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The Self-Assembly of Cu-In-S Quantum Dots with Aggregation-Induced Emission into 3D Network Triggered by Cation and Its Application as A Novel Metal-Enhanced Fluorescent Nanosensor for Detecting Zn (Ⅱ)
摘要： A novel self-assembly phenomenon triggered by Zn2+ of Cu-In-S quantum dots with aggregation-induced emission effect was presented in this paper. Hydrophilic Cu-In-S quantum dots with aggregation-induced emission effect were successfully prepared. They were monodisperse spherical nanoparticles with the diameter of 2.8 ± 0.4 nm and had weak fluorescence in aqueous solution. However, the solution emitted strong fluorescence after addition of Zn2+. The results of TEM and SEM indicated the monodisperse quantum dots self-assembled into 3D networks of Cu-In-S quantum dots-Zn2+, which hindered the motion of quantum dots. Besides, the Zn2+ in the mixture passivated the surface defects. The phenomenon also proved by florescence lifetime and XPS. Thus the radiation decay decreased and followed by strong fluorescent emission. Interestingly, the degree of aggregation was proportional to the amount of Zn2+ and the fluorescent intensity. Based on this interesting phenomenon, a novel metal enhanced fluorescent nanosensor for detecting Zn2+ was established. The results demonstrated the proposed method had a good selectivity and linearity in the concentration range of 0-800 nmol?L-1 with a limit of detection of 1.99 ppb. These results showed a promising future in the field of metal-enhanced fluorescent probes of the Cu-In-S quantum dots.
关键词： Surface defects,Metal-enhanced sensor,Quantum dots,Restriction of motion,Aggregation-induced emission
更新于2025-11-14 15:23:50
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Preparation of DNA functional phosphorescent quantum dots and application in melamine detection in milk
摘要： Bio-functionalization of quantum dots (QDs) is of important value in practical applications. With single-stranded DNA (ssDNA) rich in thymine T and thioguanine G taken as the template, a new-type nanocomposite material (ssDNA-PQDs) synthesized from low-toxicity T-ssDNA functionalized Mn–ZnS and room-temperature phosphorescent (RTP) QDs (PQDs) was prepared in this paper by optimizing synthesis conditions, and these ssDNA-PQDs could emit orange RTP signals at 590 nm. As these ssDNA-PQDs are rich in T sequences and T sequences can bond with melamine through the hydrogen-bond interaction, ssDNA-PQDs experience aggregation, thus causing phosphorescent exciton energy transfer (PEET) between ssDNA-PQDs of di?erent particle sizes and their RTP quenching. Based on this principle, an RTP detection method for melamine was established. The linear range and detection limit of the detection method are 0.005–6 mM and 0.0016 mM respectively. As this method is based on the RTP nature of ssDNA-PQDs, it can avoid disturbance from background ?uorescence and scattered light of the biological ?uid, and it is very suitable for melamine detection in the biological ?uid milk.
关键词： DNA functionalized quantum dots,milk safety,melamine detection,room-temperature phosphorescent
更新于2025-11-14 15:23:50
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Full color carbon dots through surface engineering for constructing white light-emitting diodes
摘要： White light-emitting diodes (WLEDs) devices are replacing the filament lamp and they can provide a light close to the natural sunlight, which have thus drawn considerable attention in these recent years. It remains a scientific challenge to develop WLEDs using environmentally friendly, easy-to-process and cost-effective phosphors. Here we synthesized blue-, green- and red-carbon dots (denoted as B-, G- and R-CDs) by a facile solvothermal method with high dispersity both in aqueous and organic solvent. The quantum yield (QY) of the R-CDs achieved up to 24.7%. These CDs can be easily dissolved in polyvinylpyrrolidone (PVP) colloid, leading to the production of ultraviolet (UV)-excited LED devices to avoid the retinal damage caused by blue ray excitation. The fluorescence emission of the WLED has a wide band, covering the whole visible light region. Importantly, the influence of doping that gives rise to the change of emissive colors has been elucidated by X-ray photoelectron spectroscopy (XPS) combined with a computation method in order to provide a systematic controllable tuning on the functionalization of CDs. As such, WLEDs were demonstrated with color coordinates of (0.33, 0.33), a color temperature of 5612 K in the CIE chromaticity diagram with good anti-photobleaching and a color rendering index (CRI) of 89.
