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Novel conducting PVA/Carbon quantum dots (CQDs) nanocomposite for high anti-electromagnetic wave performance
摘要： Novel conductive PVA/CQDs nanocomposite films were synthesized through the casting technique for the electromagnetic (EM) wave protection at microwave band. The surface morphology, thermal and mechanical properties were briefly studied. The SEM micrograph showed an excellent distribution, dispersion and a high adhesion property of the CQDs in the PVA chains. Also, DSC analysis showed an increase in the glass temperature (Tglass) from 83.2 °C for fresh PVA to 95.4 °C for 8 wt% of CQD and the increase in melting temperature from 215 °C for fresh PVA to 227.7 °C for the same CQDs concentration. It was found that Young's modulus is directly proportional to CQD nano-particles concentration in the nano-composites from 0.14 GPa for fresh PVA to 4.48 GPa for 8 wt% of CQDs. It was found that the strength at break increases, but the elongation declines with the increase of CQDs nano-particles. The EM shielding effectiveness (SE) of (PVA/CQDs) nanocomposite is measured in the microwave frequency range, and it is found around 36.8 dB with the CQDs concentration (8 wt%). Finally, the PVA/CQDs nano-composite is of promising potential applications in electronics and microwave devices at an affordable cost.
关键词： PVA,Mechanical properties,Electromagnetic shielding,Thermal properties,CQDs nano-particles
更新于2025-09-19 17:13:59
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An ultra-selective fluorescence method with enhanced sensitivity for the determination of manganese (VII) in food stuffs using carbon quantum dots as nanoprobe
摘要： A novel fluorescence method was for the first time established for the efficient determination of permanganate (Mn(VII)) based on sulfur, chlorine and nitrogen co-doped carbon quantum dots (S,Cl,N-CQDs). The S,Cl,N-CQDs was prepared via a fast and simple acid-base neutralization method. The fluorescence of S,Cl,N-CQDs could be dramatically quenched by Mn(VII) ascribed to a combination of inner filter effect (IFE) and dynamic quenching. Under the optimal working conditions, the S,Cl,N-CQDs-based nanoprobe exhibited high selectivity and sensitivity towards Mn(VII) sensing. A good linear Stern-Volmer equation was obtained for Mn(VII) in a wide concentration range of 0.05–110 μM with a detection limit as low as 12.8 nM. The proposed fluorescence method also exhibits additional advantages of great simplicity, fast in analysis and low cost. The as-fabricated fluorescent nanoprobe was successfully applied for the determination of Mn(VII) monitoring in complex food matrix.
关键词： Cl,fluorescence quenching,Mn(VII),S,food samples,N-CQDs
更新于2025-09-19 17:13:59
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Photocatalytic activation of peroxymonosulfate by surface-tailored carbon quantum dots
摘要： In this study, carbon quantum dots (CQDs) were synthesized by a low-cost and scalable approach and the oxygen functional groups were fine-tuned by chemical post-treatment. It was found that the CQDs could be applied as visible-light-responsive photocatalysts for activation of peroxymonosulfate (PMS) and remediation of aqueous organic dyes. Phenylhydrazine modified CQDs (CQDs-PH) presented high efficiency for degradation of methylene blue due to selective removal of carboxylic groups and inhibited recombination of photogenerated electron-hole pairs. The effects of catalyst dosage, species and concentrations of dyes, and initial pH values on the photodegradation efficiency were systematically investigated and the alkaline condition facilitates the separation of photoinduced charge carriers and promotes the dye decoloration. The reactive oxygen species produced in the photocatalysis were identified by radical quenching tests and the mechanism was elucidated. Superoxide radicals were generated from PMS activation via electron transfer from CQDs and played the primary role for organic oxidation. In addition, photogenerated holes on the valence band of CQDs also participated in the dye decomposition.
关键词： peroxymonosulfate,superoxide radicals,Photocatalysis,oxygen groups,carbon quantum dots (CQDs)
更新于2025-09-19 17:13:59
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Inverted Si:PbS Colloidal Quantum Dots Heterojunction Based Infrared Photodetector
摘要： Silicon and PbS colloidal quantum dots heterojunction photodetector combines the advantages of Si device and PbS CQDs, presenting a promising strategy for infrared light detecting. However, the construction of high quality CQDs:Si heterojunction remains to be a challenge. In this work, we introduce an inverted structure photodetector based on n-type Si and p-type PbS CQDs. Compared with the existing normal structure photodetector with p-type Si and n-type PbS CQDs, it has lower energy band offset which provides higher efficient charge extraction for device. With the help of Si wafer surface passivation and the Si doping density optimization, the device delivers a high detectivity of 1.47×1011 Jones at 1540 nm without working bias, achieving the best performance in Si/PbS photodetectors now. This work provides a new strategy to fabricate low cost high performance PbS CQDs photodetector compatible with silicon arrays.
