Synthesis of Photoluminescent Core–Shell-Structured Carbon dots@silica Nanocomposite Fingermark Powders for Latent Fingermarks Visualization

NANO ◽  
2019 ◽  
Vol 14 (06) ◽  
pp. 1950068
Author(s):  
Hong Yu Chen ◽  
Li Liu
Keyword(s):  
Carbon Dots ◽  
Uv Light ◽  
Sol Gel ◽  
Fluorescent Label ◽  
Core Shell ◽  
X Ray Diffraction ◽  
Visible Absorption ◽  
Transmission Electron ◽  
Reduced Iron Powder ◽  
Latent Fingermark

To obtain solid-state photoluminescent core–shell-structured carbon dots@silica (C-dots@SiO2) nanocomposites, the C-dots were synthesized by microwave irradiation and were dispersed in SiO2through sol–gel technique. Then, the excellent fluorescent property with excitation-independent feature and the core–shell structure of C-dots@SiO2nanocomposites were successfully characterized through the fluorescence spectroscopy, ultraviolet–visible absorption spectroscopy (UV-Vis), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The as-prepared C-dots@SiO2powder was mixed with reduced iron powder and then applied to latent fingermark detection. The latent fingermarks on several surfaces labeled with C-dots@SiO2fingermark powders emitted blue fluorescence under 365[Formula: see text]nm UV light and exhibited high contrast between the background and the ridges. Additionally, the C-dots@SiO2fingermark powder as a fluorescent label for enhancing latent fingermarks demonstrated greater advantages as compared to the conventional fluorescent fingermark powder especially for latent fingermark deposited on porous surfaces.

Synthesis and Characterization of SiO2@Y2MoO6:Eu3+ Core–Shell Structured Spherical Phosphors by Sol–Gel Process

2016 ◽  
Vol 16 (4) ◽  
pp. 3914-3920 ◽  
Author(s):  
G. Z Li ◽  
F. H Liu ◽  
Z. S Chu ◽  
D. M Wu ◽  
L. B Yang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Annealing Temperature ◽  
Uv Light ◽  
Sol Gel ◽  
Spherical Shape ◽  
Core Shell ◽  
X Ray ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
Average Size

SiO2@Y2MoO6:Eu3+ core–shell phosphors were prepared by the sol–gel process. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectra (EDS), transmission electron microscopy (TEM), photoluminescence (PL) spectra as well as kinetic decays were used to characterize the resulting SiO2@Y2MoO6:Eu3+ core–shell phosphors. The XRD results demonstrated that the Y2MoO6:Eu3+ layers on the SiO2 spheres crystallized after being annealed at 700 °C and the crystallinity increased with raising the annealing temperature. The obtained core–shell phosphors have spherical shape with narrow size distribution (average size ca. 640 nm), non-agglomeration, and smooth surface. The thickness of the Y2MoO6:Eu3+ shells on the SiO2 cores could be easily tailored by varying the number of deposition cycles (70 nm for four deposition cycles). The Eu3+ shows a strong PL emission (dominated by 5D0–7F2 red emission at 614 nm) under the excitation of 347 nm UV light. The PL intensity of Eu3+ increases with increasing the annealing temperature and the number of coating cycles.

Synthesis and Characterization of Rare Earth (Tb3+ and Yb3+) Doped CdS/ZnS Core/Shell Nanocrystals for Enhanced Photovoltaic Efficiency

2011 ◽  
Vol 1322 ◽  
Author(s):  
Sandip Das ◽  
Krishna C. Mandal
Keyword(s):  
Rare Earth ◽  
Uv Light ◽  
Core Shell ◽  
X Ray Diffraction ◽  
Chemical Route ◽  
X Ray ◽  
Broadband Absorption ◽  
Photovoltaic Efficiency ◽  
Transmission Electron

ABSTRACTCdS host nanocrystals with 4.2-5.5 nm in diameter have been synthesized from air stable precursors via a synthetic chemical route and doped with rare earth (RE) terbium (Tb3+) and ytterbium (Yb3+) ions. RE3+-doped CdS cores were shelled by ZnS layers of different thicknesses. The resulting core/shell nanocrystals show a complete broadband absorption below 400-460 nm to the deep UV region depending on the size of the cores. RE3+-doped CdS nanocrystals showed a red shift in the emission as observed under irradiation of 302 nm UV light and was confirmed by room temperature photoluminescence (PL) measurements. The nanocrystals were further characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), and energy dispersive x-ray (EDX) analysis. The results show that these RE3+-doped nanocrystals can be used as solar spectral matching downconversion material to enhance photovoltaic efficiency of existing solar cells.

