Rapid and Eco-Friendly Synthesis of Red Fluorescent Gold Nanoclusters for Sensing and Anti-Counterfeiting Applications

NANO ◽  
2019 ◽  
Vol 14 (09) ◽  
pp. 1950121
Author(s):  
Lei Yan ◽  
Yanlin Yu
Keyword(s):  
Photoelectron Spectroscopy ◽  
Uv Light ◽  
Gold Nanoclusters ◽  
Synthesis Method ◽  
Operation Time ◽  
Experimental Conditions ◽  
Red Emission ◽  
X Ray ◽  
Vis Spectroscopy ◽  
Mw Irradiation

A rapid and eco-friendly synthesis method for the preparation of gold nanoclusters (Au NCs) with strong red emission has been developed. A one-pot microwave (MW) irradiation method yields bright red-emitting Au NCs, providing an easy route for the synthesis of fluorescent Au NCs without the need for a tedious operation, time-consuming procedure, or the use of toxic/corrosive agents and harsh conditions. The as-prepared Au NCs show a small-sized distribution, good dispersibility and a broad excitation band (from UV light to visible light). The optimal experimental conditions, including concentrations and order of addition of Na2CO3, bovine serum albumin (BSA), and HAuCl4 and the time of MW irradiation, were investigated in detail. The as-synthesized Au NCs were well characterized by fluorescence spectroscopy, UV-Vis spectroscopy, infrared spectroscopy, high-resolution transmission electron microscopy-energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction. Due to favorable photoluminescence features as well as minimal toxicity, the Au NCs could be applied to sensing, patterning and anti-counterfeiting. The Au NCs displayed strong red emission that was efficiently quenched by hydrogen peroxide (H2O[Formula: see text]. More strikingly, the obtained Au NCs were used as a fluorescent ink for producing luminescent handwriting and patterns, which may expand the potential applications of Au NCs in the fabrication of security inks.

scholarly journals Pyrolytic Formation of TiO2/Carbon Nanocomposite from Kraft Lignin: Characterization and Photoactivities

Catalysts ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 270
Author(s):  
Dhanalakshmi Vadivel ◽  
Diego Savio Branciforti ◽  
Andrea Speltini ◽  
Michela Sturini ◽  
Vittorio Bellani ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Uv Light ◽  
Tap Water ◽  
Aqueous Media ◽  
Pyrolytic Carbon ◽  
Kraft Lignin ◽  
X Ray Diffraction ◽  
Experimental Conditions ◽  
Paramagnetic Resonance ◽  
X Ray

This article reports on the formation of pyrolytic carbon/TiO2 nanocomposite (p-C/TiO2) by pyrolysis of a mixture of the P25 TiO2 and kraft lignin at 600 °C. The result was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, UV-visible spectroscopy, electron paramagnetic resonance spectrometry (EPR), thermogravimetry (TGA) and SEM microscopy. Its photocatalytic activity was ascertained using three classes of chemical probes, namely (i) degradation of methylene blue (MB) and rhodamine-B (RhB) dyes in UV light-irradiated aqueous suspensions, (ii) depletion of phenol and (iii) degradation of antibiotics. The p-C/TiO2 nanocomposite is a strong phisisorbent of both MB and RhB nearly twofold with respect to neat TiO2. Although it is nearly twofold more photoactive toward the degradation of MB (0.091 min−1 versus 0.047 min−1), it is not with regard to RhB degradation (0.064 min−1 versus 0.060 min−1). For the degradation of phenol in aqueous media (pH 3), pristine TiO2 was far more effective than p-C/TiO2 for oxygenated suspensions (17.6 × 10−3 mM min−1 versus 4.3 × 10−3 mM min−1). Under an argon atmosphere, the kinetics were otherwise identical. The activity of the material was tested also for a real application in the degradation of a fluoroquinolone antibiotic such as enrofloxacin (ENR) in tap water. It is evident that the photoactivity of a semiconductor photocatalyst is not a constant, but it does depend on the nature of the substrate used and on the experimental conditions. It is also argued that the use of dyes to assess photocatalytic activities when suspensions are subjected to visible light irradiation is to be discouraged as the dyes act as electron transfer photosensitizers and or can undergo photodegradation from their excited states.

scholarly journals Synthesis and Characterization of CdS/TiO2-Montmorillonite Nanocomposite with Enhanced Visible-Light Absorption

