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Liquefied petroleum gas sensing properties of ZnO/PPy/PbS QDs nanocomposite prepared by self-assembly combining with SILAR method
摘要： In this paper, a high-performance liquefied petroleum gas (LPG) sensor based on zinc oxide/polypyrrole/lead sulfide quantum dots (ZnO/PPy/PbS QDs) nanocomposite film was demonstrated, which was fabricated by layer-by-layer (LbL) self-assembly and successive ionic layer adsorption and reaction (SILAR) technique. The nanostructure features of the as-prepared ZnO/PPy/PbS nanocomposite film were confirmed by various characterization techniques. The room temperature gas-sensing investigation of the ZnO/PPy/PbS QDs nanocomposite sensor was performed against LPG gas in a wide concentration range. The experimental results showed an outstanding response for LPG sensing at room temperature compared with previous reports, the response can reach 45.47% at 1000 ppm LPG. And it also demonstrated good selectivity and excellent repeatability. The sensing mechanism of the PPy/ZnO/PbS QDs nanocomposite film gas sensor is owing to the p-n heterojunction created at the ZnO/PPy interface, as well as much more active adsorption sites.
关键词： polypyrrole,liquefied petroleum gas,zinc oxide,lead sulfide quantum dots,SILAR method
更新于2025-11-14 17:04:02
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Sulfur doped carbon nitride quantum dots with efficient fluorescent property and their application for bioimaging
摘要： Heteroatom doping can drastically alter electronic characteristics of carbon nitride quantum dots, thus resulting in unusual properties and related applications. Herein, we used sulfur as the doping element and investigated the influence of doping on the electronic distribution of carbon nitride and the corresponding fluorescent property. A simple synthetic strategy was applied to prepare sulfur-doped carbon nitride (S-g-C3N4) quantum dots through ultrasonic treatment of bulk S-g-C3N4. Characterization results demonstrated that the prepared S-g-C3N4 quantum dots with an average size of 2.0 nm were successfully prepared. Fluorescent properties indicated that S-g-C3N4 quantum dots have an emission peak at 460 nm and cover the emission spectra region up to 550 nm. Furthermore, the fluorescent intensity is greatly increased due to the sonication of bulk S-g-C3N4 into quantum dots. As a result, S-g-C3N4 quantum dots not only show a blue cell imaging, but have a bright green color. Therefore, S-g-C3N4 quantum dot is a promising candidate for bioimaging benefiting from the efficient fluorescent property, good biocompatibility, and low toxicity.
关键词： Doped carbon nitride,Fluorescent property,In vitro cytotoxicity,Quantum dots,Bioimaging
更新于2025-11-14 17:04:02
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In Situ Microwave-Assisted Fabrication of Hierarchically Arranged Metal Sulfide Counter Electrodes to Boost Stability and Efficiency of Quantum Dot-Sensitized Solar Cells
摘要： This study describes preparation of metal sulfide counter electrodes (CEs) through one-pot microwave-assisted route to improve power conversion efficiency (PCE) of quantum dot-sensitized solar cells at a lower cost. The CuS nanorods, Ni0.96S nanoparticles, and PbS nanocubes are synthesized and deposited in situ on fluorine-doped tin oxide substrate to serve as CEs without further post-treatment. Effects of several reaction parameters including sulfur precursor (Na2S, C2H5NS, CH4N2S), Cu concentration, reaction time, and choice of cation (Cu, Ni, Pb) on the CEs morphology, electrochemical characteristics, and PCE are studied. Furthermore, nanostructure formation and thin film growth are studied and correlated with PCE, from which morphology- and composition-performance relationships can be inferred. Hierarchically assembled nanorod CuS CEs exhibit higher electrochemical stability in the S2–/Sn2– redox reaction. Together with the efficient charge transfer and higher diffusion coefficient of polysulfide redox at the electrode/electrolyte interface, deduced from electrochemical impedance spectroscopy and Tafel analyses, a PCE of 8.32% is achieved for the CuS CE. The enhanced photovoltaic performance is ascribed to the 1D CuS nanorods forming a diffusive structure which decreases charge transfer impedance and facilitates regeneration of polysulfide redox leading to a higher short-circuit current density and fill factor.
