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SELF-DECOMPOSITION EFFECT OF GRAPHENE BASED CdSe COMPOSITES FOR ORGANIC DYE IN DARK
摘要： Herein we obtain CdSe-TiO2 composite, graphene-CdSe composite and graphene-TiO2 composite by using a facile hydrothermal method. The as-prepared composites are characterized by Brunauer emmett Teller (BET) surface area measurement, X-ray diffraction (XRD), scanning electron microscopy (SEM) with an energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), UV-vis diffuse reflectance spectra (DRS). According to the decomposition results of methylene blue (MB) solution in dark, it can be observed that the graphene-CdSe composites show a very interesting character, self-decomposition effect of MB in dark.
关键词： CdSe,UV-vis DRS,Graphene,Hydrothermal,Self-decomposition
更新于2025-09-09 09:28:46
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Au/CdSe hybrid nanoflowers: a high photocurrent generating photoelectrochemical cells
摘要： Photoelectrochemical cell composed of solution-processed nanoflower heterostructure of Au core and eight CdSe petals was investigated for enhanced photocurrent generation. The electrode of CdSe nanorods displayed photocurrent density of 2.1 mA/cm2 whereas the Au core CdSe nanoflower exhibited 4.6 mA/cm2 corresponding to a 119% increase during photoelectrochemical cell performance. Both electrodes showed prompt response to the on/off cycles of light, the photocurrent gain (IPhoton/Idark) in CdSe nanorods is 124.7, while the value is 223.3 for Au/CdSe nanoflower, calculated from the growth-decay curves. Photoresponse time was dramatically improved for Au/CdSe nanoflower samples due to increasing in 66% incident photon-to-current emission. Electron lifetime of 21.63 and 48.71 ns was observed for the electrode of CdSe nanorods and Au/CdSe nanoflowers respectively. The prolonged electron lifetime in the case of the electrode of Au/CdSe nanoflowers was responsible for improving charge separation and as a consequence, higher photocurrent generation.
关键词： Au/CdSe,Heterostructure,Photoelectrochemical cells,Photocurrent,Nanoflower
更新于2025-09-09 09:28:46
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Accumulation of Solar Hydrogen in the Photoelectrochemical System Based on CdSe Photoanode and MH Cathode
摘要： The film photoanodes based on CdSe and NT-TiO2/CdSe have been formed by the electrochemical and painting methods. It is shown that the introduction of graphene oxide into the structure of the semiconductor CdSe film promotes absorption of light and leads to improvement in their characteristics by 25-30 %. The compatibility of the cathode based on composite of hydrogen-sorbing intermetallic alloys LaNi4.5Mn0.5 + LaNi3.5Al0.7Mn0.8 with current-conductive additives in pair with the CdSe photoanode is shown. It was found that 95 – 98 % of the total current generated under the influence of sunlight at the anodes was used on the formation and accumulation of hydrogen by cathodes.
关键词： photoelectrochemical system,photoanode,CdSe,solar hydrogen,MH cathode
更新于2025-09-09 09:28:46
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Fluorescent Metal-Semiconductor Hybrid Structures by Ultrasound-Assisted In-Situ Growth of Gold Nanoparticles on Silica-Coated CdSe-Dot/CdS-Rod Nanocrystals
摘要： Gold nanocrystals (AuNCs) were grown on the surface of silica coated CdSe-dot/CdS-rod core/shell nanocrystals by reduction of Au3+ ions in polyethylene glycol under ultrasonic irradiation. The polyethylene glycol not only prevents the penetration of gold ions or precursor molecules into the silica shell, but it also acts as the reducing agent for Au3+ ions. The silica shell’s surface promotes the heterogeneous nucleation of gold nanocrystals, while the ultrasonic irradiation accelerates and enhances the gold nucleation on the silica surface, and ensures the formation of AuNCs with a relatively narrow size distribution. The plasmon-exciton interaction in these metal-semiconductor hybrid systems leads to decreased fluorescence lifetimes and strongly reduced fluorescence blinking of individual hybrid structures.
关键词： ultrasonic irradiation,Gold nanocrystals,CdSe-dot/CdS-rod nanocrystals,plasmon-exciton interaction,polyethylene glycol
更新于2025-09-09 09:28:46
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Studies on Different Doped Zn Concentrations of CdSe Thin Films
摘要： Different Zn concentration was doped with CdSe thin films by Electron Beam Evaporation method. Crystallite variation was studied for doping effect and it was found to be about 40 to 50 nm respectively. Optical band gap values are found to be modified by doping as well as annealing. Annealed films showed considerable influence in their opto-elctronic and structural properties, which provided improvement in conversion efficiency of about 2.75% and 2.87% respectively.
关键词： PEC solar cells,Electron beam evaporation,Doping effect,XRD of CdSe
更新于2025-09-04 15:30:14
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Effect of Phosphine-Free Selenium Precursor Reactivity on The Optical and Vibrational properties of Colloidal CdSe Nanocrystals
摘要： Phosphine-free selenium precursor solutions have been prepared by heating at temperatures ranging from 160 °C to 240 °C and studied by means of infrared absorption spectroscopy. The colloidal CdSe nanocrystals (NCs) synthesized from all those solutions by the wet chemical method. The influence of heating temperature on the chemical reactivity of selenium precursor and its role on the optical and vibrational properties of CdSe NCs are discussed in details. Their morphology, particle size, structural, optical and vibrational properties were investigated using transmission electron microscopy, X-ray diffraction, UV-Vis, fluorescence and Raman spectroscopy, respectively.