关键词： polyvinylpyrrolidone,White light-emitting diodes,solvothermal method,UV-excited LED devices,density functional theory,quantum yield,X-ray photoelectron spectroscopy,carbon dots
更新于2025-11-14 15:18:02
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Tannic acid-derivatized graphitic carbon nitride quantum dots as an “on-off-on” fluorescent nanoprobe for ascorbic acid via copper(II) mediation
摘要： A microwave-assisted hydrothermal route was employed to prepare fluorescent tannic acid (TA)-derivatized graphitic carbon nitride quantum dots. The resulting dots display blue fluorescence (best measured at excitation/emission wavelengths of 350/452 nm) with a quantum yield as high as ~44%. The incorporated TA imparts a fluorescence switching behavior in that very low concentrations of Cu(II) can quench the fluorescence, while (AA) can restore it. It is presumed that AA causes Cu(II) to be transformed to Cu(I). Based on these findings, a fluorometric method was designed for AA detection. The probe allows AA to be detected with a 50 pM limit of detection and a linear analytical range that extends from 0.1 to 200 nM of AA. Real and spiked samples were successfully assayed by the probe to demonstrate its analytical applicability.
关键词： Fluorescence recovery,Metal ions,Graphitic nanosheets,Biomolecules,Polyphenolic compounds,Optical probe,Quantum dots
更新于2025-10-22 19:40:53
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Gold doping induced strong enhancement of carbon quantum dots fluorescence and oxygen evolution reaction catalytic activity of amorphous cobalt hydroxide
摘要： Gold doping induced strong enhancement of carbon quantum dots fluorescence and oxygen evolution reaction catalytic activity of amorphous cobalt hydroxide. Water splitting using electrocatalysts is expected to provide an alternative green energy source to meet increasing energy demands as well as addressing environmental concerns related to fossil fuels. Herein, we report one-step synthesis of sulfur, nitrogen and Au-doped carbon quantum dots (Au-SCQDs) and strong enhancement of fluorescence intensity and oxygen evolution reaction (OER) catalytic activity of amorphous Co(OH)2 nanoparticles compared to pure Co(OH)2 as well as commercial RuO2 and Pt/C catalysts. Au doping into sulfur and nitrogen co-doped CQDs showed over seventy times enhanced fluorescence. OER studies of amorphous-Co(OH)2 incorporated Au-SCQDs produced current density of 178 mA cm?2 at the applied potential of 2.07 V whereas un-doped Co(OH)2 showed current density of 59 mA cm?2. To produce geometric current density of 10 mA cm?2, amorphous Co(OH)2-Au-SCQDs (CSA) required 388–456 mV overpotential depending on the Au ion concentration used for preparing the Au-SCQDs, which is equal to or lower than overpotential required by commercial electrocatalysts. The strongly enhanced OER activity of Co(OH)2-Au-SCQDs (CSA) was attributed to the presence of electronegative metallic conducting Au atoms along with the high catalytic surface area of amorphous Co(OH)2. The present studies demonstrate a new method of exploiting amorphous Co(OH)2NPs electrocatalysts that could provide more catalytically active sites by integrating an electronegative conducting Au atom doped SCQDs matrix.
关键词： amorphous cobalt hydroxide,fluorescence,water splitting,Gold doping,carbon quantum dots,oxygen evolution reaction,electrocatalysts
更新于2025-10-22 19:40:53
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Enhanced Photoluminescence in Quantum Dots–Porous Polymer Hybrid Films Fabricated by Microcellular Foaming
摘要： The color conversion efficiency of thin polymeric layers embedding quantum dots (QDs) is limited by their negligible light scattering ability and by the insufficient absorption of the excitation photons. In this study, a route is presented to tackle these optical shortcomings by introducing a tailored network of micropores inside these hybrid films. This is achieved by exploiting the microcellular foaming approach which is rapid, cost effective and only makes use of a green solvent (supercritical carbon dioxide). With an appropriate combination of the applied pressure and temperature during foaming, and by using a proper film thickness, the photoluminescence (PL) intensity is enhanced by a factor of up to 6.6 compared to an equivalent but unfoamed hybrid film made of CdSe/ZnS QDs in a polymethyl methacrylate matrix. Spectroscopic measurements and ray tracing simulations reveal how the porous network assists UV/blue light absorption by the QDs and the subsequent outcoupling of the converted light. The approach improves the PL for various QD concentrations and can be easily scaled up and extended to other polymeric matrices as well as light converting materials.
关键词： quantum dots,microcellular foaming,porous polymers,photoluminescence,ray tracing simulations
更新于2025-10-22 19:40:53
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Enhancing light absorption by colloidal metal chalcogenide quantum dots <i>via</i> chalcogenol(ate) surface ligands
摘要： Chemical species at the surface (ligands) of colloidal inorganic semiconductor nanocrystals (QDs) markedly impact the optoelectronic properties of the resulting systems. Here, post-synthesis surface chemistry modification of colloidal metal chalcogenide QDs is demonstrated to induce both broadband absorption enhancement and band gap reduction. A comprehensive library of chalcogenol(ate) ligands is exploited to infer the role of surface chemistry on the QD optical absorption: the ligand chalcogenol(ate) binding group mainly determines the narrowing of the optical band gap, which is attributed to the np occupied orbital contribution to the valence band edge, and mediates the absorption enhancement, which is related to the π-conjugation of the ligand pendant moiety, with further contribution from electron donor substituents. These findings point to a description of colloidal QDs that may conceive ligands as part of the overall QD electronic structure, beyond models derived from analogies with core/shell heterostructures, which consider ligands as mere perturbation to the core properties. The enhanced light absorption achieved via surface chemistry modification may be exploited for QD-based applications in which an efficient light-harvesting initiates charge carrier separation or redox processes.
关键词： colloidal metal chalcogenide quantum dots,light absorption,optoelectronic properties,surface ligands,band gap reduction
更新于2025-10-22 19:40:53
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Surface Plasmon Resonance Enhancement of PbS Quantum Dot-Sensitized Solar Cells
摘要： Lead sulfide (PbS)-sensitized quantum dot solar cells (QDSC) were fabricated using TiO2 and TiO2–Au plasmonic nanocomposite films by successive ionic layer adsorption and reaction (SILAR) method. The average size of gold nanoparticles (GNPs) used for fabricating nanocomposite films was ~ 15 nm. Thin plasmonic QDSC, with a film thickness of 10 μm, showed an increase of ~ 11% in photocurrent and ~ 6% in overall energy conversion efficiency compared to the device without GNPs. The improved performance of QDSCs is attributed to the increased absorption due to the plasmonic near-field effects of the incorporated GNPs. High-efficiency PbS/CdS-co-sensitized thick cells with 16 μm bilayer TiO2 also showed improvement in photocurrent and efficiency. The results show that the plasmonic-enhanced absorption can be used to augment efficiency of QDSC devices in much the same fashion as that of dye-sensitized solar cells.
关键词： Gold nanoparticles,Quantum dot-sensitized solar cells,Plasmonics,Photovoltaics
更新于2025-10-22 19:40:53
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Oxygen Plasma-Induced p-type Doping Improves Performance and Stability of PbS Quantum Dot Solar Cells
摘要： PbS quantum dots (QDs) have been extensively studied for photovoltaic applications thanks to their facile and low-cost fabrication processing and interesting physical properties such as size-dependent and tunable bandgap. However, the performance of PbS QDs based solar cells is highly sensitive to the humidity level in the ambient air, which is a serious obstacle toward its practical applications. Although it has been previously revealed that oxygen doping of the hole transporting layer (HTL) can mitigate the cause of this issue, the suggested methods to recover the device performance are time-consuming and relatively costly. Here, we report on a low-power oxygen plasma treatment as a rapid and cost-effective method to effectively recover the device performance and stability. Our optimization results show that a 10 min treatment is the best condition, resulting in an enhanced power conversion efficiency (PCE) from 6.9% for the as-prepared device to 9% for the plasma treated one. Moreover, our modified device shows long-term shelf-life stability.
关键词： colloidal quantum dots,plasma,lead sulfide,photovoltaics,stability
更新于2025-10-22 19:40:53
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Zinc ions modified InP quantum dots for enhanced photocatalytic hydrogen evolution from hydrogen sulfide
摘要： Through direct addition of inorganic zinc ions into the solution of indium phosphide quantum dots (InP QDs) at ambient environment, we here present a facile but effective method to modify InP QDs for photocatalytic hydrogen evolution from hydrogen sulfide (H2S). X-ray diffraction patterns and transmission electron microscopic images demonstrate that zinc ions have no significant influence on the crystal structure and morphology of InP QDs, while X-ray photoemission spectra and UV–Vis diffuse and reflectance spectra indicate that zinc ions mainly adsorbed on the surface of InP QDs. Photocatalytic results show the average hydrogen evolution rate has been enhanced to 2.9 times after modification and H2S has indeed involves in the hydrogen evolution process. Steady-state and transient photoluminescence spectra prove that zinc ions could effectively eliminate the surface traps on InP QDs, which is crucial to suppress the recombination of charge carriers. In addition, the electrostatic interaction between zinc ions and the surface sulfide from InP QDs could mitigate the repulsion between QDs and sulfide/hydrosulfide, which may promote the surface oxidative reaction during photocatalysis. This work avoids the traditional harsh and complicated operations required for surface passivation of QDs, which offers a convenient way for optimization of QDs in photocatalysis.
关键词： Hydrogen sulfide,Photocatalytic hydrogen evolution,InP quantum dots,Surface modification
更新于2025-10-22 19:38:57