关键词： PbS CQDs,heterojunction,silicon,photodetector,ROICs
更新于2025-09-19 17:13:59
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Nitrogen-doped CQDs to enhance the power conversion efficiency of perovskite solar cells via surface passivation
摘要： In this study, nitrogen doped CQDs (N-CQDs), as a novel additive, were successfully synthesized and characterized by XPS, TEM and UVeVis spectrometry techniques. Importantly, we introduced N-CQDs in CH3NH3PbI3 solar cells. The results indicated that nonradiative charge back recombination decreased and the trap states in the absorber layer were passivated when N-CQDs was used an additive in CH3NH3PbI3 solution. Additionally, the morphological characterization results indicated that the crystallization problems and defects on perovskite surfaces can be easily resolved by N-CQDs additive in perovskite solution. A significant improvement in power conversion efficiency at a yield of 14% is achieved by doping of 3 vol% of N-CQDs, thanks to enhancement of charge transport properties due to the morphological and electrical changes. Herein, we propose an effective and novel additive for the fabrication of high efficiency perovskite solar cell, which can be seen that this method is simple.
关键词： Film coverage,N-CQDs,Perovskite solar cells,Charge transport properties
更新于2025-09-19 17:13:59
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Controlled synthesis and photocatalytic performance of biocompatible uniform carbon quantum dots with microwave absorption capacity
摘要： Carbon quantum dots (CQDs) were successfully prepared via a facile microwave-assisted method combined with a controlled drainage time using glucose as the carbon source. XRD analysis, FT-IR spectroscopy, UV spectroscopy, XPS, and PL spectroscopy were performed to characterize the structures and properties of the samples. The results showed that the average particle size of the prepared CQDs was about 2 nm, and there were two UV absorption at the wavelengths of 228 nm and 280 nm, respectively, corresponding to the π-π* transition of C=C (atomic group) and the n-π* transition of the oxygen containing group (C=O) on the surface of the carbon core. According to the unique optical and microwave absorption properties of the CQDs, a suitable photocatalytic system, namely, a microwave electrodeless discharge lamp (MEDL) system was used. In the MEDL system, the degradation rate of rhodamine B (RhB, 50mL, 30 mg L-1) by 0.02 g CQDs-2 in 10 min could reach 85.79 %. The photocatalytic activity of CQDs-2 was about twice that of P25. In addition, the biocompatibility of the CQDs was investigated, which revealed that the CQDs could be absorbed by microorganisms as a carbon source. The prepared CQDs are a promising environmentally friendly photocatalyst.
关键词： biocompatibility,microwave,photocatalytic,CQDs
更新于2025-09-19 17:13:59
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Highly Sensitive and Selective Detection of 2,4-Dinitrophenol by a Fluorescent Amine-Functionalized Carbon Quantum Dot@Metal-Organic Framework
摘要： Herein, we fabricate a composite fluorescence sensor by integrating amine-functionalized carbon quantum dots (amine-CQDs) and a zirconium-based metal-organic framework (UiO-67) using a post-synthetic modification approach, and employ the resulting amine-CQDs@UiO-67 composite as a platform for highly selective and sensitive detection of 2,4-dinitrophenol (DNP). In particular, UiO-67 acts as an adsorbent for the selective capture and enrichment of DNP molecules, whereas amine-CQDs serve as functional monomers for selective and sensitive DNP sensing.
关键词： amine-CQDs@UiO-67,luminescence,MOFs,nanocomposites
更新于2025-09-16 10:30:52
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Solution-processed P3HT:PbS based NIR Photodetector with FET Configuration
摘要： A near-infrared (NIR) solution-processed photodetector based on a mixture of PbS colloidal quantum dots (CQDs) and Poly(3-hexylthiophene) (P3HT) was presented. In a reverse field-effect transistor (FET) device configuration Au(S,D)/P3HT:PbS/PMMA/Al(G), uniform-sized and well-dispersed PbS CQDs were employed as NIR absorbing materials in the active layer. Meanwhile, the poly(methyl methacrylate) (PMMA) dielectric layer could be seen as an encapsulation to enhance the device stability. Herein, High “on/off” current ratio (Ion/Ioff) of 104 was obtained in dark, and the maximum photosensitivity (P) of 947 was gotten under 200 mW/cm2 980 nm illumination. When the irradiance reduced to 0.1 mW/cm2, the responsivity (R) and detectivity (D?) of the NIR photodetector reached 9.4 mA/W and 2.5×1011 Jones, respectively. Therefore, the P3HT:PbS hybrid FET-based NIR photodetector had shown both relatively high electrical and detecting performance, which provided an experimental foundation and method for the next fabrication of medical infrared detectors and sensors.
