025-09-23 15:19:57
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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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Determination of chondroitin sulfate in synovial fluid and drug by ratiometric fluorescence strategy based on carbon dots quenched FAM-labeled ssDNA
摘要： Chondroitin sulfate (CS) plays an increasingly important role in clinical settings and pharmacy quality control. However, sensitive and simple methods for CS detection remain limited. In this work, positively charged nitrogen doped carbon dots (P-NCDs) with internal luminescence and quenching property to FAM-labeled random-sequence ssDNA (F-ssDNA) were prepared by a simple heating method. P-NCDs attached and quenched F-ssDNA through electrostatic interaction to form the system of P-NCDs and F-ssDNA (P-NCDs/F-ssDNA) with retained fluorescence intensity of P-NCDs. The highly negatively charged CS reacted electrostatically with P-NCDs and then replaced F-ssDNA in P-NCDs/F-ssDNA to recover the fluorescence intensity of the original quenched F-ssDNA while retaining the internal fluorescence intensity of P-NCDs. Thus, by using restored F-ssDNA as the signal controlled by adding CS to P-NCDs/F-ssDNA, a ratiometric fluorescence strategy based on the retained fluorescence of P-NCDs as reference signal was fabricated through synchronous fluorescence spectrometry for the sensitive detection of CS. Under the optimal experimental conditions, a linear equation for CS was obtained for CS concentration within the range of 0.05–2.0 μg/mL. The method was also successfully applied for the accurate determination of CS in joint fluid samples of arthritic patients, chondroitin sulfate tablets, and chondroitin sulfate eye drops, suggesting its appreciable application potential in the clinic.
关键词： Positively charged nitrogen doped carbon dots (P-NCDs),Chondroitin sulfate,Synchronous fluorescence spectrometry,Ratiometric fluorescence strategy,Synovial fluid
更新于2025-09-23 15:19:57
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Ratiometric fluorometric determination of silver(I) by using blue-emitting silicon- and nitrogen-doped carbon quantum dots and red-emitting N-acetyl-L-cysteine-capped CdTe quantum dots
摘要： A ratiometric fluorometric assay for silver(I) is described. The method makes use of a dually emitting quantum dot hybrid, which is composed of (a) blue-fluorescent silicon- and nitrogen-doped carbon quantum dots (CQDs), and (b) of red-emitting CdTe quantum dots (QDs) capped with N-acetyl-L-cysteine. The red-emitting CdTe QDs undergo strong and specific quenching by Ag(I), whereas the blue-emitting N,Si-CQDs are not quenched. The two kinds of QDs are mixed and used as a ratiometric fluorescent probe. A linear relationship is found between the log of intensities [(I608/I441)0/(I608/I441)] and the concentration of Ag(I) in the range from 5.0–1000 nM, and the limit of detection (at S/N = 3) is 1.7 nM. Possible interferents (including 17 general metal ions, 12 anions and fulvic acid) do not interfere with the determination. The assay was successfully used for the determination of Ag(I) in surface water and wastewater samples. The fluorescence quenching mechanism of the ratiometric assay system was also discussed in detailed.
关键词： Fluorescence quenching mechanism,Surface water,Nitrogen-doped carbon dots,Silver ions,Silicon-doped carbon dots,Wastewaters,3-Aminopropyltriethoxysilane functionalized carbon dots,Quenching efficiency,Dual-emission quantum dots hybrid,Fluorescent probe
更新于2025-09-19 17:13:59
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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