Synthesis and Properties of TiO2/ZnO Core/Shell Nanomaterials

2007 ◽  
Vol 119 ◽  
pp. 239-242 ◽  
Author(s):  
Xiao Li Zhang ◽  
Young Hwan Kim ◽  
Young Soo Kang
Keyword(s):  
Thin Layers ◽  
Core Shell ◽  
X Ray Diffraction ◽  
Visible Absorption ◽  
X Ray ◽  
Transmission Electron ◽  
Diffraction Peaks ◽  
Uv Visible ◽  
Zno Powder ◽  
Tio2 Phase

Core/shell structured TiO2/ZnO was synthesized in a basic aqueous solution through a simple hydrolyzing method. The powder X-ray diffraction (XRD) and transmission electron microscopy of the initial TiO2/ZnO powder showed diffraction peaks corresponding to the ZnO and TiO2 phase. The structure and thickness of ZnO shell (about 2.5 nm) coated TiO2 surface as thin layers or nanoclusters, depends upon the reactant concentration and the reaction time. The characteristics of the optical absorption were described by UV-visible absorption spectroscopy.

scholarly journals REMOVAL OF NORFLOXACIN BY TiO2-SBA-15 PHOTOCATALYST

2020 ◽  
Vol 58 (3A) ◽  
pp. 13
Author(s):  
Nguyễn Thị Thu Trang ◽  
Trần Quang Vinh ◽  
Nguyễn Thành Đồng ◽  
Phạm Tuấn Linh ◽  
Nguyễn Viết Hoàng ◽  
...  
Keyword(s):  
Uv Light ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
Surface Areas ◽  
Pluronic P123 ◽  
Adsorption Capacities ◽  
Transmission Electron ◽  
Photocatalytic Activities ◽  
Adsorption Desorption ◽  
Synthesized Materials

Ordered SBA-15 mesoporous silica support was synthesized by a sol-gel method using triblock copolymer Pluronic P123 and immobilized with different amounts of photocatalyst TiO2. The synthesized composites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and N2 adsorption-desorption isotherms. The synthesized materials possessed specific surface areas SBET of 768 m2/g, 544 m2/g, 421 m2/g and 333 m2/g at the TiO2:SiO2 ratio of 0, 0.25, 1.0 and 5.0, respectively. The adsorption capacities and photocatalytic activities under UV light irradiation of these materials were evaluated for Norfloxacin degradation. Experimental results indicate that the highest activity was observed on the sample with TiO2:SiO2 ratio of 1.

scholarly journals Conductivity Research on ABS & PC Converted Core Shell Quantum Dot Doped in ABS & PC

2019 ◽  
Vol 8 (4) ◽  
pp. 7740-7742
Keyword(s):  
Quantum Dot ◽  
Core Shell ◽  
X Ray Diffraction ◽  
Visible Absorption ◽  
X Ray ◽  
Transmission Electron ◽  
Wet Chemical ◽  
Uv Visible ◽  
Lcr Meter ◽  
Absorption Characteristics

Zns: Mn / ZnO inverted shell quantum dots have been synthesized using a wet chemical process.The study used Mn of 4 percent weight. Transmission Electron Microscope (TEM) images show a 50 nm order for the quantum dot size. Confirmation of the ZnO capped ZnSMn was done by TEM and X ray diffraction (XRD).The test band distance is measured using the UV Visible absorption characteristics. Measurement of the dielectric constant is done using the LCR meter

Synthesis and Characterization of SiO2/ZnO Core-Shell Spheres

2011 ◽  
Vol 320 ◽  
pp. 140-145
Author(s):  
Yung Kuan Tseng ◽  
Pei Han Wang ◽  
Shun Lung Su
Keyword(s):  
Uv Light ◽  
Spherical Surface ◽  
Sol Gel ◽  
Xrd Analysis ◽  
Core Shell ◽  
Visible Absorption ◽  
Stöber Method ◽  
Eds Analysis ◽  
Uv Visible

This Study applies to Stöber method for synthesis an characterization of even-sized SiO2micrometer sphere; and then applies to sol-gel method for encapsulation for one layer of ZnO at SiO2spherical surface after regarded it as core so that synthesis SiO2/ZnO core-shell spheres successfully. And observe morphology by FE-SEM and crossection by TEM. The TEM specimen were cut by two-beam FIB. Besides, EDS, XRD and UV-Visible spectroscopy were using for the analysis of composition, crystallization structure, and absorption spectrum, respectively. Experimental results showed that, SiO2spherical surface became smooth after deposition for zinc oxide. The specimen made by FIB more obviously was observed for core-shell distribution by TEM. EDS analysis made us clearly see shell signal with ZnO content, but core signal only is SiO2content. XRD analysis indicated its core-shell sphere signal possessing ZnO content, but UV-Visible absorption spectrometer displayed ZnO has been absorbed in range of UV light, in contrast, it is not absorbed in range of visible light.

Preparation of luminescent inorganic core/shell-structured nanoparticles

2011 ◽  
Vol 1342 ◽  
Author(s):  
Moritz Milde ◽  
Sofia Dembski ◽  
Sabine Rupp ◽  
Carsten Gellermann ◽  
Gerhard Sextl ◽  
...  
Keyword(s):  
Sol Gel ◽  
Core Shell ◽  
X Ray Diffraction ◽  
Coating Solution ◽  
Transmission Electron ◽  
Composition And Structure ◽  
Sol Gel Process ◽  
Shell Composition ◽  
Diffraction Patterns ◽  
Process Annealing

ABSTRACTSiO2 nanoparticles (NPs) were coated with Eu3+-doped calcium phosphate (CP) and Mn2+-doped ZnO to give Zn2SiO4 via a modified Pechini sol-gel process. Annealing at high temperatures resulted in NPs with an amorphous core and a crystalline luminescent shell. It was shown that this procedure can be applied to silica cores with diameters below 300 nm. By transmission electron microscopy, elemental analysis and from X-ray diffraction patterns it was determined that shell composition and structure are influenced by the annealing temperature and pH of the coating solution. Measurements of photoluminescence intensities displayed their dependency on the concentration of dopant in the resulting core/shell NPs.

Optical and Magnetic Studies of Fe3O4/Au Core/Shell Nanocomposites

2019 ◽  
Vol 18 (05) ◽  
pp. 1850033 ◽  
Author(s):  
Al-Sayed A. M. Al-Sherbini ◽  
Gamal El-Ghannam ◽  
Hesham Yehya ◽  
O. Aied Nassef
Keyword(s):  
Shell Structures ◽  
Core Shell ◽  
X Ray Diffraction ◽  
Magnetic Studies ◽  
Visible Absorption ◽  
The Core ◽  
Transmission Electron ◽  
Surface Poisoning ◽  
Shell Particles

In this paper, we report the synthesis of Fe3O4 nanoparticles which are resistant to surface poisoning, has been adopted. Fe3O4 nanoparticles have been successfully coated with Au in the form of a shell with different sizes (Fe3O4/Au Core/Shell). Adjustment of the components’ ratio makes the shell thickness of the core/shell particles tunable. Thus, the presented route yields well-defined core/shell structures of different sizes in the range 15–57[Formula: see text]nm with varying the proportion of Au noble metal to Fe3O4 nanoparticles. The UV-Visible absorption spectra, X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) were applied for the characterization of the formed core/shell structures. Moreover, magnetic properties of the core/shell nanocomposites were also studied using Vibrating Sample Magnetometry (VSM).

scholarly journals Obtaining and Characterization of TiO2-GO Composites for Photocatalytic Applications

2020 ◽  
Vol 2020 ◽  
pp. 1-9 ◽  
Author(s):  
D. K. Calvo Ramos ◽  
M. Vega González ◽  
R. A. Esparza Muñóz ◽  
J. Santos Cruz ◽  
F. J. De Moure-Flores ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Uv Radiation ◽  
Uv Light ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission

Titanium dioxide (TD) and graphene oxide (GO) were synthesized by sol-gel and improved Hummers method, respectively. This study shows the results of the incorporation through four different conditions (sol-gel, sol-gel and ultrasonic, annealed, and UV radiation, C1 to C4, respectively). It was observed that a homogeneous incorporation of TD on sheets of GO was obtained satisfactorily. The composites of TiO2/GO were characterized using different techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), energy dispersive X-ray spectroscopy (EDS), Raman spectroscopy, and infrared spectroscopy (IR). The photocatalytic activity of the composites was determined from the degradation of the dye azo tartrazine using UV and solar radiation. The best incorporation of TD nanoparticles on GO was obtained with condition C3 (thermal incorporation method) at a temperature of 65°C. This shows a uniformity in the size and shape of the TD as well as an excellent adherence to the sheet of GO. This addition is accomplished by ionic bonding in the presence of electrostatic Coulomb forces. The C3 composite degraded the tartrazine dye using UV radiation and sunlight. With the latter, the degradation time was three times faster than using UV light.

A Novel CuO-TiO2 Composite Photocatalyst and its Degradation of Methyl Orange under UV Irradiation

2011 ◽  
Vol 295-297 ◽  
pp. 1129-1132 ◽  
Author(s):  
Shi De Wu ◽  
You Qi Zhu ◽  
Chao Li ◽  
Ying Liang Wei
Keyword(s):  
Electron Microscopy ◽  
Methyl Orange ◽  
Uv Light ◽  
Sol Gel ◽  
High Catalytic Activity ◽  
X Ray Diffraction ◽  
Composite Photocatalyst ◽  
Uv Light Irradiation ◽  
Transmission Electron ◽  
Degradation Of Methyl Orange

A novel CuO-TiO2 composite photocatalyst was prepared by a redox process coupling with sol-gel method. The morphology and structure of the as-prepared samples were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Photocatalytic activity of the CuO-TiO2 composite photocatalyst was evaluated in terms of the degradation of Methyl orange (MO) in aqueous solution under UV light irradiation. The results show that the as-prepared composite consisted of monoclinic-phase CuO-nanotubes and TiO2 nanoparticles, in which TiO2 nanoparticles were dramatically decorated on the CuO-nanotubes, exhibits a high catalytic activity to decolorize MO. According to the experimental results, 1.27wt % was the optimal loading for CuO-doped TiO2 photocatalyst.

Sign in / Sign up

Export Citation Format

Share Document