scholarly journals Preparation and Performance of Radiata-Pine-Derived Polyvinyl Alcohol/Carbon Quantum Dots Fluorescent Films

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 67 ◽  
Author(s):  
Li Xu ◽  
Yushu Zhang ◽  
Haiqing Pan ◽  
Nan Xu ◽  
Changtong Mei ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Water Resistance ◽  
Cellulose Nanofibers ◽  
Tensile Modulus ◽  
Radiata Pine ◽  
Carbon Quantum Dots ◽  
Nanocomposite Films ◽  
Excitation Wavelength ◽  
Nano Materials ◽  
Nano Composite

In this study, the low-cost processing residue of Radiata pine (Pinus radiata D. Don) was used as the lone carbon source for synthesis of CQDs (Carbon quantum dots) with a QY (The quantum yield of the CQDs) of 1.60%. The CQDs were obtained by the hydrothermal method, and +a PVA-based biofilm was prepared by the fluidized drying method. The effects of CQDs and CNF (cellulose nanofibers) content on the morphology, optical, mechanical, water-resistance, and wettability properties of the PVA/CQDs and PVA/CNF/CQDs films are discussed. The results revealed that, when the excitation wavelength was increased from 340 to 390 nm, the emission peak became slightly red-shifted, which was induced by the condensation between CQDs and PVA. The PVA composite films showed an increase in fluorescence intensity with the addition of the CNF and CQDs to polymers. The chemical structure of prepared films was determined by the FTIR spectroscopy, and no new chemical bonds were formed. In addition, the UV transmittance was inversely proportional to the change of CQDs content, which indicated that CQDs improved the UV barrier properties of the films. Furthermore, embedding CQDs Nano-materials and CNF into the PVA matrix improved the mechanical behavior of the Nano-composite. Tensile modulus and strength at break increased significantly with increasing the concentration of CQDs Nano-materials inside the Nano-composite, which was due to the increased in the density of crosslinking behavior. With the increase of CQDs content (>1 mL), the water absorption and surface contact angle of the prepared films decreased gradually, and the water-resistance and surface wettability of the films were improved. Therefore, PVA/CNF/CQDs bio-nanocomposite films could be used to prepare anti-counterfeiting, high-transparency, and ultraviolet-resistant composites, which have potential applications in ecological packaging materials.

scholarly journals Preparation and Properties of Cyanobacteria-Based Carbon Quantum Dots/Polyvinyl Alcohol/ Nanocellulose Composite

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1143 ◽  
Author(s):  
Li Xu ◽  
Ying Li ◽  
Shiyu Gao ◽  
Yue Niu ◽  
Huaxuan Liu ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Polyvinyl Alcohol ◽  
Water Resistance ◽  
Composite Films ◽  
Barrier Properties ◽  
Carbon Quantum Dots ◽  
Infrared Light ◽  
Quantum Yields ◽  
Hydroxyl Groups ◽  
Light Barrier

Blue luminescent carbon quantum dots (CQDs) were prepared from cyanobacteria by a hydrothermal method. The PL quantum yields of the obtained CQDs was 5.30%. Cyanobacteria-based carbon quantum dots/polyvinyl alcohol/nanocellulose composite films were prepared, which could emit bright blue under UV light. FTIR characterization showed that the composite films had hydroxyl groups on the surface and no new groups were formed after combining the three materials. The photoluminescence (PL) spectra revealed that the emission of the prepared CQDs was excitation dependent. Studies on the water resistance performance and light barrier properties of the composite films showed that they possessed higher water resistance properties and better UV/infrared light barrier properties. Therefore, we report the cyanobacteria-based carbon quantum dots/polyvinyl alcohol/nanocellulose composite films have the potential to be applied in flexible packaging materials, anti-fake materials, UV/infrared light barrier materials and so on.

Preparation and Luminescence Properties of the Nano- Composite Materials LaF3 - SiO2: Eu3+

2011 ◽  
Vol 335-336 ◽  
pp. 981-984
Author(s):  
Xi Gui Wang ◽  
Xiao Xian Wang
Keyword(s):  
Room Temperature ◽  
Annealing Temperature ◽  
Sol Gel ◽  
Excitation Wavelength ◽  
Nano Materials ◽  
Nano Composite ◽  
Optimal Doping ◽  
Cerium Fluoride ◽  
Mineral Structure ◽  
Optimum Annealing Temperature

Eu3+doped LaF3-SiO2nano-composite material were synthesized by sol-gel method at room temperature, and the structure and properties were characterized by XRD, TG-DTA, IR, excitation and emission spectrum. The structure indicated that the optimal doping formula for preparing nano-materials was La5Si95that transformed into a stable mineral structure of cerium fluoride, and mainly found Si-O-Si bonds when the temperature was above 500 °C. Luminous property researches showed that the optimum annealing temperature was 500 °C. The best excitation wavelength was 395 nm when the monitoring wavelength was 612 nm, and the optimal doping molar concentration of Eu3+was 0.35 mol %.

