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Occurrence control of charged exciton for a single CdSe quantum dot at cryogenic temperatures on an optical nanofiber
摘要： We discuss photo-luminescence characteristics of CdSe core/shell quantum dots at cryogenic temperatures using a hybrid system of a single quantum dot and an optical nanofiber. The key point is to control the emission species of quantum dot to charged excitons, known as trions, which have superior characteristics to neutral excitons. We investigate the photocharging behavior for the quantum dots by varying the wavelength and intensity of irradiating laser light, and establish a method to create a permanently charged situation which lasts as long as the cryogenic temperature is maintained. The present photo-charging method may open a new route to applying the CdSe quantum dots in quantum photonics, and the hybrid system of photocharged quantum-dot and optical nanofiber may readily be applicable to a fiber-in-line single-photon generator.
关键词： Optical nanofiber,Cryogenic temperatures,CdSe quantum dots,Photocharging,Trions
更新于2025-09-23 15:21:01
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[IEEE 2019 4th Scientific International Conference Najaf (SICN) - Al-Najef, Iraq (2019.4.29-2019.4.30)] 2019 4th Scientific International Conference Najaf (SICN) - Study Evanescent-field Penetration Depth in Tapered Nano-fiber Optics
摘要： the use of etching in the fabrication of nanofiber optic (NFO) can enable the creation of thinner, longer, bundled, and strong wires. The aim of this etching methodology is to control the reduction of the core diameter and to demonstrate two different reducing methods applied to fabricate NFO. A large penetration depth of an evanescent field (EF) is the explanation of achievement for increasing a fiber-optic evanescent-field sensor (FOEFS). In general, the penetration depth (dp) of an optical fiber, stripped of its cladding, was a relation to the wavelength of the incident light, the refractive index (RI) of the surrounding medium and the incident angle on the basis of the ray-tracing model. Ray tracing analysis of tapered nano fiber optics segments and of combination taper probes make evident that the increases along the length of the taper, creating a segmented sensor with increased excitation light available at the surface for stimulating of ray transmitting. In this work, to study an NFO based on a tapered sensing probe by using the numerical analysis. The light power transmission and ultimate sensitivity of the element sensor are influenced by the incident angle, the numerical aperture (NA), core diameter, and taper ratio (TR). The TR of 0.1 and 0.7 are yield higher dp in certain regions. Then, the optimal result and the maximum dp were obtained with dp =1140 nm in TR=0.1 and a tapering length (L) of position tapering Z=40 mm.
关键词： fabricated nanofiber optics,ray tracing,tapered fiber optics,nanofiber optic sensors
更新于2025-09-23 15:19:57
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Graphene Quantum Dot Reinforced Electrospun Carbon Nanofiber Fabrics with High Surface Area for Ultra-High Rate Supercapacitors
摘要： High surface area, good conductivity, and high mechanical strength are important for carbon nanofiber fabrics (CNFs) as high-performance supercapacitor electrodes. However, it remains a big challenge because of the trade-off between the strong and continuous conductive network and well-developed porous structure. Herein, we report a simple strategy to integrate these properties into the electrospun CNFs by adding graphene quantum dots (GQDs). The uniformly embedded GQDs play a crucial bi-functional role in constructing entire reinforcing phase and conductive network. Compared with the pure CNF, the GQD-reinforced activated CNF exhibits a greatly enlarged surface area from 140 to 2032 m2 g-1 as well as significantly improved conductivity and strength of 5.5 and 2.5 times, respectively. The mechanism of robust reinforcing effect is deeply investigated. As freestanding supercapacitor electrode, the fabric performs high capacitance of 335 F g-1 at 1 A g-1 and extremely high capacitance retentions of 77% at 100 A g-1 and 45% at 500 A g-1. Importantly, the symmetric device can be charged to 80% capacitance within only 2.2 s, showing great potential for high-power startup supplies.
关键词： graphene quantum dot,carbon nanofiber,ultra-high rate,high surface area,supercapacitor
更新于2025-09-23 15:19:57
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Ionic conductivity enhancement of a??soggy sanda?? electrolytes with AlOOH nanofibers for dye-sensitized solar cells
摘要： As one of the main components, inorganic nanofillers have important effect on the performance of “soggy sand” electrolytes. In this study, we first incorporate AlOOH nanofibers into ionic liquid electrolytes to enhance the mechanical property and ionic conductivity of the electrolytes. The AlOOH nanofiber has high aspect ratio coupled with favorable surface properties such as rich hydroxyl groups, which facilitate to interact with cations of ionic liquids, promote salt dissociation, and form stable gels by self-assembly. In addition, the nanofiber fillers with high aspect ratio can form ion-conducting network channels and longer-range continuous ion transport pathways. The enhancing ionic conductivity of “soggy sand” electrolytes and performance of DSSCs due to addition of AlOOH nanofibers are systematically investigated by various techniques. The highest ionic conductivity of “soggy sand” electrolyte reaches 3.69 mS cm?1 at room temperature, which is 4 times than that of the pristine ionic liquid electrolyte. The effective solidification by AlOOH nanofibers provides substantial improvements in stability. The “soggy sand” electrolytes with AlOOH nanofibers can significantly improve the performance of devices by accelerating charge transport, reducing electron recombination and increasing charge collection efficiency. The DSSC with AlOOH nanofibers in electrolyte yields a high efficiency up to 7.89%, which is 29% higher than that of the reference device.
关键词： Nanofiber,Dye-sensitized solar cell,Ionic liquid,“Soggy sand” electrolyte,Ionic conductivity
更新于2025-09-23 15:19:57
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Effects of Electrospinning Solution Properties on Formation of Beads in Tio2 Fibers with PdO Particles
摘要： TiO2 fibers with catalytic PdO particles are of interest for use as porous catalytic converters to react NOx and CO to control air pollution. The fibers are first electrospun as template polymer fibers. The template polymer fibers are calcined to form the ceramic fibers. The electrospinning solution composition significantly affects fiber morphologies (beads) which in turn affect the catalyst performance. In this work, solutions containing Polyvinylpyrrolidone (PVP), Titanium (IV) Isopropoxide (TTIP), and Palladium (II) Chloride (PdCl2) were electrospun with the goal of fabricating beadless submicron composite fibers. The fibers were calcined to produce ceramic TiO2 submicron fibers with Palladium oxide (PdO) nanoparticles. To determine the solution recipes that form smooth PdO-TiO2 fibers without beads, fibers were electrospun and evaluated from solutions with varied mass concentrations of PVP and PdCl2 salt. The solution concentrations indirectly influenced the electrospinning performance through solution viscosity, surface tension and electrical conductivity. The ceramic fibers were produced with average diameters in the range of 180-280 nm and with minimal formation of beads when the solution had viscosity in the range of 52 to 80 cP and conductivity in the range of 45-67 μs/cm. It was found that the surface tension of the solutions did not vary significantly and did not strongly affect the formation of beads.
关键词： nanofiber,beads,Electrospinning,catalyst support,ceramic
更新于2025-09-19 17:15:36
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Janus nanofiber array pellicle: facile conjugate electrospinning construction, structure and bifunctionality of enhanced green fluorescence and adjustable magnetism
摘要： A [Fe3O4/polyvinyl pyrrolidone (PVP)]//[Tb(BA)3phen/PVP] Janus nanofiber array pellicle (denoted JNAP) was successfully constructed by facile conjugate electrospinning without twisting for the first time. The JNAP offers the dual-functionality of fluorescence and magnetism. This technology entirely solves the dilemma of the magnetic spinning dope and fluorescent spinning dope being easily mixed together during the parallel electrospinning process, as it achieves complete segregation of magnetic nanoparticles and fluorescent molecules. Moreover, conjugate electrospinning without twisting has fewer requirements on the viscosity of the spinning dope compared with parallel electrospinning, in which the two spinning dopes should have the same viscosity. It was satisfactorily found that the JNAP has higher fluorescence intensity than the corresponding non-aligned Janus nanofiber pellicle. The magnetism of the JNAP could be tailored by changing the doping amount of the Fe3O4 NPs. The JNAP has potential applications in nanotechnology and biomedicine, etc., due to its enhanced green fluorescence and adjustable magnetism. In addition, this design concept and manufacturing process provide a facile way for preparing other one-dimensional Janus nanomaterials with multifunctionality.
关键词： magnetism,bifunctionality,conjugate electrospinning,fluorescence,Janus nanofiber
更新于2025-09-19 17:15:36
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Cellulose nanofiber nanocomposites with aligned silver nanoparticles
摘要： Celluloses have attracted much attention as sustainable and abundant materials. Herein, we focus on nanocomposites based on the oxidation-treated nano-sized fibrillated celluloses, namely TOCNs. The silver nanoparticles (AgNPs) were prepared in TOCN aqueous dispersion. Generally, the AgNPs are quickly agglomerated after preparation. For the inhibition of the agglomeration of AgNPs, it is required that AgNPs were prepared under the chelation of TOCN, followed by reduction therein. Therefore, AgNPs possessed the nano-scaled radii and aligned along the TOCN from the atomic force microscopic measurements. The thermal stabilities and mechanical properties were increased. The anisotropic thermal conductivities originated from the orientation of TOCN in nanocomposites were observed. The loading of the large amounts of AgNP fillers led to the drastic increase of the thermal and electrical conductivities. The conductive paths of heat and electron were formed by the contact of AgNP with each other. We functionalized the TOCN papers through the loading of AgNPs and the obtained nanocomposites sheets served as conductors.
关键词： Cellulose nanofiber,mechanical property,TEMPO-mediated oxidation,silver nanoparticle,thermal conductivity
更新于2025-09-19 17:15:36
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Optimized Polyvinylidene Fluoride Nanofiber Webs for Flexible Energy Harvesters
摘要： This work reports the process optimization of various electrospinning parameters to fabricate polyvinylidene fluoride based piezoelectric flexible nanofiber webs for passive sensing and energy harvesting applications. Process parameters like electrospinning voltage and drum speed have been taken into consideration while optimizing the electrospun nanofiber webs for maximizing their piezoelectric property. Finally, the optimized recipe is used to fabricate a flexible PVDF nanofiber energy harvester to demonstrate the energy harvesting capability of such nanofiber webs.
关键词： nanofiber,electrospinning,polyvinylidene fluoride (PVDF),piezoelectricity,sensor
更新于2025-09-19 17:15:36
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Smart Golden Leaves Fabricated by Integrating Au Nanoparticles and Cellulose Nanofibers
摘要： A simple processing technology based on spontaneous arrangement of gold nanoparticles (AuNPs) on cellulose nanofibers (CNFs) makes it possible to form a gold leaf with superior mechanical, chemical and electrical characteristics with a small amount of gold (< 15 vol.%). The electrical resistivity of the AuNP/CNF hybrid film reached 8.7 × 10?? Ω cm at 13 vol.% corresponding to that of a gold plate (2.9 × 10?? Ω cm) through a distribution of AuNP inside the film in the form of a band. The AuNPs work not only as linkers between various CNFs in the hybrid structure but also as scaffolds. Self-assembly allows the formation of leaves on three-dimensional micrometer-sized substrates, on which it is impossible to form a uniform flexible metallic layer using conventional techniques such as sputtering, vapor deposition, and electroless plating. The hybrid film holds great promise as a novel gold leaf for a wide range of applications, including coatings, smart papers, electronic skins, and wearable devices owing to its unique combination of superior properties, as well as good productivity, processability, and renewability.
关键词： cellulose nanofiber,organic/inorganic hybrid film,self-healing,spontaneous binding,gold nanoparticle
更新于2025-09-19 17:15:36
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Trace level toxic ammonia gas sensing of single-walled carbon nanotubes wrapped polyaniline nanofibers
摘要： This paper presents a two-step enhancement and a comprehensive analysis of single-walled carbon nanotubes (SWCNTs) wrapped polyaniline nanofiber (NPANI) ammonia (NH3) gas sensor at room temperature. SWCNT-PANI composites are successfully synthesized using an efficient and cost-effective rapid in situ chemical polymerization method. The structural morphology and modification of the samples are characterized using field-emission scanning electron microscopy and HRTEM. FTIR and Raman spectroscopic studies are also performed to gain a better insight into the chemical environmental interaction in the as-prepared nanocomposite. The analysis confirms the successful formation of the nanocomposite. The observed NH3 gas-sensing response at 10 ppm of SWCNT, f-SWCNT (functionalised SWCNT), and SWCNT-PANI composite sensors are 5%–6%, 18%–20%, and 24%–25%, respectively. The SWCNT-PANI composite sensors have shown higher repeatability, selectivity, long-term stability, and fast response-recovery characteristics as compared to f-SWCNTs and pristine SWCNT sensors. Concentration and temperature dependent gas-sensing studies are also analyzed. The sensor response also shows a linear relationship with NH3 gas concentration and an inverse relationship with increasing temperature.
关键词： Raman spectroscopy,rapid in situ chemical polymerization,ammonia gas sensor,polyaniline nanofiber,field-emission scanning electron microscopy,FTIR,HRTEM,room temperature,single-walled carbon nanotubes
更新于2025-09-19 17:13:59