关键词： vibrational properties,Phosphine-free selenium precursor,CdSe nanocrystals,optical properties
更新于2025-09-04 15:30:14
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High Visible Response of Vertical TiO2 Nanoclusters-CdSe Linked by Cysteine
摘要： Vertically oriented single-crystal TiO2 nanoclusters in tetramethylammonium hydroxide solution were synthesized hydrothermally directly on Ti substrate. N-Type semiconducting CdSe nanoparticles were then introduced deep coating TiO2 nanocrystalss via a two-step procedure using cystein as a surface coupling agent, followed by a subsequent electrodeposition process from selenosulfite to form orderly interconnecting heterojunctions. A key result achievement is that although the TiO2 nanocrystalss are less than 1 μm long, under the help of the bifunctional 2-amino-3-sulfhydrylpropanoic acid molecule linking the acceptor and donor materials, the virtue of strong visible absorption of single crystal TiO2 nanoclusters were fully developed in addition of ultraviolet, so that the heterojunction electrode exhibits excellent photoresponse in photoelectrochemical cells to visible lights, whose contribution is rather significant compared with that of ultraviolet lights. Vertical nanoclusters have advantages of leading electrons directly into the metal Ti substrate while maintaining the large surface area towards the electrolyte. These highly ordered nanohybrids are expected to have potential applications in photochemical solar cells with high efficiency.
关键词： TiO2 nanocluster,Visible lights,Sensitization,CdSe,Vertically oriented
更新于2025-09-04 15:30:14
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Giant Modal Gain Coefficients in Colloidal II-VI Nanoplatelets
摘要： Modal gain coefficient is a key figure of merit for a laser material. Previously, net modal gain coefficients larger than a few thousand cm-1 were achieved in II-VI and III-V semiconductor gain media, but this required operation at cryogenic temperatures. In this work, using pump-fluence-dependent variable-stripe-length measurements, we show that colloidal CdSe nanoplatelets enable giant modal gain coefficients at room temperature, up to 6,600 cm-1 under pulsed optical excitation. Furthermore, we show that exceptional gain performance is common to the family of CdSe nanoplatelets, as shown by examining samples having different vertical thicknesses and lateral areas. Overall, colloidal II-VI nanoplatelets with superior optical gain properties are promising for a broad range of applications, including high speed light amplification and loss compensation in plasmonic photonic circuits.
关键词： colloidal nanoplatelets,optical gain,variable stripe-length method,CdSe,modal gain coefficient,colloidal quantum wells
更新于2025-09-04 15:30:14
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Nonlinear absorption and Optical limiting of Ag–CdSe nano-hybrids of different growth times
摘要： Metal-semiconductor Nano-composites have enormous applications due to Plasmon –exciton coupling. Open aperture Z-scan is investigated for Ag–CdSe hybrid nanostructure, a toggle from saturable absorption process SA to reverse saturable absorption RSA is observed upon laser power increment. Proofs of crystal and morphological structure are given by selected area electron diffraction (SAED) and high resolution transmission electron microscope (HRTEM). Red shifting in photoluminescence spectra PL is observed which is ascribed to the particle size increment. Intriguing nonlinear findings can be used to engineer optical switching devices and optical limiters.
关键词： Photoluminescence,Open aperture Z scan,Ag:CdSe,Metal semiconductor nanohyrid structure,Optical limiting,Nonlinear absorption coefficient
更新于2025-09-04 15:30:14
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A TiO2/g-C3N4/CdS Nanocomposite-Based Photoelectrochemical Biosensor for Ultrasensitive Evaluation of T4 Polynucleotide Kinase Activity
摘要： Herein, an efficient photoelectrochemical (PEC) platform was constructed by a co-sensitization strategy with a cascade energy level arrangement for the ultrasensitive evaluation of T4 polynucleotide kinase (T4 PNK). Based on CdSe quantum dots (QDs) with an extremely narrow bandgap, this co-sensitization strategy offered a highly efficient sensitizer with a matching band-edge level of a ternary TiO2/g-C3N4/CdS nanocomposite. In this protocol, the ternary nanocomposite was first prepared to serve as the matrix to construct the PEC sensing platform. On the other hand, a well-designed hairpin DNA1 probe with 5’-hydroxyl termini was specifically phosphorylated by T4 PNK which would be selectively cleaved with lambda exonuclease (λ-Exo) outputting 3’-thiol end ssDNA2. After tagged with CdSe QDs, ssDNA2 was captured by the complementary capture DNA3 on the electrode surface. As a result, CdSe QDs were in close contact with the ternary nanocomposite matrix, leading to an enhanced photocurrent response. Therefore, this proposed PEC platform displayed an analytical performance with a wide linear range from 0.0001 to 0.02 U mL-1 and a low detection limit down to 6.9 × 10-5 U mL-1. Moreover, this ternary nanocomposite-based platform exhibited excellent selectivity, good reproducibility, and remarkable storage stability, which shows the great potential for the T4 PNK detection and inhibitor screening.
关键词： CdSe quantum dots,T4 polynucleotide kinase,ternary nanocomposite,co-sensitization strategy,photoelectrochemical biosensor
更新于2025-09-04 15:30:14