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Feng-shan Zhou ◽  
Dai-mei Chen ◽  
Bao-lin Cui ◽  
Wei-heng Wang
Keyword(s):  
Visible Light ◽  
Light Absorption ◽  
Photoelectron Spectroscopy ◽  
Synthesis Method ◽  
Cds Nanoparticles ◽  
X Ray Diffraction ◽  
Visible Light Absorption ◽  
X Ray ◽  
Vis Spectroscopy ◽  
Adsorption Desorption

Sodium montmorillonite (MMT) was chosen as the carrier; a serial of CdS/TiO2-MMT nanocomposites with enhanced visible-light absorption ability was prepared by hydrothermal synthesis method combination with semiconductor compound modification method. The samples are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and ultraviolet visible (UV-Vis) spectroscopy; the results showed that TiO2and CdS nanoparticles were loaded on the surface of montmorillonite uniformly. N2adsorption-desorption experiment showed that the specific surface area of TiO2/montmorillonite nanocomposite made by this method can reach 200 m2/g and pore-size distribution was from 4 to 6 nm; UV-Vis showed that the recombination of CdS and TiO2enhanced visible-light absorption ability of samples of TiO2/montmorillonite and visible-light absorption ability increase with the increased of the adsorption of CdS.

Ti-Co mixed oxide as photocatalysts in the generation of hydrogen from water

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Alejandro Pérez-Larios ◽  
Isabel Torres-Ramos ◽  
Rodolfo Zanella ◽  
José Luis Rico
Keyword(s):  
Electron Microscope ◽  
Photoelectron Spectroscopy ◽  
Mixed Oxides ◽  
Uv Light ◽  
Energy Dispersive Spectrometer ◽  
Sol Gel ◽  
X Ray ◽  
Surface Areas ◽  
Vis Spectroscopy ◽  
Xrd Patterns

Abstract The effect of Co into the titanium oxide matrix as photocatalysts in the generation of hydrogen from water is herein reported. Ti–Co mixed oxides and pure titania were synthetized by sol-gel. The Co content was 0, 1, 3, 5, and 10 wt.%. The solids were characterized by Scanning electron microscope-energy dispersive spectrometer (SEM-EDS), N2 physisorption, X-ray difrraction (XRD), ultraviolet visible spectroscopy (UV–Vis), spectroscopy Raman, X-ray photoelectron spectroscopy (XPS) spectroscopy and High resolution transmission electron microscope (HRTEM). The results showed that the mixed oxides show larger specific surface areas (73–186 m2/g) compare to that of pure TiO2 (64 m2/g). The XRD patterns of the Ti-Co samples resemble that of anatase and segregation of Co was not observed by this technique. The band gap energies of these solids vary from 3.05 to 2.85 eV which are smaller than that of pure TiO2 (3.2 eV). The Ti-Co oxides showed an enhancement in the hydrogen production (∼3056 μmol/h) compare to that of TiO2 (190 μmol/h) when using UV light. Furthermore, the photocatalytic activity of titania (110 μmol/h) for this reaction was also smaller than those observed for the Ti-Co mixed oxides (∼4056 μmol/h) under visible light.

scholarly journals Hybrid Nanoparticles Based on Cobalt Ferrite and Gold: Preparation and Characterization

2021 ◽  
Author(s):  
Svetlana Saikova ◽  
Alexander Pavlikov ◽  
Tatyana Trofimova ◽  
Yuri Mikhlin ◽  
Denis Karpov ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Cobalt Ferrite ◽  
Magnetic Measurements ◽  
Average Particle Size ◽  
Gold Nanoclusters ◽  
Hybrid Nanoparticles ◽  
Gold Deposition ◽  
Average Particle ◽  
X Ray ◽  
Vis Spectroscopy

During the past few decades, hybrid nanoparticles (HNPs) based on a magnetic material and gold have attracted interest for applications in catalysis, diagnostics and nanomedicine. In this paper, magnetic CoFe2O4/Au HNPs with an average particle size of 10–20 nm decorated with 2-nm gold clusters were prepared using methionine as a reducer and an anchor between CoFe2O4 and gold. The obtained nanoparticles were studied by X-Ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR) spectroscopy and X-Ray photoelectron spectroscopy (XPS) and UV-Vis spectroscopy techniques. The TEM images of the HNPs obtained after one, six and ten gold deposition cycles showed that the surface of cobalt ferrite was covered with gold nanoclusters, which slightly increased with an increase in the number of gold deposition cycles (from 2.12 ± 0.15 nm after one cycle to 2.46 ± 0.13 nm after ten cycles) without any change in surface density. The magnetic measurements showed that the obtained HNPs possessed typical ferrimagnetic behaviour, which corresponds to that of CoFe2O4 nanoparticles. The toxicity evaluation of the synthesised HNPs on Chlorella vulgaris indicated that they can be applied to biomedical applications such as magnetic hyperthermia, photothermal therapy, drug delivery, bioimaging and biosensing.

scholarly journals Efficient Adsorption of Methylene Blue by Porous Biochar Derived from Soybean Dreg Using a One-Pot Synthesis Method

Molecules ◽  
2021 ◽  
Vol 26 (3) ◽  
pp. 661
Author(s):  
Zhiwei Ying ◽  
Xinwei Chen ◽  
He Li ◽  
Xinqi Liu ◽  
Chi Zhang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Methylene Blue ◽  
Photoelectron Spectroscopy ◽  
Synthesis Method ◽  
Urban Pollution ◽  
Maximum Adsorption Capacity ◽  
One Pot ◽  
Average Pore ◽  
X Ray ◽  
Isotherm Equation

Soybean dreg is a by-product of soybean products production, with a large consumption in China. Low utilization value leads to random discarding, which is one of the important sources of urban pollution. In this work, porous biochar was synthesized using a one-pot method and potassium bicarbonate (KHCO3) with low-cost soybean dreg (SD) powder as the carbon precursor to investigating the adsorption of methylene blue (MB). The prepared samples were characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM), elemental analyzer (EA), Brunauer-Emmett-Teller (BET), X-ray diffractometer (XRD), Raman spectroscopy (Raman), Fourier transform infrared spectrometer (FTIR), and X-ray photoelectron spectroscopy (XPS). The obtained SDB-K-3 showed a high specific surface area of 1620 m2 g−1, a large pore volume of 0.7509 cm3 g−1, and an average pore diameter of 1.859 nm. The results indicated that the maximum adsorption capacity of SDB-K-3 to MB could reach 1273.51 mg g−1 at 318 K. The kinetic data were most consistent with the pseudo-second-order model and the adsorption behavior was more suitable for the Langmuir isotherm equation. This study demonstrated that the porous biochar adsorbent can be prepared from soybean dreg by high value utilization, and it could hold significant potential for dye wastewater treatment in the future.

scholarly journals Synthesis of Exosome-Based Fluorescent Gold Nanoclusters for Cellular Imaging Applications

2021 ◽  
Vol 22 (9) ◽  
pp. 4433
Author(s):  
Eun Sung Lee ◽  
Byung Seok Cha ◽  
Seokjoon Kim ◽  
Ki Soo Park
Keyword(s):  
Photoelectron Spectroscopy ◽  
Low Cost ◽  
Stokes Shift ◽  
Gold Nanoclusters ◽  
Human Colon ◽  
Cellular Imaging ◽  
Metal Nanoclusters ◽  
Human Colon Cancer ◽  
X Ray ◽  
High Concentrations

In recent years, fluorescent metal nanoclusters have been used to develop bioimaging and sensing technology. Notably, protein-templated fluorescent gold nanoclusters (AuNCs) are attracting interest due to their excellent fluorescence properties and biocompatibility. Herein, we used an exosome template to synthesize AuNCs in an eco-friendly manner that required neither harsh conditions nor toxic chemicals. Specifically, we used a neutral (pH 7) and alkaline (pH 11.5) pH to synthesize two different exosome-based AuNCs (exo-AuNCs) with independent blue and red emission. Using field-emission scanning electron microscopy, energy dispersive X-ray microanalysis, nanoparticle tracking analysis, and X-ray photoelectron spectroscopy, we demonstrated that AuNCs were successfully formed in the exosomes. Red-emitting exo-AuNCs were found to have a larger Stokes shift and a stronger fluorescence intensity than the blue-emitting exo-AuNCs. Both exo-AuNCs were compatible with MCF-7 (human breast cancer), HeLa (human cervical cancer), and HT29 (human colon cancer) cells, although blue-emitting exo-AuNCs were cytotoxic at high concentrations (≥5 mg/mL). Red-emitting exo-AuNCs successfully stained the nucleus and were compatible with membrane-staining dyes. This is the first study to use exosomes to synthesize fluorescent nanomaterials for cellular imaging applications. As exosomes are naturally produced via secretion from almost all types of cell, the proposed method could serve as a strategy for low-cost production of versatile nanomaterials.

scholarly journals Synthesis of Ce1−xPdxO2−δ Solid Solution in Molten Nitrate

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 640
Author(s):  
Hideaki Sasaki ◽  
Keisuke Sakamoto ◽  
Masami Mori ◽  
Tatsuaki Sakamoto
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Solid Solutions ◽  
Photoelectron Spectroscopy ◽  
Synthesis Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Co Precipitation ◽  
Ionic States

CeO2-based solid solutions in which Pd partially substitutes for Ce attract considerable attention, owing to their high catalytic performances. In this study, the solid solution (Ce1−xPdxO2−δ) with a high Pd content (x ~ 0.2) was synthesized through co-precipitation under oxidative conditions using molten nitrate, and its structure and thermal decomposition were examined. The characteristics of the solid solution, such as the change in a lattice constant, inhibition of sintering, and ionic states, were examined using X-ray diffraction (XRD), scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM−EDS), transmission electron microscopy (TEM)−EDS, and X-ray photoelectron spectroscopy (XPS). The synthesis method proposed in this study appears suitable for the easy preparation of CeO2 solid solutions with a high Pd content.

ROOM TEMPERATURE PHOTOLUMINESCENCE OF POLYCRYSTALLINE SIC PREPARED FROM CARBON-SATURATED SI MELT

2002 ◽  
Vol 16 (06n07) ◽  
pp. 1047-1051
Author(s):  
JIANPING MA ◽  
ZHIMING CHEN ◽  
GANG LU ◽  
MINGBIN YU ◽  
LIANMAO HANG ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Uv Light ◽  
X Ray Diffraction ◽  
X Ray ◽  
Room Temperature Photoluminescence ◽  
Composition And Structure ◽  
Light Excitation ◽  
Scanning Electron

Intense photoluminescence (PL) has been observed at room temperature from the polycrystalline SiC samples prepared from carbon-saturated Si melt at a temperature ranging from 1500 to 1650°C. Composition and structure of the samples have been confirmed by means of X-ray photoelectron spectroscopy, X-ray diffraction and scanning electron microscopy. PL measurements with 325 nm UV light excitation revealed that the room temperature PL spectrum of the samples consists of 3 luminescent bands, the peak energies of which are 2.38 eV, 2.77 eV and 3.06 eV, respectively. The 2.38 eV band is much stronger than the others. It is suggested that some extrinsic PL mechanisms associated with defect or interface states would be responsible to the intensive PL observed at room temperature.

TiO2 anatase nanotubes for the purification of uranium,arsenic and lead containing water: an X-ray Photoelectron Spectroscopy study

2009 ◽  
Vol 1171 ◽  
Author(s):  
Marco Bonato ◽  
Kristin Vala Ragnarsdottir ◽  
Geoffrey C. Allen
Keyword(s):  
Photoelectron Spectroscopy ◽  
Uv Light ◽  
Carbonyl Complexes ◽  
Spectroscopy Study ◽  
High Adsorption ◽  
X Ray ◽  
Tio2 Anatase ◽  
Major Species ◽  
Titania Photocatalyst ◽  
Ph Range

AbstractTiO2 anatase nanotubes synthesised via anodic oxidation were used as adsorbent for the uptake of U and Pb from aqueous solution and the photoremoval of As(III). An X-ray photoelectron spectroscopy study of the sorbent medium surface revealed a high adsorption of U and Pb at pH 8. The adsorption of the uranyl ion was enhanced in an anoxy (N2) atmosphere, because this prevents the formation of very stable carbonyl complexes. As(III) was adsorbed on TiO2 but in the presence of O2 and UV light was oxidized to As(V). XPS analysis revealed that in the pH range 3-9 As(V) was always the major species detected at the surface of the titania photocatalyst.

Silver mirror reaction metallized chromatography paper for supercapacitor application

2021 ◽  
Author(s):  
I-Hsuan Chen ◽  
Jung-Hsien Chang ◽  
Ren-Jie Xie ◽  
Chia-Hui Tseng ◽  
Sheng-Rong Hsieh ◽  
...  
Keyword(s):  
Flexible Electronics ◽  
Photoelectron Spectroscopy ◽  
Cost Effective ◽  
Water Contact ◽  
X Ray ◽  
Supercapacitor Application ◽  
Resource Limited ◽  
Vis Spectroscopy ◽  
Silver Mirror ◽  
Silver Mirror Reaction

Abstract In this study, the easy-to-operate silver mirror reaction (SMR) was used for metallizing chromatography paper. The SMR-metallized paper was characterized by water contact angle measurements, a surface profiler, X-ray photoelectron spectroscopy, UV-vis spectroscopy, X-ray diffraction, and electrical resistance measurement. The characterization results show that Ag was successfully synthesized on cellulose fibers and was electrically conductive after cyclic bending. Moreover, this SMR-metallized paper was used as electrodes for fabricating a supercapacitor. This SMR-metallized paper could be used for realizing cost-effective flexible electronics applied in on-site biochemical sensing in resource-limited settings.

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