scholarly journals Facile and High-yield Synthesis of N-doped Carbon Quantum Dots from Biomass Quinoa Saponin for the Detection of Co2+

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Cuo Zhou ◽  
Shunwei Wu ◽  
Shenghui Qi ◽  
Weijun Song ◽  
Chunyan Sun
Keyword(s):  
Quantum Dots ◽  
Metal Ion ◽  
Light Emission ◽  
Low Cost ◽  
Carbon Quantum Dots ◽  
High Yield ◽  
Excitation Wavelength ◽  
Uniform Size ◽  
Orthogonal Experiments ◽  
Co2 Detection

Hydrothermal synthesis of carbon quantum dots (CQDs) from natural biomass is a green and sustainable route for CQDs applications in various fields. In this work, the preparation and characterization of CQDs based on quinoa saponin were investigated. The optimum synthetic conditions determined by orthogonal experiments were as follows: 2 g quinoa saponin powder and 0.04 mol ethylenediamine reacted at 200°C for 10 h. The relative fluorescence quantum yield (QY = 22.2%) can be obtained, which is higher than some results reported in the literatures. The prepared CQDs had a small and uniform size (∼2.25 nm) and exhibited excitation wavelength-dependent blue light emission behavior. The CQDs displayed excellent sensitivity for Co2+ detection along with good linear correlation ranging from 20 to 150 µM and the detection limit of 0.49 µM. The CQDs prepared in this experiment were successfully implanted into soybean sprouts for fluorescence imaging. The sprouts could grow healthily even soaked in the CQDs solution for two weeks, demonstrating the low toxicity of the CQDs. The advantages of the CQDs, such as low cost, ease of manufacture, nontoxicity, and stability, have potential applications in many areas such as metal ion detection and biosensing.

scholarly journals Carbon Quantum Dots for Biomedical Applications: Review and Analysis

2021 ◽  
Vol 8 ◽  
Author(s):  
Nayab Azam ◽  
Murtaza Najabat Ali ◽  
Tooba Javaid Khan
Keyword(s):  
Quantum Dots ◽  
Biomedical Applications ◽  
Near Infrared ◽  
Pharmaceutical Formulations ◽  
Carbon Quantum Dots ◽  
Excitation Wavelength ◽  
Physiochemical Properties ◽  
Electrochemical Biosensing ◽  
New Type ◽  
Low Toxicity

Carbon quantum dots (CQDs) are a new type of nano-carbons that are currently favored over semiconductor quantum dots (QDs) because of their solubility, low toxicity, eco-friendliness, and cheap and facile synthesis giving desired optical characteristics. Moreover, their physiochemical properties can be controlled by their synthetic route. CQDs can emit fluorescence in the range from the UV to the near-infrared (NIR) region, making them suitable for biomedical applications. Fluorescence in these nano-carbon atoms can be tuned by varying the excitation wavelength. As of now, CQDs have been used in various applications such as in bioimaging, biosensing, electrochemical biosensing, drug delivery, gene delivery, photodynamic therapy in the treatment of cancers, pharmaceutical formulations, and treating inflammation. This article highlights the current progress and advancement of CQDs with focus on their synthetic routes, chemical and optical properties, and biomedical applications along with new perceptions in this interesting and promising field.

scholarly journals Facile Synthesis of Nitrogen-Doped Carbon Quantum Dots with Chitosan for Fluorescent Detection of Fe3+

Polymers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1731 ◽  
Author(s):  
Zhao ◽  
Wang ◽  
Zhao ◽  
Deng ◽  
Xia
Keyword(s):  
Quantum Dots ◽  
Fluorescent Sensor ◽  
Nitrogen Sources ◽  
Carbon Quantum Dots ◽  
Fluorescent Detection ◽  
Excitation Wavelength ◽  
Environmental Application ◽  
Quenching Effect ◽  
Nitrogen Doped ◽  
Nitrogen Doped Carbon

A facile, economical, and one-step hydrothermal method was used to prepare highly luminescent nitrogen-doped carbon quantum dots (N-CQDs) with chitosan as both carbon and nitrogen sources. The as-prepared N-CQDs have an average size of 2 nm and exhibit excitation wavelength-dependent fluorescence with a maximum excitation and emission at 330 and 410 nm, respectively. Furthermore, due to the effective quenching effect of Fe3+ ions, the prepared N-CQDs can be used as a fluorescent sensor for Fe3+ ion-sensitive detection with a detection limit of 0.15 μM. The selectivity experiments revealed that the fluorescent sensor is specific to Fe3+ even with interference by high concentrations of other metal ions. Most importantly, the N-CQD-based Fe3+ ion sensor can be successfully applied to the determination of Fe3+ in real water samples. With excellent sensitivity and selectivity, such stable and cheap carbon materials are potentially suitable for the monitoring of Fe3+ in environmental application.

Characteristic Excitation Wavelength Dependence of Fluorescence Emissions in Carbon “Quantum” Dots

2017 ◽  
Vol 121 (50) ◽  
pp. 28180-28186 ◽  
Author(s):  
Gregory E. LeCroy ◽  
Fabrizio Messina ◽  
Alice Sciortino ◽  
Christopher E. Bunker ◽  
Ping Wang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Wavelength Dependence ◽  
Carbon Quantum Dots ◽  
Excitation Wavelength ◽  
Excitation Wavelength Dependence

scholarly journals The Role of Carbon Quantum Dots in Organic Photovoltaics: A Short Overview

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 232
Author(s):  
Barbara Vercelli
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Solar Cells ◽  
Organic Solar Cells ◽  
Structural Engineering ◽  
Energy Levels ◽  
Dye Sensitized Solar Cells ◽  
Carbon Quantum Dots ◽  
Excitation Wavelength ◽  
Photovoltaic Devices

Carbon quantum dots (CDs) are a new class of fluorescent carbonaceous nanomaterials that were casually discovered in 2004. Since then, they have become object of great interest in the scientific community because of their peculiar optical properties (e.g., size-dependent and excitation wavelength-dependent fluorescence), which make them very similar to the well-known semiconductor quantum dots and suitable for application in photovoltaic devices (PVs). In fact, with appropriate structural engineering, it is possible to modulate CDs photoluminescence properties, band gap, and energy levels in order to realize the band matching suitable to enable the desired directional flow of charge carriers within the PV device architecture in which they are implanted. Considering the latest developments, in the present short review, the employment of CDs in organic photovoltaic devices (OPVs) will be summarized, in order to study the role played by these nanomaterials in the improvement of the performances of the devices. After a first brief summary of the strategies of structural engineering of CDs and the effects on their optical properties, the attention will be devoted to the recent highlights of CDs application in organic solar cells (OSCs) and in dye sensitized solar cells (DSSCs), in order to guide the users towards the full exploitation of the use of these nanomaterials in such OPV devices.

scholarly journals Flexible sodium-ion batteries using electrodes from Samanea saman tree leaf-derived carbon quantum dots decorated with SnO2 and NaVO3

Clean Energy ◽  
2021 ◽  
Vol 5 (2) ◽  
pp. 354-374
Author(s):  
Baskar Thangaraj ◽  
Surawut Chuangchote ◽  
Nutthapon Wongyao ◽  
Pravin Raj Solomon ◽  
Kamonchanok Roongraung ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Quantum Yield ◽  
Discharge Capacity ◽  
Carbon Quantum Dots ◽  
Sodium Ion ◽  
Excitation Wavelength ◽  
Sodium Ion Batteries ◽  
Specific Discharge ◽  
Samanea Saman ◽  
Discharge Capacities

Abstract Carbonaceous materials with large interlayer spacing and disordered structure are considered suitable as electrodes in sodium-ion batteries so as to overcome the problem encountered in conventional electrodes. In this study, carbon quantum dots (CQDs) decorated with SnO2 and NaVO3 are used as electrodes in the fabrication of flexible Na-ion batteries. CQDs are prepared from dead leaves of the Samanea saman tree through alkaline-peroxide treatment and hydrothermal carbonization. As-prepared CQDs exhibit a quantum yield of 21.03% at an excitation wavelength of 360 nm. Various separators such as indium-doped tin oxide/polyoxyethylene tridecyl ether (ITO/PTE), rice paper (RP), silicone with three big holes (SIL BH), silicone with many small holes (SIL SH) and cellulose paper (CP) have been tried in flexible Na-ion batteries. SIL SH achieved higher specific capacitance (881 F g–1) than other separators due to the function of many small holes on the surface of the silicone. The SIL SH separator delivered higher discharge capacities of 141 and 114 mC g–1 at 1.5 and 2.5 V than SIL BH. The RP separator delivered specific discharge capacities of 1087 and 347 mC g–1 in the 1st and 50th cycles, respectively, at 1 V. The RP separator delivered a high initial specific discharge capacity of 698 mC g–1 at 2 V and maintained a good discharge capacity of 222 mC g–1 in the 50th cycle. As compared to RP, SIL SH delivered high specific discharge capacity of 4246 in 1st cycle at 2 V but maintained a capacity of 71 mC g–1 in the 50th cycle. This study reveals the scope of developing flexible Na-ion batteries with high capacity and cyclability using carbonaceous materials derived from the leaves of the S. saman tree. Carbon quantum dots (CQDs)-decorated with SnO2 and NaVO3 are used as electrodes in the fabrication of flexible Na-ion batteries. CQDs exhibit a quantum yield of 21% at the excitation wavelength of 360 nm. The electrochemical performances of fabricated batteries are investigated by cyclic voltammetry.

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