44 results on '"Kefayat A"'
Search Results
2. A review on graphene based transition metal oxide composites and its application towards supercapacitor electrodes
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Muhammad Ihrar, Won-Chun Oh, Syed Babar Hussain, Syed Zakir Hussain, and Kefayat Ullah
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Supercapacitor ,Materials science ,Thin layers ,Band gap ,Graphene ,General Chemical Engineering ,General Engineering ,Oxide ,General Physics and Astronomy ,law.invention ,chemistry.chemical_compound ,chemistry ,Transition metal ,law ,Electrode ,General Earth and Planetary Sciences ,General Materials Science ,Charge carrier ,Composite material ,General Environmental Science - Abstract
Two-dimensional (2D) graphene and its outstanding properties such as, enormous conductivities, mechanical strength, optical and electrical properties brought it one of the most studied materials for the production of energy using renewable resources. The composites of graphene with the same morphological materials such as layered transition metal oxides will be the most aspiring combination to boost their conducting, optoelectronic and mechanical properties. Furthermore, the transition metal chalcogenides materials attracted significant attention due to their atomically thin layers and enormous optical, conducting and electrical properties. The layered materials offer mostly atomically thin 2D plane to the charge carrier with superior conducting properties. The thickness at atomic level, band gap, spin orbit coupling electronic and optoelectronics properties of transition metal dichalcogenides makes them one of the promising entities in energy harvesting technologies. The review suggests some strategies to improve the transition metals-composites stability conducting properties to be tailored in various applications.
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- 2020
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3. Construction and characterization of a theranostic system based on graphene/manganese chelate
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Amirhosein Kefayat, Reza Karimi Shervedani, Marzieh Samiei Foroushani, Fatemeh Rahnemaye Rahsepar, and Mostafa Torabi
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Indoles ,Cell Survival ,Polymers ,Surface Properties ,Biomedical Engineering ,Biophysics ,Antineoplastic Agents ,02 engineering and technology ,010402 general chemistry ,Electrochemistry ,01 natural sciences ,Theranostic Nanomedicine ,Nanocomposites ,law.invention ,Mice ,Coordination Complexes ,law ,Cell Line, Tumor ,Animals ,Humans ,Chelation ,Particle Size ,Bovine serum albumin ,Fourier transform infrared spectroscopy ,Electrodes ,Chelating Agents ,Drug Carriers ,Manganese ,biology ,Graphene ,Chemistry ,Oxides ,Serum Albumin, Bovine ,Electrochemical Techniques ,General Medicine ,Pentetic Acid ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Dielectric spectroscopy ,Methotrexate ,Cancer cell ,biology.protein ,Graphite ,0210 nano-technology ,Selectivity ,Biotechnology ,Nuclear chemistry - Abstract
Construction of hybrid systems that combine the cancer treatment and diagnosis agents on a single platform, known as theranostic systems, have received great attentions in the field of nanobiomedicine. Here, construction and characterization of a new multifunctional hybrid theranostic system based on RGO, PDA, BSA, DTPA-Mn(II), and MTX constituents, is presented. Accordingly, GO is partially reduced and simultaneously functionalized by dopamine, leading to reduced graphene oxide/polydopamine, RGO-PDA system; and then, the bovine serum albumin protein (BSA) is grafted onto this system. The obtained system, RGO-PDA-BSA, is further decorated with diethylenetriaminepentaacetic acid-Mn(II) as diagnostic system and methotrexate as anticancer drug. Physicochemical characteristics of the RGO-PDA-BSA-DTPA-Mn(II)/MTX system are studied by Fourier transform infrared spectroscopy, atomic force microscopy, and electrochemical methods. The capturing ability of the prepared system for the cancer cells is evaluated through electrochemical impedance spectroscopy (EIS) and by using the 4T1 cancer cells in comparison with L929 normal cells. The EIS results indicate that a degree of selectivity as 6.23 for GC-RGO-PDA-BSA-DTPA-Mn(II)/MTX electrode system toward 4T1 cells, which is larger than that obtained for this system toward the L929 cells. Similar analysis performed using the GC-RGO-PDA-DTPA-Mn(II)/MTX system (having no BSA) indicate that the selectivity degree of the system is increased only by a factor of 1.6, implying that presence of BSA has increased the selectivity of the system for 4T1 cells by a factor of four. This behavior supports the crucial role of BSA in this process for 4T1 cells. Finally, the drug release study of RGO-PDA-BSA-DTPA-Mn(II)/MTX system is performed successfully at pH 7.4.
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- 2018
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4. Fabrication and enhancement in photoconductive response of $$\alpha$$ α -Fe2O3/graphene nanocomposites as anode material
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Naveed Alam, Yaqoob Khan, Arif Ullah, Won-Chun Oh, and Kefayat Ullah
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Photocurrent ,Materials science ,Nanocomposite ,Graphene ,Photoconductivity ,Nanoparticle ,02 engineering and technology ,Hematite ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,law.invention ,Anode ,Chemical engineering ,law ,visual_art ,visual_art.visual_art_medium ,Water splitting ,Electrical and Electronic Engineering ,0210 nano-technology - Abstract
We report a facile fabrication for the synthesis of graphene based α-Fe2O3 nanocomposites as anode material for photoelectrochemical water splitting. The effect of introduction of graphene as a solid-state electron material has been investigated in detail by controlling the synthesis parameters. The XRD pattern of hematite α-Fe2O3 nanoparticles were indexed to rhombohedral structure of α-Fe2O3, while the TEM images illustrate the flaky structure of graphene supported by hematite nanoparticles. The rGO/ $$\alpha$$ -Fe2O3 nanocomposites showed enhanced photocurrent of ~ 4 mA cm−2 at (1.23 V vs. RHE) under standard illumination conditions (AM 1.5 G 100 mW cm−2). The enhanced photoelectrochemical performance may be attributed to synergistic effect of graphene and $$\alpha$$ -Fe2O3 by improving the charge transport properties. The optical properties were also observed to be influenced by the coupling of rGO and α-Fe2O3 composites as witnessed in the DRS spectra.
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- 2018
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5. Progesterone Therapy for the Prevention of Preterm Labor in Women with Single Risk-factor: A Systematic Review and Meta-analysis
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Mohammad Amin Bahrami, Kefayat Chaman Ara, Sima Bahrami, Omid Barati, Mohammad Nabi Bahrami, Elham Bahrami, and Mahmood Moosazadeh
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medicine.medical_specialty ,Pregnancy ,lcsh:R5-920 ,Preterm labor ,Obstetrics ,business.industry ,lcsh:R ,Progesterone therapy ,Gestational age ,lcsh:Medicine ,General Medicine ,medicine.disease ,law.invention ,Randomized controlled trial ,law ,Meta-analysis ,medicine ,Risk factor ,Complication ,business ,lcsh:Medicine (General) ,keywords: preterm birth, preterm labor, previous preterm labor, progesterone, short cervical length - Abstract
Background: Preterm labor is a common complication of pregnancy which has become a main health concern around the world due to its negative consequences. Objective: To investigate the efficacy of progesterone therapy in the prevention of preterm labor in women with single risk factor. Search strategy: A PubMed, Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, Science Direct, Scopus, OVID, EMBASE, SID, Magiran and Google Scholar search (date last searched April 2016) without any time, language and location restriction was done. Inclusion criteria: All randomized clinical trials of singleton pregnancies with single risk factor (prior preterm labor without short cervical length or short cervical length without prior preterm labor) which were randomized to progesterone and control groups were included in our meta-analysis. Primary outcome: Our primary outcome was gestational age at delivery. Results: 13 studies (1259 subjects and 2653 control women) were included in the meta-analysis. Using random effect model showed that mean gestational age at delivery of progesterone group is 0.74 (0.41-1.06) month longer than that of control group with CI=95% which is significant statically. Conclusions: Progesterone therapy is an effective intervention for the prevention of preterm labor in women with single risk factor.
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- 2016
6. Electrochemical Performance of Graphene/Activated Carbon Based Electric Double Layer Supercapacitors
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Kefayat Ullah, Ick-Jun Kim, Sunhye Yang, Asghar Ali, Shu Ye, Won-Chun Oh, and Lei Zhu
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010302 applied physics ,Supercapacitor ,Graphene ,Chemistry ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,01 natural sciences ,law.invention ,Chemical engineering ,law ,0103 physical sciences ,medicine ,0210 nano-technology ,Activated carbon ,medicine.drug - Published
- 2016
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7. The Efficacy of Progesterone Therapy for the Prevention of Preterm Labor in Women with Mixed Risk-factors: A Systematic Review and Meta-analysis of Randomized Clinical Trials
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Elham Bahrami, Omid Barati, Sima Bahrami, Kefayat Chaman Ara, Mohammad Nabi Bahrami, Mahmood Moosazadeh, and Mohammad Amin Bahrami
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medicine.medical_specialty ,030219 obstetrics & reproductive medicine ,Preterm labor ,business.industry ,Progesterone therapy ,Alternative medicine ,law.invention ,03 medical and health sciences ,0302 clinical medicine ,Randomized controlled trial ,law ,Meta-analysis ,Internal medicine ,Physical therapy ,medicine ,030212 general & internal medicine ,business - Published
- 2018
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8. Enhanced visible light photocatalytic activity and hydrogen evolution through novel heterostructure AgI–FG–TiO2 nanocomposites
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Won-Chun Oh, Kefayat Ullah, Arif Ullah, Ali Aldalbahi, and Jin-Do Chung
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Graphene ,Scanning electron microscope ,Chemistry ,Process Chemistry and Technology ,Nanotechnology ,Chemical vapor deposition ,Catalysis ,law.invention ,symbols.namesake ,X-ray photoelectron spectroscopy ,Chemical engineering ,Transmission electron microscopy ,law ,Photocatalysis ,symbols ,Physical and Theoretical Chemistry ,Raman spectroscopy ,Ternary operation - Abstract
We report ternary AgI–FG–TiO 2 nanocomposites prepared through fast microwave technique. In this study we introduced a novel chemical vapor deposition (CVD) approach to functionalize powder graphene oxide (GO). The functionalize graphene (FG) sheets were then used for the attachment of AgI and TiO 2 nanoparticles to form a ternary composites. The prepared composites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopic analysis, X-ray diffraction (XRD), UV–vis absorbance spectra and UV–vis diffuse reflectance spectra (DRS). The photocatalytic activity for hydrogen evolution was greatly affected by the introduction of FG and ternary component in the system.
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- 2015
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9. CVD growth of large-area graphene over Cu foil by atmospheric pressure and its application in H2 evolution
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Lei Zhu, Won-Chun Oh, Kefayat Ullah, Shu Ye, Asghar Ali, and Won Kweon Jang
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Materials science ,Atmospheric pressure ,Scanning electron microscope ,Graphene ,Nanotechnology ,General Chemistry ,Condensed Matter Physics ,law.invention ,Crystal ,symbols.namesake ,Chemical engineering ,Transmission electron microscopy ,law ,symbols ,Photocatalysis ,General Materials Science ,Raman spectroscopy ,FOIL method - Abstract
This study reports that the atmospheric pressure chemical vapor deposition (CVD) growth of large area graphene (LAG) over a Cu foil. The obtained large area graphene was further decorated with TiO2 nanoparticles via ultrasonic method. The surface structure, crystal phase, and elemental identification of these obtained LAG/TiO2 composite were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis, and Raman spectra. The photocatalytic H2 evolution result illustrates Cu-LAG/TiO2 has been found to be a potential catalyst for conversion of solar energy to clean hydrogen energy under visible light-driven despite that the H2 evolution activity is not high enough in this stage.
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- 2015
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10. Preparation of highly expanded graphene with large surface area and its additional conductive effect for EDLC performance
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Won-Chun Oh, Ick-Jun Kim, Sunhye Yang, and Kefayat Ullah
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Supercapacitor ,Materials science ,Graphene ,Analytical chemistry ,Electrolyte ,Condensed Matter Physics ,Electrochemistry ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Dielectric spectroscopy ,law.invention ,symbols.namesake ,Chemical engineering ,law ,Electrode ,symbols ,Electrical and Electronic Engineering ,Cyclic voltammetry ,Raman spectroscopy - Abstract
Expanded graphene (EG) has been produced using fast oxidation/intercalation process. The as prepared EG were then used as conductive additive to study the electrochemical properties of activated carbon based electric double layered supercapacitors (EDLCs). The physiochemical properties of EG were studied using scanning electron microscopy, Raman spectroscopic techniques, atomic force microscopy and energy dispersive X-ray analysis. The electrochemical properties were studied using charge/discharge cyclic voltammetry and electrochemical impedance spectroscopy. All the electrochemical tests were carried out in 1 M, TEA BF4 in acetonitrile as a suitable electrolyte for our AC based supercapacitors. Electrochemical test reveals that EG greatly affect the conductivity of the ions through the AC/EG interface. The specific capacitance remains the same for smaller values of EG in the composites electrodes. These results also evident the optimum loading of graphene in the future graphene based EDLCs.
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- 2015
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11. A Facile Preparation of Graphene-Based MxSy Visible Light Driven Photocatalyst and Study of Photochemically Generating of Oxygen Species
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Lei Zhu, Won-Chun Oh, Shu Ye, Kefayat Ullah, Ze-Da Meng, and Sourav Sarkar
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Graphene ,Chemistry ,Inorganic chemistry ,Photochemistry ,Redox ,law.invention ,Catalysis ,Inorganic Chemistry ,law ,Photocatalysis ,Hydrothermal synthesis ,Carbazide ,Physical and Theoretical Chemistry ,Photodegradation ,Visible spectrum - Abstract
The as-synthesized graphene–MxSy (Sb2S3, MnS2, SnS) composites via a facile hydrothermal method efficiently catalyzed the photodegradation of methylene orange (MO) with high concentration in aqueous solutions under visible light irradiation. The generation of reactive oxygen species were detected through the oxidation reaction from 1,5-diphenyl carbazide (DPCI) to 1,5-diphenyl carbazone (DPCO). Based on the high photocatalytic activity, the graphene-SnS composite can be expected to be a practical visible light photocatalyst.
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- 2015
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12. Microwave-Assisted Synthesis of Pt-Graphene/TiO2 Nanocomposites and Their Efficiency in Assisting Hydrogen Evolution from Water in the Presence of Sacrificial Agents
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Kefayat Ullah, Won-Chun Oh, Lei Zhu, Shu Ye, and Asghar Ali
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Nanocomposite ,Materials science ,Graphene ,law ,General Materials Science ,Nanotechnology ,Hydrogen evolution ,Microwave assisted ,law.invention - Published
- 2015
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13. Modified hydrothermal synthesis and characterization of reduced graphene oxide-silver selenide nanocomposites with enhanced reactive oxygen species generation
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Won-Chun Oh, Shu Ye, Kefayat Ulla, Asghar Ali, Kwang Youn Cho, and Lei Zhu
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Nanocomposite ,Materials science ,Graphene ,Inorganic chemistry ,Oxide ,Nanoparticle ,General Medicine ,law.invention ,chemistry.chemical_compound ,Crystallinity ,chemistry ,Chemical engineering ,law ,Rhodamine B ,Photocatalysis ,Hydrothermal synthesis - Abstract
A visible-light photocatalyst containing Ag2Se and reduced graphene oxide (RGO) was synthesized by a facile sonochemical-assisted hydrothermal method. X-ray diffraction, scanning electron microscopy with energy-dispersive X-ray analysis, and ultraviolet-visible diffuse reflectance spectroscopy results indicated that the RGO-Ag2Se nanocomposite contained small crystalline Ag2Se nanoparticles dispersed over graphene nanosheets and absorbed visible light. The high crystallinity of the nanoparticles increased photocatalytic activity by facilitating charge transport. N2 adsorption-desorption measurements revealed that the RGO-Ag2Se nanocomposite contained numerous pores with an average diameter of 9 nm, which should allow reactant molecules to readily access the Ag2Se nanoparticles. The RGO-Ag2Se nanocomposite exhibited higher photocatalytic activity than bulk Ag2Se nanoparticles to degrade organic pollutant rhodamine B and industrial dye Texbrite BA-L under visible-light irradiation (γ > 420 nm). The generation of reactive oxygen species in RGO-Ag2Se was evaluated through its ability to oxidize 1,5-diphenylcarbazide to 1,5-diphenylcarbazone. The small size of the Ag2Se nanoparticles in RGO-Ag2Se was related to the use of ultrasonication during their formation, revealing that this approach is attractive to form porous RGO-Ag2Se materials with high photocatalytic activity under visible light.
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- 2015
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14. A green and direct synthesis of photosensitized CoS2–graphene/TiO2 hybrid with high photocatalytic performance
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Shu Ye, Kefayat Ullah, Won-Chun Oh, Ze-Da Meng, Sun-Bok Jo, and Lei Zhu
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Graphene ,Chemistry ,Scanning electron microscope ,General Chemical Engineering ,Photochemistry ,law.invention ,chemistry.chemical_compound ,law ,Transmission electron microscopy ,Photocatalysis ,Fourier transform infrared spectroscopy ,Methylene blue ,BET theory ,Visible spectrum - Abstract
CoS2, CoS2–graphene and CoS2–graphene/TiO2 composite was synthesized by a facile sonochemical and hydrothermal method. X-ray diffraction, scanning electron microscopy with energy-dispersive X-ray analysis, transmission electron microscopy, FT-IR, UV–vis and BET surface area was calculated by nitrogen adsorption were used. The FT-IR results illuminated that CoS2 and TiO2 band transfers electrons to graphene with functional groups attached. UV–vis patterns indicated that CoS2–graphene/TiO2 have good photoinduction effects in visible light region. The photocatalytic activity of sample was evaluated by measuring the degradation of organic pollutants such as methylene blue (MB), and industrial dyes such as Texbrite BA-L (TBA) under visible light.
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- 2015
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15. Carbonaceous Materials-Based Electric Double Layer Capacitors with Improved Electrochemical Performance
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Sunhye Yang, Ick-Jun Kim, Kefayat Ulla, Shu Ye, Changzhou Yuan, Won-Chun Oh, Lei Zhu, and Asghar Ali
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Capacitor ,Chemistry ,business.industry ,law ,Optoelectronics ,General Chemistry ,business ,Electrochemistry ,law.invention - Published
- 2015
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16. Enhanced Physical and Thermal Performance of Expanded Graphite-Based Heat Sink for LED Radiator
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Asghar Ali, Won-Chun Oh, Shu Ye, Kefayat Ullah, Hamid Ullah, and Lei Zhu
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Chemistry ,law ,Thermal ,General Chemistry ,Graphite ,Heat sink ,Composite material ,Radiator ,law.invention - Published
- 2015
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17. Synergistic effect of PtSe2 and graphene sheets supported by TiO2 as cocatalysts synthesized via microwave techniques for improved photocatalytic activity
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Zhu Lei, Shu Ye, Kwang-Yeon Cho, Won-Chun Oh, and Kefayat Ullah
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Nanocomposite ,Materials science ,Scanning electron microscope ,Graphene ,Analytical chemistry ,Catalysis ,law.invention ,chemistry.chemical_compound ,symbols.namesake ,chemistry ,X-ray photoelectron spectroscopy ,Chemical engineering ,Transmission electron microscopy ,law ,Rhodamine B ,Photocatalysis ,symbols ,Raman spectroscopy - Abstract
Here we report a new composite material consisting of TiO2 nanoparticles grown in the presence of a layered PtSe2/graphene hybrid as a high-performance photocatalytic material. The heterogeneous PtSe2–graphene/TiO2 nanocomposites were successfully synthesized through a facile and fast microwave-assisted method. The prepared composites were characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM), Raman spectroscopic analysis, X-ray photoelectron spectroscopy (XPS), and UV-vis absorbance spectra and UV-vis diffuse reflectance spectra (DRS) analyses were obtained. The catalytic behavior was investigated through the decomposition of rhodamine B (Rh. B) as a standard dye and Texbrite MST-L as an industrial dye. This extraordinary photocatalytic activity arises from the positive synergetic effect between the PtSe2 and graphene components in this heterogeneous photocatalyst. In this study the graphene behaves as an electron transfer agent, collector, contributor and a source of active adsorption sites. The optical properties were also observed to be affected by the different weight% of graphene in the composites by observing their respective band gaps from DRS spectra.
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- 2015
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18. Additional Materials Effect for Improved Electrochemical Performance of Activated Carbon Fiber Based Electric Double Layer Capacitors
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Sang-Gil Kim, Kefayat Ullah, Byung-Jun Lee, Young-Re Kim, Eun-Hye Yoon, Lei Zhu, Won-Chun Oh, Bum-Soo Kim, and Shu Ye
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Supercapacitor ,business.industry ,Chemistry ,Nanotechnology ,General Chemistry ,Electrochemistry ,law.invention ,Capacitor ,law ,medicine ,Optoelectronics ,Fiber ,business ,Activated carbon ,medicine.drug - Published
- 2015
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19. Microwave synthesis of a CoSe2/graphene–TiO2 heterostructure for improved hydrogen evolution from aqueous solutions in the presence of sacrificial agents
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Won-Chun Oh, Asghar Ali, Shu Ye, Zhu Lei, and Kefayat Ullah
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Materials science ,Scanning electron microscope ,Band gap ,Graphene ,General Chemical Engineering ,Analytical chemistry ,Heterojunction ,General Chemistry ,law.invention ,symbols.namesake ,Transmission electron microscopy ,law ,symbols ,Photocatalysis ,Raman spectroscopy ,Ternary operation - Abstract
A heterogeneous material consisting of a tube type TiO2 was grown in the presence of a CoSe2/graphene hybrid, as a high-performance photocatalyst material, through a fast microwave-assisted technique. The prepared composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopic analysis, UV-vis absorbance spectra and UV-vis diffuse reflectance spectra (DRS) analysis. The hydrogen evolution rate for ternary composites was found to be markedly high compared to bare TiO2 and binary CoSe2/graphene composites. This extraordinary photocatalytic activity for hydrogen evolution arises from the positive synergistic effect between the CoSe2 and graphene components in our heterogeneous system. The optical properties were also found to be affected by the different weight% of graphene in the composites by observing their respective band gaps from the DRS spectra.
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- 2015
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20. Thermal and Physical Performance of Heat Sink for Light-Emitting Diode Improved with Expanded Graphite
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Won-Chun Oh, Shu Ye, Asghar Ali, Kefayat Ullah, Lei Zhu, and Chang Sung Lim
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business.industry ,law ,Chemistry ,Physical performance ,Thermal ,Optoelectronics ,General Chemistry ,Graphite ,Heat sink ,business ,Light-emitting diode ,law.invention - Published
- 2015
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21. Rhodamine B degradation and reactive oxygen species generation by a ZnSe-graphene/TiO2 sonocatalyst
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Sun-Bok Jo, Kefayat Ullah, Lei Zhu, Shu Ye, and Won-Chun Oh
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Reaction mechanism ,Chemistry ,Graphene ,General Medicine ,Photochemistry ,Catalysis ,law.invention ,chemistry.chemical_compound ,Adsorption ,law ,Rhodamine B ,Degradation (geology) ,Zinc selenide ,Carbazide - Abstract
Nanostructured ZnSe-graphene/TiO 2 was synthesized by a hydrothermal-assisted approach. ZnSe-graphene/TiO 2 exhibited favorable adsorption of rhodamine B, a wide wavelength absorption range, and efficient charge separation. Reactive oxygen species were generated by the oxidation of 1,5-diphenyl carbazide to 1,5-diphenyl carbazone. The sonocatalytic reaction mechanism was proposed. These findings potentially broaden the applications of sonocatalytic technologies.
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- 2014
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22. Modified hydrothermal fabrication of a CoS2–graphene hybrid with improved photocatalytic performance
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Shu Ye, Won-Chun Oh, Lei Zhu, Ze-Da Meng, and Kefayat Ullah
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Materials science ,Diffuse reflectance infrared fourier transform ,Scanning electron microscope ,Graphene ,Mechanical Engineering ,Condensed Matter Physics ,Photochemistry ,law.invention ,Photoinduced charge separation ,Mechanics of Materials ,law ,Photocatalysis ,General Materials Science ,Photodegradation ,Hybrid material ,Visible spectrum - Abstract
CoS 2 and a CoS 2 –graphene composite were synthesized via a facile sonochemical and hydrothermal method. As-prepared samples were characterized by X-ray diffraction, scanning electron microscopy with energy-dispersive X-ray analysis, transmission electron microscopy, and UV-vis diffuse reflectance spectroscopy. The CoS 2 –graphene composites exhibited high dye adsorption, extended light absorption, and efficient charge separation properties. Hence, for photodegradation of methylene blue (MB), significant enhancement of the reaction rate was observed for CoS 2 –graphene compared to pure CoS 2 . The high activity can be attributed to positive synergetic effects between CoS 2 and graphene. The excellent photoinduced charge separation and observed red shift make these hybrid materials potential candidates for the development of high-performance next-generation photocatalyst materials.
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- 2014
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23. Novel PbSe/Graphene Nanocomposites Synthesized With Ultrasonic Assisted Method and their Enhanced Photocatalytic Activity
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Nikam Vikram, Shu Ye, Kefayat Ullah, Ze-Da Meng, Won-Chun Oh, Kwang-Youn Cho, and Lei Zhu
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Nanocomposite ,Scanning electron microscope ,Chemistry ,Graphene ,Composite number ,Nanotechnology ,law.invention ,Inorganic Chemistry ,symbols.namesake ,chemistry.chemical_compound ,Chemical engineering ,law ,Transmission electron microscopy ,Photocatalysis ,symbols ,Rhodamine B ,Physical and Theoretical Chemistry ,Raman spectroscopy - Abstract
The authors report novel material PbSe/graphene nanocomposite synthesis via facile ultrasonic assisted method. The structural and physicochemical properties of PbSe/graphene composite are further characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) with an energy-dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), and Raman spectroscopy analysis. The photocatalytic activities were investigated by the degradation of methylene blue and rhodamine B as a standard dye. This study suggests that the as-prepared PbSe/graphene nanocomposite can be utilized as an efficient photocatalyst material.
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- 2014
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24. Degradation of Organic Dyes by CdSe Decorated Graphene Nanocomposite in Dark Ambiance
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Won-Chun Oh, Goutam Mukhopadhyay, Shu Ye, Kefayat Ullah, Jo Sun-Bok, and Lei Zhu
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Materials science ,Nanocomposite ,Cadmium selenide ,Graphene ,Scanning electron microscope ,Organic Chemistry ,Analytical chemistry ,Atomic and Molecular Physics, and Optics ,law.invention ,chemistry.chemical_compound ,Ultraviolet visible spectroscopy ,chemistry ,Chemical engineering ,law ,Methyl orange ,Rhodamine B ,General Materials Science ,Physical and Theoretical Chemistry ,Visible spectrum - Abstract
Cadmium selenide (CdSe)-graphene composite materials were synthesized via a facile hydrothermal method and the intriguing catalytic activity of the composites was investigated using organic dyes in complete absence of irradiation source (UV or visible light). The catalytic activity of CdSe-graphene composites was measured using methyl orange (MO) and rhodamine B (Rh.B) dye solutions. The characterizations of composites were studied by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and with energy dispersive X-ray (EDX). The catalytic degradation was measured by analyzing the decrease in absorbance spectra in UV-Vis spectroscopy. The degradation of the organic dyes in absence of any irradiation was illustrated by the degradation property of CdSe and charge mobility. The catalytic activity after repeated use of the composites was also tested in order to investigate the stability of CdSe-graphene composites.
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- 2014
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25. Ultrasonic-Assisted Synthesis of Pd-MWCNT/TiO2Catalysts and Its Application in the Photodegradation of Reactive Black B
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Won-Chun Oh, Kefayat Ullah, Shu Ye, and Lei Zhu
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Materials science ,Absorption spectroscopy ,medicine.diagnostic_test ,Scanning electron microscope ,Organic Chemistry ,Analytical chemistry ,Carbon nanotube ,Atomic and Molecular Physics, and Optics ,law.invention ,Ultraviolet visible spectroscopy ,Transmission electron microscopy ,law ,Spectrophotometry ,Photocatalysis ,medicine ,General Materials Science ,Physical and Theoretical Chemistry ,Photodegradation ,Nuclear chemistry - Abstract
MWCNT-TiO2 and Pd-MWCNT/TiO2 composites were prepared by a high-intensity ultrasonic method using a lower temperature (80oC), and their high photocatalytic activity was evaluated by the degradation of reactive black B solutions (RBB) under visible light. The surface structure, crystal phase, and elemental identification of these composites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX) spectroscopy, and UV–vis absorption spectra (UV–vis), respectively. The degradation of RBB solution was determined using UV–vis spectrophotometry. An increase in photocatalytic activity was observed and it may attribute to increase of the photo-absorption effect by the multi-walled carbon nanotubes (MWCNT) and the cooperative effect of the Pd element.
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- 2014
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26. Photocatalytic properties under visible light with graphene based platinium selenide nanocomposites synthesized by microwave assisted method
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Won-Chun Oh, Ze-Da Meng, Lei Zhu, Sourav Sarkar, Kefayat Ullah, and Shu Ye
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Materials science ,Graphene ,Scanning electron microscope ,Mechanical Engineering ,Analytical chemistry ,Condensed Matter Physics ,law.invention ,chemistry.chemical_compound ,symbols.namesake ,chemistry ,Chemical engineering ,Mechanics of Materials ,law ,Transmission electron microscopy ,Selenide ,Photocatalysis ,symbols ,General Materials Science ,Energy source ,Raman spectroscopy ,Visible spectrum - Abstract
We report a simple and effective route to synthesize graphene based platinium selenide nanocomposites by facile and fast microwave assisted techniques. The “as-prepared” composites are further characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), Raman spectroscopic analysis, UV–vis absorbance spectra analysis and UV–vis diffuse reflectance spectra (DRS). The photocatalytic activities were investigated by the degradation of methylene blue and rhudamine B as standard dye. This result gives a promising development towards graphene based efficient photocatalyst that employed visible light as an energy source.
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- 2014
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27. Sonophotocatalytic Performance of Bi2Se3-Graphene/TiO2Hybrid Nanomaterials Synthesized with a Microwave-assisted Method
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Won-Chun Oh, Sun-Bok Jo, Shu Ye, Lei Zhu, and Kefayat Ullah
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Materials science ,Nanocomposite ,Graphene ,Nanotechnology ,Nanomaterials ,law.invention ,Nanocrystal ,Absorption edge ,Chemical engineering ,law ,Ceramics and Composites ,Photocatalysis ,Nanosheet ,Visible spectrum - Abstract
This paper introduces a microwave-assisted synthesis method to prepare hybrid Bi₂Se₃-GR/TiO₂ nanocomposites, which exhibit superior properties over single component materials. The as-prepared composites were characterized by XRD, UV-vis absorbance spectra, SEM,TEM, EDX, and BET analyses, revealing uniform covering of the graphene nanosheet with Bi₂Se₃ and TiO₂ nanocrystals. For visible light photocatalysis of Rh.B, a significant enhancement in the reaction rate was consequently observed with Bi₂Se₃-GR/TiO₂ composites. The degradation rate(kapp) obtained for sonophotocatalysis was 6.8× 10-3 min-1, roughly 2.2 times better than that of VL photocatalysis under higher concentrations of Rh.B. The sonophotocatalysis was faster due to greater formation of reactive radicals as well as an increase of the active surface area of the Bi₂Se₃-GR/TiO₂ composites. The high activity is attributed to the synergetic effects of high charge mobility and red shift of the absorption edge of Bi₂Se₃-GR/TiO₂.
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- 2014
- Full Text
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28. Synthesis and characterization of novel PbS–graphene/TiO2 composite with enhanced photocatalytic activity
- Author
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Won-Chun Oh, Ze-Da Meng, Lei Zhu, Kefayat Ullah, and Shu Ye
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Materials science ,Graphene ,Scanning electron microscope ,General Chemical Engineering ,Composite number ,Nanotechnology ,law.invention ,symbols.namesake ,Chemical engineering ,Photoinduced charge separation ,Transmission electron microscopy ,law ,Photocatalysis ,symbols ,Raman spectroscopy ,Sol-gel - Abstract
In this study novel material PbS–graphene/TiO2 composites were prepared by sol–gel method. The “as-prepared” composites were characterized by 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) and Raman spectroscopic analysis. The photocatalytic activities were investigated by the degradation of methylene blue (MB) as a standard dye. We observed that coupling of PbS with TiO2 extends the photoresponse to visible region. This revealed that the excellent photoinduced charge separation abilities and transport properties of graphene make these hybrids as potential candidates for developing high-performance next-generation devices.
- Published
- 2014
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- View/download PDF
29. Noble metal doped graphene nanocomposites and its study of photocatalytic hydrogen evolution
- Author
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Won-Chun Oh, Sun Bok Jo, Lei Zhu, Kwang-Youn Cho, Won Kweon Jang, Kefayat Ullah, and Shu Ye
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Materials science ,Nanocomposite ,Graphene ,Scanning electron microscope ,chemistry.chemical_element ,Nanotechnology ,General Chemistry ,engineering.material ,Condensed Matter Physics ,law.invention ,chemistry ,Chemical engineering ,X-ray photoelectron spectroscopy ,law ,Transmission electron microscopy ,engineering ,General Materials Science ,Noble metal ,Platinum ,Nanosheet - Abstract
This work reports the deposition of platinum (Pt) nanoparticles on the surface of graphene nanosheet by a simple approach, using a microwave-assisted method. The photocatalytic activity has been investigated for hydrogen evolution. The hydrogen evolutions were attributed to graphene, due to its high photoelectron transport properties, and the Pt nanoparticles attached on the surface of graphene sheet, which act as reaction centers for H2 evolution. The “as-prepared” composites were characterized by Brunauer Emmett Teller (BET) surface area measurement, X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV–vis diffuse reflectance spectra (DRS). This work highlights the potential application of graphene-based materials in the field of energy conversion.
- Published
- 2014
- Full Text
- View/download PDF
30. Synthesis and characterization of novel PtSe2/graphene nanocomposites and its visible light driven catalytic properties
- Author
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Shu Ye, Sourav Sarkar, Kefayat Ullah, Ze-Da Meng, Won-Chun Oh, and Lei Zhu
- Subjects
Nanocomposite ,Materials science ,Graphene ,Mechanical Engineering ,Analytical chemistry ,law.invention ,symbols.namesake ,Chemical engineering ,Mechanics of Materials ,law ,Transmission electron microscopy ,Photocatalysis ,symbols ,General Materials Science ,Photodegradation ,Energy source ,Raman spectroscopy ,Visible spectrum - Abstract
In this study, we report a novel PtSe2/graphene nanocomposite by facile ultrasonic-assisted techniques. The “as-prepared” nanocomposites were further characterized by various techniques such as X-ray diffraction, scanning electron microscopy with an energy dispersive X-ray analysis, transmission electron microscopy, UV–Vis absorbance spectra analysis, diffuse reflectance analysis, and Raman spectroscopic analysis. The photocatalytic activities of the composites were investigated by the degradation of rhudamine B and methylene blue as a standard dyes. The photodegradation rates of organic dyes by the nanocomposites are found to be markedly high. This study suggests that the as-prepared PtSe2/graphene composite can be utilized as highly efficient photocatalyst materials that employed visible light as an energy source.
- Published
- 2014
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31. Microwave assisted synthesis of a noble metal-graphene hybrid photocatalyst for high efficient decomposition of organic dyes under visible light
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Won-Chun Oh, Shu Ye, Ze-Da Meng, Sourav Sarkar, Lei Zhu, and Kefayat Ullah
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Nanocomposite ,Materials science ,Graphene ,Scanning electron microscope ,Mechanical Engineering ,Condensed Matter Physics ,Photochemistry ,law.invention ,symbols.namesake ,chemistry.chemical_compound ,chemistry ,Mechanics of Materials ,law ,Photocatalysis ,symbols ,Rhodamine B ,General Materials Science ,Energy source ,Raman spectroscopy ,Visible spectrum - Abstract
We report fast and facile synthesis of Pt/graphene nanocomposite via microwave assisted techniques. The “as-prepared” composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) with an energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), UV–vis absorbance spectra analysis, diffuse reflectance spectra (DRS) analysis and Raman spectroscopic analysis. The visible light photo catalytic activities of Pt/graphene nanocomposite were tested by rhodamine B (Rh.B) and methylene blue (MB) as a standard model dyes. These analysis provide a promising development toward graphene based high efficient photocatalyst under visible light as an energy source.
- Published
- 2014
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32. Progress in Design and Fabrication of Novel Graphene-Based Semiconductor Photocatalysts
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Kefayat Ullah, Lei Zhu, Won-Chun Oh, Shu Ye, and Asghar Ali
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Fabrication ,Semiconductor ,Chemistry ,Graphene ,law ,business.industry ,Nanotechnology ,General Chemistry ,business ,law.invention - Published
- 2014
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- View/download PDF
33. Sonophotocatalytic Performance of Ag2Se-Graphene Hybrid Nanomaterials Synthesized by Hydrothermal Method
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Lei Zhu, Won-Chun Oh, Shu Ye, Kwang Youn Cho, and Kefayat Ullah
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Graphene ,law ,Chemistry ,Nanotechnology ,General Chemistry ,Hydrothermal circulation ,law.invention ,Nanomaterials - Published
- 2015
- Full Text
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34. Preparation of novel CdS-graphene/TiO2 composites with high photocatalytic activity for methylene blue dye under visible light
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Won-Chun Oh, Chong-Yeon Park, Trisha Ghosh, K Y Cho, Nikam Vikram, and U Kefayat
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Materials science ,Scanning electron microscope ,Graphene ,Kinetics ,Photochemistry ,law.invention ,chemistry.chemical_compound ,chemistry ,Mechanics of Materials ,Transmission electron microscopy ,law ,Photocatalysis ,General Materials Science ,Composite material ,Photodegradation ,Methylene blue ,Visible spectrum - Abstract
In this study, CdS combined graphene/TiO2 (CdS-graphene/TiO2) composites were prepared by a sol–gel method to improve on the photocatalytic performance of TiO2. These composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and transmission electron microscopy (TEM). The photocatalytic activities were examined by the degradation of methylene blue (MB) under visible light irradiation. The photodegradation rate of MB under visible light irradiation reached 90·1% during 150 min. The kinetics of MB degradation were plotted alongside the values calculated from the Langmuir–Hinshelwood equation. 0·1 CGT sample showed the best photocatalytic activity, which was attributed to a cooperative reaction between the increase of photo-absorption effect by graphene and photocatalytic effect by CdS.
- Published
- 2013
- Full Text
- View/download PDF
35. A facile and fast synthesis of novel composite Pt–graphene/TiO2 with enhanced photocatalytic activity under UV/Visible light
- Author
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Lei Zhu, Won-Chun Oh, Shu Ye, Ze-Da Meng, Kefayat Ullah, and Qian Sun
- Subjects
Materials science ,Graphene ,Scanning electron microscope ,General Chemical Engineering ,Analytical chemistry ,General Chemistry ,Photochemistry ,Industrial and Manufacturing Engineering ,law.invention ,chemistry.chemical_compound ,chemistry ,Photoinduced charge separation ,law ,Photocatalysis ,Rhodamine B ,Environmental Chemistry ,Photodegradation ,Hybrid material ,Visible spectrum - Abstract
In this study, novel material Pt–graphene/TiO2 nanocomposites were prepared by facile and fast microwave assisted method. The “as-prepared” composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) with an energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM) and UV–Visible absorbance spectra analysis. UV–Visible diffuse spectra (DRS) were obtained by using a scan UV–Visible spectrophotometer equipped with an integrating sphere assembly. The photocatalytic activities were investigated by the degradation of rhodamine B (Rh.B) as a standard dye. The photodegradation rate of Rh.B under UV/Visible light was found markedly high with increasing wt% of graphene in Pt–graphene/TiO2 nanocomposites. This revealed that the excellent photoinduced charge separation abilities and observed red shift in these hybrid semiconductors, transport properties of graphene make these hybrid materials as potential candidates for developing high-performance and next-generation photocatalyst materials.
- Published
- 2013
- Full Text
- View/download PDF
36. Enhanced visible light photocatalytic activity of Ag2S-graphene/TiO2 nanocomposites made by sonochemical synthesis
- Author
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Kefayat Ullah, Ze-Da Meng, Shu Ye, Lei Zhu, Qian Sun, and Won-Chun Oh
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Materials science ,medicine.diagnostic_test ,Scanning electron microscope ,Graphene ,General Medicine ,Photochemistry ,law.invention ,chemistry.chemical_compound ,chemistry ,Absorption edge ,Transmission electron microscopy ,law ,Spectrophotometry ,Rhodamine B ,medicine ,Photodegradation ,Visible spectrum - Abstract
Ag2S‐graphene/TiO2 composites were synthesized by a facile sonochemical method. The products were characterized by X‐ray diffraction, scanning electron microscopy, energy dispersive X‐ray spectroscopy, transmission electron microscopy, and UV‐Vis diffuse reflectance spectrophotometry. During the synthesis reaction, the reduction of graphene oxide and loading of Ag2S and TiO2 particles were achieved. The Ag2S‐graphene/TiO2 composites possessed a large adsorption capacity for dyes, an extended light absorption range, and efficient charge separation properties. Hence, in the photodegradation of rhodamine B, a significant enhancement in the reaction rate was observed with the Ag2S‐graphene/TiO2 composites as compared to pure TiO2. The generation of reactive oxygen species was detected by the oxidation of 1,5‐diphenyl carbazide to 1,5‐diphenyl carbazone. The high activity was attributed to the synergetic effects of high charge mobility and the red shift in the absorption edge of the Ag2S‐graphene/TiO2 composites.
- Published
- 2013
- Full Text
- View/download PDF
37. High photonic effect of organic dye degradation by CdSe–graphene–TiO2 particles
- Author
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Won-Chun Oh, Ze-Da Meng, Trisha Ghosh, Vikram Nikam, Chong-Yeon Park, Kwang-Youn Cho, and Kefayat Ullah
- Subjects
Materials science ,Cadmium selenide ,Graphene ,Scanning electron microscope ,General Chemical Engineering ,Inorganic chemistry ,technology, industry, and agriculture ,Titanium oxide ,law.invention ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Transmission electron microscopy ,law ,Photocatalysis ,Rhodamine B ,Methyl orange - Abstract
Photocatalytic activity of CdSe (cadmium selenide) decorated graphene composites coupled with TiO 2 (titanium oxide) was investigated with organic dye solutions. The characterizations of composites were studied by X-ray diffraction (XRD), energy dispersive X-ray (EDX), scanning electron microscope (SEM), and with transmission electron microscope (TEM). The degradation of methyl orange (MO) and rhodamine B (RhB) was observed by measuring the decrease in the concentration by UV spectrophotometer. The synergistic effect of graphene on CdSe and TiO 2 was demonstrated by comparative study. The composites were tested for recyclability, investigating the stability of CdSe–graphene/TiO 2 composites.
- Published
- 2013
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38. Preparation of CuS-graphene oxide/TiO2 composites designed for high photonic effect and photocatalytic activity under visible light
- Author
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Ullah Kefayat, Nikam Vikram, Trisha Ghosh, Ze-Da Meng, Chong-Yeon Park, and Won-Chun Oh
- Subjects
Materials science ,Graphene ,Scanning electron microscope ,Oxide ,General Medicine ,law.invention ,chemistry.chemical_compound ,chemistry ,law ,Transmission electron microscopy ,Photocatalysis ,Irradiation ,Composite material ,Photodegradation ,Visible spectrum - Abstract
CuS-graphene oxide/TiO2 composites were prepared using a sol-gel method to improve the photocatalytic performance of the photocatalyst. The composites were characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, and transmission electron microscopy. The photocatalytic activities were examined by the degradation of methylene blue (MB) under visible-light irradiation. The photodegradation of MB under visible-light irradiation reached 90.1% after 120 min. The kinetics of MB degradation was plotted alongside the values calculated from the Langmuir-Hinshelwood equation. The CuS-graphene oxide/TiO2 sample prepared using 0.2 mol of TiO2 showed the best photocatalytic activity. This was attributed to a cooperative reaction as a result of increased photoabsorption by graphene oxide and an increased photocatalytic effect by CuS.
- Published
- 2013
- Full Text
- View/download PDF
39. Graphene oxide based CdSe photocatalysts: Synthesis, characterization and comparative photocatalytic efficiency of rhodamine B and industrial dye
- Author
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Kefayat Ullah, Won-Chun Oh, Trisha Ghosh, Jeong-Ho Lee, Chong-Yeon Park, Ze-Da Meng, and Vikram Nikam
- Subjects
Materials science ,Cadmium selenide ,Scanning electron microscope ,Graphene ,Mechanical Engineering ,Analytical chemistry ,Condensed Matter Physics ,law.invention ,Absorbance ,chemistry.chemical_compound ,chemistry ,Mechanics of Materials ,Transmission electron microscopy ,law ,Rhodamine B ,Photocatalysis ,Hydrothermal synthesis ,General Materials Science ,Nuclear chemistry - Abstract
CdSe–graphene composites were prepared using simple “hydrothermal method” where the graphene surface was modified using different molar solutions of cadmium selenide (CdSe) in aqueous media. The characterization of CdSe–graphene composites were studied by X-ray diffraction (XRD), energy dispersive X-ray (EDX), scanning electron microscope (SEM), and with transmission electron microscope (TEM). The catalytic activities of CdSe-composites were evaluated by degradation of rhodamine B (RhB) and commercial industrial dye “Texbrite MST-L (TXT-MST)” with fixed concentration. The degradation was observed by the decrease in the absorbance peak studied by UV spectrophotometer. The decrease in the dye concentration indicated catalytic degradation effect by CdSe–graphene composites.
- Published
- 2013
- Full Text
- View/download PDF
40. Vaginal progesterone vs intramuscular 17α-hydroxyprogesterone caproate for prevention of recurrent spontaneous preterm birth in singleton gestations: systematic review and meta-analysis of randomized controlled trials
- Author
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Andrew Elimian, Mohammad Amin Bahrami, Kefayat Chaman-Ara, Elham Bahrami, Adeeb Khalifeh, Vincenzo Berghella, Gabriele Saccone, Saccone, G., Khalifeh, A., Elimian, A., Bahrami, E., Chaman-Ara, K., Bahrami, M. A., and Berghella, V.
- Subjects
medicine.medical_specialty ,Radiology, Nuclear Medicine and Imaging ,Intensive Care Unit ,ultrasound cervical length ,Injections, Intramuscular ,Drug Administration Schedule ,law.invention ,transvaginal ultrasound ,03 medical and health sciences ,0302 clinical medicine ,Patient Admission ,Randomized controlled trial ,prevention ,law ,Hydroxyprogesterone ,Pregnancy ,17 alpha-Hydroxyprogesterone Caproate ,medicine ,Hydroxyprogesterones ,Humans ,030212 general & internal medicine ,Progesterone ,Randomized Controlled Trials as Topic ,Gynecology ,030219 obstetrics & reproductive medicine ,Radiological and Ultrasound Technology ,business.industry ,Obstetrics ,prematurity ,Obstetrics and Gynecology ,17α-Hydroxyprogesterone ,General Medicine ,Administration, Intravaginal ,Intensive Care Units ,Transvaginal ultrasound ,Reproductive Medicine ,Meta-analysis ,Gestation ,Premature Birth ,Female ,business ,medicine.drug ,Human - Abstract
Objective Randomized controlled trials (RCTs) have recently compared intramuscular 17α-hydroxyprogesterone caproate (17-OHPC) with vaginal progesterone for reducing the risk of spontaneous preterm birth (SPTB) in singleton gestations with prior SPTB. The aim of this systematic review and meta-analysis was to evaluate the efficacy of vaginal progesterone compared with 17-OHPC in prevention of SPTB in singleton gestations with prior SPTB. Methods Searches of electronic databases were performed to identify all RCTs of asymptomatic singleton gestations with prior SPTB that were randomized to prophylactic treatment with either vaginal progesterone (intervention group) or intramuscular 17-OHPC (comparison group). No restrictions for language or geographic location were applied. The primary outcome was SPTB < 34 weeks. Secondary outcomes were SPTB < 37 weeks, < 32 weeks, < 28 weeks and < 24 weeks, maternal adverse drug reaction and neonatal outcomes. The summary measures were reported as relative risk (RR) with 95% CI. Risk of bias for each included study was assessed. Results Three RCTs (680 women) were included. The mean gestational age at randomization was about 16 weeks. Women were given progesterone until 36 weeks or delivery. Regarding vaginal progesterone, one study used 90 mg gel daily, one used 100 mg suppository daily and one used 200 mg suppository daily. All included RCTs used 250 mg intramuscular 17-OHPC weekly in the comparison group. Women who received vaginal progesterone had significantly lower rates of SPTB < 34 weeks (17.5% vs 25.0%; RR, 0.71 (95% CI, 0.53–0.95); low quality of evidence) and < 32 weeks (8.9% vs 14.5%; RR, 0.62 (95% CI, 0.40–0.94); low quality of evidence) compared with women who received 17-OHPC. There were no significant differences in the rates of SPTB < 37 weeks, < 28 weeks and < 24 weeks. The rate of women who reported adverse drug reactions was significantly lower in the vaginal progesterone group compared with the 17-OHPC group (7.1% vs 13.2%; RR, 0.53 (95% CI, 0.31–0.91); very low quality of evidence). Regarding neonatal outcomes, vaginal progesterone was associated with a lower rate of neonatal intensive care unit admission compared with 17-OHPC (18.7% vs 23.5%; RR, 0.63 (95% CI, 0.47–0.83); low quality of evidence). For the comparison of 17-OHPC vs vaginal progesterone, the quality of evidence was downgraded for all outcomes by at least one degree due to imprecision (the optimal information size was not reached) and by at least one degree due to indirectness (different interventions). Conclusions Daily vaginal progesterone (either suppository or gel) started at about 16 weeks' gestation is a reasonable, if not better, alternative to weekly 17-OHPC injection for prevention of SPTB in women with singleton gestations and prior SPTB. However, the quality level of the summary estimates was low or very low as assessed by GRADE, indicating that the true effect may be, or is likely to be, substantially different from the estimate of the effect. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd. Comparacion entre la progesterona vaginal y el 17α-hidroxiprogesterona caproato intramuscular para la prevencion del parto pretermino espontaneo recurrente en embarazos con feto unico: revision sistematica y metaanalisis de ensayos controlados aleatorios RESUMEN Objetivo Recientemente se han realizado varios ensayos controlados aleatorios (ECA) que comparaban el caproato de 17α-hidroxiprogesterona (17-OHPC, por sus siglas en ingles) por via intramuscular con la progesterona por via vaginal para la reduccion del riesgo de parto pretermino espontaneo (PPTE) en embarazos con feto unico de gestantes con historial de PPTE. El objetivo de esta revision sistematica y metaanalisis fue evaluar la eficacia de la progesterona vaginal en comparacion con la 17-OHPC en la prevencion de embarazos con feto unico de gestantes con historial de PPTE. Metodos Se realizaron busquedas en bases de datos electronicas para identificar todos los ECA con embarazos de feto unico asintomaticos con historial de PPTE antes de ser asignados al azar a un tratamiento profilactico, ya fuera con progesterona vaginal (grupo de intervencion) o con 17-OHPC intramuscular (grupo de control). No se aplicaron restricciones respecto al idioma o la ubicacion geografica. El resultado primario fue PPTE < 34 semanas. Los resultados secundarios fueron PPTE
- Published
- 2016
41. