scholarly journals Carbon Quantum Dots Modified (002) Oriented Bi2O2CO3 Composites with Enhanced Photocatalytic Removal of Toluene in Air

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1795
Author(s):  
Junping Ding ◽  
Huanchun Wang ◽  
Yidong Luo ◽  
Yushuai Xu ◽  
Jinsheng Liu ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Photoelectron Spectroscopy ◽  
Removal Rate ◽  
Carbon Quantum Dots ◽  
Spherical Particles ◽  
Chemical Route ◽  
X Ray ◽  
Photocatalytic Removal ◽  
Efficient Charge ◽  
Gaseous Toluene

In work, (002) oriented flower-like Bi2O2CO3(BOC) composites are synthesized by a facile chemical route and carbon quantum dots (CQDs) are modified on their surfaces through a hydrothermal method. The synthesized samples (CQD/BOC) are characterized by X-ray diffraction (XRD), SEM, X-ray photoelectron spectroscopy (XPS), UV-Vis diffuser reflectances (DRS), BET and TEM/HRTEM. The morphologies of CQD/BOC composites are the flower-like shapes, the irregular flaky structures and the fine spherical particles of CQDs attached. Photocatalytic performances were investigated in terms of removing gaseous toluene at a concentration of 94.3ppm in air, with the assistance of CQD/BOC under artificial irradiation. Our results show that CQDs modified (002) oriented Bi2O2CO3 exhibits good photocatalytic activity for toluene decomposition, which can be attributed to the enhanced efficient charge separation. A certain ratio composite photocatalyst (BOC-CQD-15) shows a toluene removal rate of 96.62% in three hours, as well as great stability. CO2 was verified to be the primary product. The oriented flower-like Bi2O2CO3 with carbon quantum dots on the surface shows great potential in the field of solar driven air purification.

scholarly journals The Application of Green-Synthesis-Derived Carbon Quantum Dots to Bioimaging and the Analysis of Mercury(II)

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Qianchun Zhang ◽  
Xiaolan Zhang ◽  
Linchun Bao ◽  
Yun Wu ◽  
Li Jiang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Hela Cells ◽  
Photoelectron Spectroscopy ◽  
Water Solubility ◽  
Limit Of Detection ◽  
Carbon Quantum Dots ◽  
Coefficient Of Determination ◽  
Serum Samples ◽  
X Ray ◽  
Transmission Electron

Ginkgo leaves were used as precursors for the hydrothermal synthesis of carbon quantum dots (CQDs), which were subsequently characterized by transmission electron microscopy as well as Fourier-transform infrared, X-ray powder diffraction, and X-ray photoelectron spectroscopy. The prepared CQDs exhibited a fluorescence quantum yield of 11% and superior water solubility and fluorescence stability, as well as low cytotoxicities and excellent biocompatibilities with A549 and HeLa cells; these CQDs were also used to bioimage HeLa cells. Moreover, owing to the experimental observation that Hg2+ quenches the fluorescence of the CQDs in a specific and sensitive manner, we developed a method for the detection of Hg2+ using this fluorescence sensor. The sensor exhibited a linear range for Hg2+ of 0.50–20 μM, with an excellent coefficient of determination (R2 = 0.9966) and limit of detection (12.4 nM). In practice, the proposed method was shown to be highly selective and sensitive for the monitoring of Hg2+ in lake water and serum samples.

PREPARATION OF Au-LOADED TiO2 BY PHOTOCHEMICAL DEPOSITION AND OZONE PHOTOCATALYTIC DECOMPOSITION

2006 ◽  
Vol 13 (01) ◽  
pp. 51-55 ◽  
Author(s):  
PANKE HE ◽  
MIN ZHANG ◽  
DONGMEI YANG ◽  
JIANJUN YANG
Keyword(s):  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Au Nanoparticles ◽  
Diffuse Reflectance Spectroscopy ◽  
Removal Rate ◽  
Photocatalytic Decomposition ◽  
X Ray ◽  
Transmission Electron ◽  
Photocatalytic Removal ◽  
Photochemical Deposition

In this paper, Au -loaded TiO 2( Au/TiO 2) photocatalysts were prepared by photochemical deposition method and characterized by transmission electron microscopy, diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy. The results indicated the metallic Au nanoparticles were deposited on the surface of TiO 2 after the high-pressure mercury irradiation and regarded as an electronegative center. The photocatalytic decomposition of gaseous ozone was investigated on TiO 2 and Au -loaded TiO 2 at room temperature. Results indicated that the photocatalytic conversion of ozone can be improved by Au/TiO 2 and photocatalytic activity increased with the increase of the photodeposition time. The photocatalytic removal rate of ozone remained above 96% on the surface of 1% Au/TiO 2 with photodeposition for 120 min under black lamp irradiation for 20 h. Au cluster deposited on the surface of TiO 2 functioned not only as the electron trap center but also as the adsorption site of O 3 in photocatalytic reaction.

scholarly journals Mesoporous Tungsten Trioxide Photoanodes Modified with Nitrogen-Doped Carbon Quantum Dots for Enhanced Oxygen Evolution Photo-Reaction

Nanomaterials ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1502 ◽  
Author(s):  
Mabrook S. Amer ◽  
Prabhakarn Arunachalam ◽  
Abdullah M. Al-Mayouf ◽  
Saradh Prasad ◽  
Matar N. Alshalwi ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Charge Carrier ◽  
Oxygen Evolution ◽  
Photoelectron Spectroscopy ◽  
Tungsten Trioxide ◽  
High Surface ◽  
Carbon Quantum Dots ◽  
Transmission Microscopy ◽  
X Ray ◽  
Carrier Separation

Nanostructured photoanodes are attractive materials for hydrogen production via water photo-electrolysis process. This study focused on the incorporation of carbon quantum dots doped with nitrogen as a photosensitizer into mesoporous tungsten trioxide photoanodes (N-CQD/meso-WO3) using a surfactant self-assembly template approach. The crystal structure, composition, and morphology of pure and N-CQD- modified mesoporous WO3 photoanodes were investigated using scanning electron and transmission microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Due to their high surface area, enhanced optical absorption, and charge-carrier separation and transfer, the resulting N-CQD/meso-WO3 photoanodes exhibited a significantly enhanced photocurrent density of 1.45 mA cm−2 at 1.23 V vs. RHE under AM 1.5 G illumination in 0.5 M Na2SO4 without any co-catalysts or sacrificial reagent, which was about 2.23 times greater than its corresponding pure meso-WO3. Moreover, the oxygen evolution onset potential of the N-CQD/meso-WO3 photoanodes exhibited a negative shift of 95 mV, signifying that both the charge-carrier separation and transfer processes were promoted.

Structural Modelling of Hybrid ZnO–CdSe Nano-Compounds Using X-ray Photoelectron Spectroscopy Depth-Profiling Technique

2020 ◽  
Vol 20 (6) ◽  
pp. 3741-3753
Author(s):  
Shefali Jain ◽  
Akanksha Singh ◽  
Mahesh Kumar ◽  
Shailesh Narain Sharma
Keyword(s):  
Quantum Dots ◽  
Zno Nanoparticles ◽  
Photoelectron Spectroscopy ◽  
Depth Profiling ◽  
Injection Technique ◽  
Chemical Route ◽  
X Ray ◽  
Exact Position ◽  
Varied Size ◽  
20 Nm

In the present work, ZnO nanoparticles were synthesized using chemical route method. Composition ratio for Zn:O and various oxidation states were determined using XPS (X-ray photoelectron spectroscopy) technique. The 1 hr calcined ZnO nanoparticles were found to the best due to their monodispersed nature (size ˜20 nm) and high purity. These nanoparticles were then used for synthesizing ZnO–CdSe nano-compounds. These nanocrystals were integrated with CdSe qdots (synthesized using Hot-Injection technique) of varied size (5 nm and 8 nm) via MPA (mercaptopropionic acid) as a linker to develop hybrid nano-compounds for photoactive applications like Quantum Dot sensitized solar cells (QDSSC’s) etc. Here, the main objective of the work was to explore the structure of hybrid nano-compounds. XPS-depth-profiling technique was used as an investigation technique for the compositional and structural analyses of ZnO–CdSe nano-compounds. The compositional structure was analyzed layer wise (obtained by etching at different time of sputtering) for the exact position of ZnO and CdSe nanoparticles. On the basis of above study utilizing depth profiling technique of XPS and TEM images, it was found that high quality of hybrid nano-compounds can be synthesized with smaller sized quantum dots, as compared to larger sized quantum dots because of unbounded phosphorus (P) and selenium (Se). Also, it confirms the role of linker that strengthens the binding of CdSe quantum dots on the surface of ZnO thus making it hard to separate the anchored, interstitial CdSe completely which paves the way for the development of stoichiometric, structurally and morphologically-stable ZnO–CdSe nano-compounds.

Preparation of Novel Ag–Si–TiO2 Composite and Research on Its Photocatalytic Degradation of Formaldehyde

2021 ◽  
Vol 13 (3) ◽  
pp. 371-380
Author(s):  
Yongjun Wu ◽  
Nina Xie ◽  
Lu Yu
Keyword(s):  
Photoelectron Spectroscopy ◽  
Removal Rate ◽  
Sol Gel ◽  
Catalytic Performance ◽  
Formaldehyde Concentration ◽  
Order Kinetic ◽  
Solution Ph ◽  
Visible Absorption ◽  
X Ray ◽  
Co Doped

A novel Ag–Si–TiO2 composite was prepared via sol–gel method for removing residual formaldehyde in shiitake mushroom. The structure of Ag–Si–TiO2 composite was characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses. Ultraviolet-visible absorption spectroscopy (UV-Vis) and N2 adsorption-desorption tests showed that Ag and Si co-doped decreased the band gap, the Brunauer-Emmett-Teller (BET) specific surface area of the samples increased and the recombination probability of electron-hole pairs (e--h+) reduced. Effect on removal rate of formaldehyde with different Ag-Si co-doped content, formaldehyde concentration and solution pH were investigated, and the results showed that 6.0 wt%Ag-3.0 wt%Si-TiO2 samples had an optimum catalytic performance, and the degradation efficiency reached 96.6% after 40 W 365 nm UV lamp irradiation for 360 min. The kinetics of formaldehyde degradation by Ag–Si–TiO2 composite photocatalyst could be described by Langmuir-Hinshelwood first-order kinetic model.

scholarly journals Porous Carbon Materials Obtained by the Hydrothermal Carbonization of Orange Juice

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 655 ◽  
Author(s):  
Francesco Veltri ◽  
Francesca Alessandro ◽  
Andrea Scarcello ◽  
Amerigo Beneduci ◽  
Melvin Arias Polanco ◽  
...  
Keyword(s):  
Porous Carbon ◽  
Photoelectron Spectroscopy ◽  
Orange Juice ◽  
Carbon Materials ◽  
Sorption Isotherms ◽  
Hydrothermal Carbonization ◽  
Carbon Quantum Dots ◽  
Energy Storage Devices ◽  
X Ray ◽  
Porous Carbon Materials

Porous carbon materials are currently subjected to strong research efforts mainly due to their excellent performances in energy storage devices. A sustainable process to obtain them is hydrothermal carbonization (HTC), in which the decomposition of biomass precursors generates solid products called hydrochars, together with liquid and gaseous products. Hydrochars have a high C content and are rich with oxygen-containing functional groups, which is important for subsequent activation. Orange pomace and orange peels are considered wastes and then have been investigated as possible feedstocks for hydrochars production. On the contrary, orange juice was treated by HTC only to obtain carbon quantum dots. In the present study, pure orange juice was hydrothermally carbonized and the resulting hydrochar was filtered and washed, and graphitized/activated by KOH in nitrogen atmosphere at 800 °C. The resulting material was studied by transmission and scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and nitrogen sorption isotherms. We found porous microspheres with some degree of graphitization and high nitrogen content, a specific surface of 1725 m2/g, and a pore size distribution that make them good candidates for supercapacitor electrodes.

NdFe2O4 Nanoparticles: Synthesis, Characterization, and Magnetic Properties

2020 ◽  
Vol 12 (6) ◽  
pp. 810-814 ◽  
Author(s):  
Xiao-Lei Song ◽  
Yi-Lin Wu ◽  
Si-Ran Zhang ◽  
Zhi Chen ◽  
Yong-Gui Li
Keyword(s):  
Photoelectron Spectroscopy ◽  
Solvothermal Method ◽  
Energy Dispersive Spectrometer ◽  
Reaction Times ◽  
Spherical Particles ◽  
Vibrating Sample Magnetometer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Magnetic Parameters ◽  
Transmission Electron

Multi-structured NdFe2O4 magnetic nanoparticles (NPs) were successfully prepared at different reaction times through a convenient solvothermal method. The microstructure and elemental composition of the NPs were characterized using powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) technique. An energy dispersive spectrometer (EDS) was connected to a scanning electron microscope to determine the weight and atomic percent of the prepared products. Subsequently, high-resolution transmission electron microscopy (HR/TEM) and TEM were performed at 3, 7, 11, and 15 h to elucidate the synthetic mechanism of the rare-earth element Nd doped in Fe3O4. The magnetic activities of the NPs were evaluated using a vibrating sample magnetometer (VSM). XRD, EDS, and XPS analyses show that Nd was successfully doped into Fe3O4 without breaking its crystal structure. Procedural single-crystal nanosheets and final spherical particles of NdFe2O4 were verified by TEM. The magnetic parameters of the products were further analyzed using the VSM.

Laser Induced Decomposition of Triethylgallium and Trimethylgallium Adsorbed on GaAs(100)

1988 ◽  
Vol 129 ◽  
Author(s):  
J. A. Mccaulley ◽  
V. R. Mccrary ◽  
V. M. Donnelly
Keyword(s):  
Excimer Laser ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Electronic Excitation ◽  
Removal Rate ◽  
Laser Wavelength ◽  
High Fluence ◽  
X Ray ◽  
Two Photon ◽  
Induced Decomposition

ABSTRACTWe report X-ray photoelectron spectroscopy (XPS) studies of excimer laser stimulated decomposition of triethylgallium (TEGa) and trimethylgallium (TMGa) adsorbed on Gastabilized GaAs(100) surfaces in ultrahigh vacuum. TEGa and TMGa dissociatively chemisorb on GaAs at room temperature, whereupon irradiation by an excimer laser (at 193 or 351 nm) leads to further dissociation and desorption of carbon-containing species. The carbon removal rate (per laser pulse) decreases as carbon is removed suggesting multiple reaction sites, coverage dependent Arrhenius parameters, or second-order reactions. Based on the dependence of the rate on laser wavelength and fluence, we conclude that at low fluence, a two-photon electronic excitation of the adsorbate occurs, while at high fluence, laser induced pyrolysis dominates.

scholarly journals Removal of methyl orange (MO) using carbon quantum dots (CQDs) derived from watermelon rinds

2019 ◽  
Vol 6 (1) ◽  
pp. 91-99
Author(s):  
Azrina Abd Aziz ◽  
U.R. Ramzilah
Keyword(s):  
Quantum Dots ◽  
Methyl Orange ◽  
Photocatalytic Degradation ◽  
Degradation Rate ◽  
Photocatalytic Performance ◽  
Carbon Quantum Dots ◽  
Facile Hydrothermal Method ◽  
X Ray ◽  
Degradation Activity ◽  
Scanning Electron

In this study, carbon quantum dots (CQDs) was prepared via a facile hydrothermal method. The objective for this study is to assess the performance of CQDs in photocatalytic degradation activity of methyl orange (MO) under artificial visible light source. For that reason, the prepared photocatalyst undergo further characterization by scanning electron microscope (SEM), energy dispersive X-ray spectroscope (EDX) and UV- Vis spectrophotometer (UV-VIS) to verify the morphology structure of the photocatalyst, elemental composition as well as the absorbance intensity, respectively. The results indicates that the prepared photocatalyst possess irregular porous shape with nanometre (nm) dimensions that can escalate the surface area for photocatalytic degradation activity. The elements of the photocatalyst mainly consist of carbon and oxygen as the major constituents in which necessary for photocatalytic activity with intense peak of absorbance intensity. The prepared CQDs also shows an excellent photocatalytic performance over the MO with degradation rate of 68.9% within 120 minutes.

scholarly journals Synthesis of Sulfur-Selenium Doped Carbon Quantum Dots for Biological Imaging and Scavenging Reactive Oxygen Species

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Guojie Huang ◽  
Yaqi Lin ◽  
Linxiu Zhang ◽  
Zhihong Yan ◽  
Yudong Wang ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Quantum Dots ◽  
Survival Rate ◽  
Photoelectron Spectroscopy ◽  
Reactive Oxygen ◽  
Carbon Quantum Dots ◽  
Hatching Rate ◽  
Oxygen Species ◽  
Transmission Electron ◽  
High Fluorescence

AbstractThe sulfur-selenium doped carbon quantum dots (S,Se-CQDs) were synthesized by one-step through hydrothermal method in this study, which have high fluorescence quantum yield (43%) and advanced ability to scavenge reactive oxygen species (ROS). They were characterized by transmission electron microscope (TEM), nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), fourier transform infrared spectroscopy (FTIR). The results showed that the clearance rate of free radical reached to 40% with 200 μg/mL of S,Se-CQDs. The antioxidant activity of S,Se-CQDs is related to -SH and Se-SH on carbon quantum dots. S,Se-CQDs were able to access to cells which is beneficial to enhance the removal efficiency to ROS. In the biocompatibility experiment, the cell survival rate exceeded 95%, there was little effect on hatching rate, survival rate and heart rate of zebrafish which demonstrated that S,Se-CQDs have an excellent biocompatibility. It prompts that S,Se-CQDs will has proud application prospects in the field of biomedicine.

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