关键词： PbS colloidal quantum dots (CQDs),Near-infrared (NIR) photodetector,Poly(3-hexylthiophene) (P3HT),Field-effect transistor (FET)
更新于2025-09-16 10:30:52
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Enhanced photocatalytic activity of ZnO sensitized by carbon quantum dots and application in phenol wastewater
摘要： This work reports on preparation of ZnO composites sensitized by carbon quantum dots (CQDs) and its photocatalytic degradation on phenol under visible-light illumination. With the help of tools such as transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectra, X-ray photoelectron spectroscopy (XPS), UV–vis diffusive reflectance spectra (UV–Vis DRS) and gas chromatograph-mass spectrometer (GC-MS), successful synthesis of ZnO composites sensitized by CQDs has been confirmed, which extend the spectral response range of the procatalyst to the visible region enhancing the utilization of sunlight. Meanwhile, transient photocurrent response and Nyquist plot analysis were further proved the increase in carrier separation efficiency of the procatalyst. The photocatalytic ability of the composites was measured by XPA-7 photocatalytic instrument with using phenol as simulate pollutants. And the photocatalytic reaction mechanism was also revealed by the Mott-Schottky plot, band structure and trapping experiments of active species. The results exhibit that the photocatalytic performance of ZnO composites sensitized by CQDs is 60% higher than that of pure ZnO with good stability and reusability, whose utilization has almost no significant change after 10 cycles.
关键词： ZnO,Phenol,Photocatalysis,L-CQDs,Composites
更新于2025-09-16 10:30:52
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Carbon Quantum Dots (CQDs) Decorated Bi2O3-x Hybrid Photocatalysts with Promising NIR-Light-Driven Photodegradation Activity for AO7
摘要： In this work, Bi2O3-x with surface oxygen vacancies was prepared through the NaBH4 reduction of Bi2O3. After that, carbon quantum dots (CQDs) were deposited onto the surface of the Bi2O3-x to obtain a series of the CQDs/Bi2O3-x composites. The HRTEM and XPS characterizations of the CQDs/Bi2O3-x composites suggest that the thickness of surface oxygen vacancies could be adjusted by changing the concentration of NaBH4 solution, and the intimate contact between CQDs and the Bi2O3-x is achieved. Acid orange 7 (AO7) was adopted as the target reactant for investigating the photocatalytic degradation activities of the CQDs/Bi2O3-x composites under simulated sunlight and NIR light irradiation. It is found that the photocatalytic activities of the samples are closely related to the concentration of NaBH4 and content of CQDs. The Bi2O3-x samples exhibit enhanced simulated-sunlight-driven photocatalytic activity compared with Bi2O3. Specifically, the optimal degradation efficiency of AO7 is achieved over the 3R-Bi2O3-x (concentration of NaBH4: 3 mmol/L), which is 1.38 times higher than the degradation AO7 efficiency over Bi2O3. After the decoration of the 3R-Bi2O3-x surface with CQDs, the simulated-sunlight-driven photocatalytic activity of the CQDs/Bi2O3-x composite could be further enhanced. Among the samples, the 15C/3R-Bi2O3-x sample reveals the highest photocatalytic activity, leading to an AO7 degradation percentage of ~97% after 60 min irradiation. Different from Bi2O3 and the 3R-Bi2O3-x, the 15C/3R-Bi2O3-x sample also exhibits near-infrared (NIR)-light-driven photocatalytic degradation activity. In addition, the intrinsic photocatalytic activity of CQDs/Bi2O3-x composite was further confirmed by the degradation of phenol under simulated sunlight and NIR light irradiation. The photocurrent response and electrochemical impedance spectroscopy (EIS) measurements confirm the efficient migration and separation of photogenerated charges in the CQDs/Bi2O3-x samples. The ?OH and h+ are proved to be the main reactive species in the simulated sunlight and NIR light photocatalytic processes over the CQDs/Bi2O3-x composites. According to the above experiments, the photocatalytic degradation mechanisms of the CQDs/Bi2O3-x composites under simulated sunlight and NIR light illumination were proposed.
关键词： photocatalytic,composites,oxygen vacancies,CQDs,Bi2O3
更新于2025-09-12 10:27:22