关键词： In situ deposition,quantum dot-sensitized solar cells,counter electrode,CuS,microwave-assisted synthesis
更新于2025-11-14 17:04:02
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Hierarchical ZnO microspheres embedded in TiO2 photoanode for enhanced CdS/CdSe sensitized solar cells
摘要： Control of structural and compositional characteristics of photoanodes is a crucial step toward rapid transport of charges and high efficiency loading of dye or quantum dots in case of solar cell application. A hierarchical ZnO microspheres (ZMS) and TiO2 hybrid photoanode film was prepared for improved CdS/CdSe quantum dot sensitized solar cells (QDSCs). The addition of ZMS into TiO2 electrode films resulted in both increased short circuit current density (Jsc) and open circuit voltage (Voc). Such an improvement is ascribed to the increased light harvesting owing to scattering by ZMS and the reduced charge recombination due to the surface modification. TiO2/ZMS hybrid photoanode displays superior charge injection/transport performance due to the ZMS with unique hierarchical structure, providing charge transfer continuity and multiple electron transport channels for timely electron transport. As a result, the Jsc, Voc, and the photovoltaic conversion efficiency (PCE) were all remarkably enhanced with the insertion of hierarchical ZMS though varied appreciably with the amount of ZMS. Thus, the designed TiO2/ZMS heterostructure based QDSCs with an optimizing ZMS ratio of 20 wt% achieved a PCE of 5.99%, which is about 35% increase of the efficiency for the devices without ZMS (4.45%).
关键词： electron transport,ZnO microspheres,charge injection,quantum dot-sensitized solar cells,photoanode,light scattering
更新于2025-11-14 17:04:02
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Synthesis of ZnxCd1-xSe@ZnO Hollow Spheres in Different Sizes for Quantum Dots Sensitized Solar Cells Application
摘要： ZnxCd1-xSe@ZnO hollow spheres (HS) were successfully fabricated for application in quantum dot sensitized solar cells (QDSSCs) based on ZnO HS through the ion-exchange process. The sizes of the ZnxCd1-xSe@ZnO HS could be tuned from ~300 nm to ~800 nm using ZnO HS pre-synthesized by different sizes of carbonaceous spheres as templates. The photovoltaic performance of QDSSCs, especially the short-circuit current density (Jsc), experienced an obvious change when different sizes of ZnxCd1-xSe@ZnO HS are employed. The ZnxCd1-xSe@ZnO HS with an average size distribution of ~500 nm presented a better performance than the QDSSCs based on other sizes of ZnxCd1-xSe@ZnO HS. When using the mixture of ZnxCd1-xSe@ZnO HS with different sizes, the power conversion ef?ciency can be further improved. The size effect of the hollow spheres, light scattering, and composition gradient structure ZnxCd1-xSe@ZnO HS are responsible for the enhancement of the photovoltaic performance.
关键词： zinc oxide,alloyed quantum dots,sensitized solar cells,hollow spheres
更新于2025-11-14 17:04:02
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Short-chain ligand assisted synthesis of CH3NH3PbX3 (X = Cl, Br, I) perovskite quantum dots and improved morphology of CH3NH3PbBr3 thin films
摘要： Employing the short-chain C4H9NH3X (X = Cl, Br, I) compound as the unique capping agent, highly quality CH3NH3PbX3 (X = Cl, Br, I) perovskite quantum dots can be synthesized at room temperature in the open air, which possess high photoluminescence quantum yields and tunable emission in the range of 440-660 nm. Besides, C4H9NH3Br can also improve the morphology of CH3NH3PbBr3 thin films by spin-coating the N, N-dimerthylformamide solution of CH3NH3Br, C4H9NH3Br and PbBr2, making the thin film dense and compact, and improving its optical properties.
关键词： quantum dots,Perovskite,CH3NH3PbX3(Cl, Br, I),photoluminescence spectra,morphology
更新于2025-11-14 17:04:02
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Ligand Engineering for Improved All‐Inorganic Perovskite Quantum Dot‐MoS <sub/>2</sub> Monolayer Mixed Dimensional van der Waals Phototransistor
摘要： Combining intriguing physical properties of 2D crystals and intrinsically remarkable optical properties of halide perovskite quantum dots (QDs), the 0D–2D perovskite QD–based mixed dimensional van der Waals heterostructure (MvdWH) is considered as promising for optoelectronic applications. Even though the interfacial electronic structure of MvdWHs is sufficiently engineered to manipulate the charge carrier behavior, the issue of interfacial charge transfer efficiency originating from the residue ligands that are inevitably introduced by the QDs is still prominently remained. From this perspective, for the first time, a solution-processed surface ligand density control strategy is demonstrated to balance the QD surface passivation and the interfacial charge carrier extraction and injection efficiency in the 0D–2D MvdWH system. The accurate adjustment of ligand density outside QDs enables the subsequent modulation on interfacial charge carrier transfer efficiency from the aspect of electronic and optoelectronic properties. Furthermore, such kind of ligand engineering toward MvdWH interface is substantially demonstrated in a photogating mechanism–based phototransistor with an improved photoresponsivity as high as 1.13 × 105 A W?1. These results may push forward the evolution of 0D–2D mixed dimensional van der Waals optoelectronics.
关键词： mixed-dimensional van der Waals heterostructures,perovskite quantum dots,phototransistors,MoS2,ligand engineering
更新于2025-11-14 17:04:02
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Facile and one-step preparation carbon quantum dots from biomass residue and their applications as efficient surfactants
摘要： Using biomass residue as a source of carbon precursors, a pyrolysis method was used to prepare biomass-derived luminescent Carbon Quantum Dots (CQDs). The prepared CQDs exhibited excellent fluorescence and luminescence properties and fluorescence behaviors of CQDs acquired at different pyrolysis temperatures varied. Importantly, the CQDs showed superior surface activity and the styrene-in-water Pickering emulsion prepared using the CQDs as nano-sized surfactant was highly stable: the higher the pyrolysis temperature the better the stability of the emulsion. In addition, there was no stratification found in the emulsion which was stabilized by the CQD500 (CQDs prepared at 500 (cid:1)C) after holding for 72 hours. This research provided an approach for preparing the surfactants of nano-sized particles in large scale. The CQDs prepared using the proposed methods are expected to have a high number of potential applications.
关键词： biomass,nano-sized surfactant,Carbon Quantum Dots,stability,pickering emulsion
更新于2025-11-14 17:04:02
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The Size Effect of TiO2 Hollow Microspheres on Photovoltaic Performance of ZnS/CdS Quantum Dots Sensitized Solar Cell
摘要： Size controllable TiO2 hollow microspheres (HMS) were synthesized by a carbonaceous spheres (CS) template method. Based on TiO2 HMS, the ZnS/CdS quantum dots (QDs) were loaded to form a ZnS/CdS@TiO2 HMS photoanode for quantum dots sensitized solar cell (QDSSC). The size effects of TiO2 HMS on photovoltaic performance were investigated, and showed that TiO2 HMS with sizes ~560 nm produced the best short-circuit current density (Jsc) of 8.02 mA cm?2 and highest power conversion efficiency (PCE) of 1.83%, showing a better photovoltaic performance than any other QDSSCs based on TiO2 HMS with size ~330 nm, ~400 nm, and ~700 nm. The improvement of photovoltaic performance based on ~560 nm TiO2 HMS which can be ascribed to the enhanced light harvesting efficiency caused by multiple light reflection and strong light scattering of TiO2 HMS. The ultraviolet-visible (UV-vis) spectra and incident photo to the current conversion efficiency (IPCE) test results confirmed that the size of TiO2 HMS has an obvious effect on light harvesting efficiency. A further application of ~560 nm TiO2 HMS in ZnS/PbS/CdS QDSSC can improve the PCE to 2.73%, showing that TiO2 HMS has wide applicability in the design of QDSSCs.
关键词： titanium dioxide,quantum dots sensitized solar cells,hollow microspheres
更新于2025-11-14 17:04:02
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Determination of Thiourea by On–Off Fluorescence Using Nitrogen-Doped Graphene Quantum Dots
摘要： A thiourea-detecting fluorescence sensor with Hg2t as a switch was developed using nitrogen-doped graphene quantum dots (N-GQDs). The surface of N-GQDs had many organic functional groups on which Hg2t was effectively bound and turned off the fluorescence of the N-GQDs. The fluorescence of N-GQDs was turned on by the thiol functional group of thiourea that bound strongly with Hg2t and formed Hg2t/thiourea complexes. After constructing the sensor, the experimental conditions and parameters, such as the pH and Hg2t concentration, were investigated and optimized. Under the optimum conditions, the constructed fluorescence sensor showed high sensitivity to thiourea at concentrations from 0.5 to 14 mM with a low detection limit of 41.7 nM. The sensor also exhibited high specificity, excellent stability, and good reproducibility so that the determination of thiourea in various samples had acceptable values with good recoveries from 99% to 106%. The relative standard deviation was less than 4.1% (n ? 3).
关键词： thiourea,Fluorescence,nitrogen-doped graphene quantum dots (N-GQDs),Hg2t,sensor
更新于2025-11-14 17:04:02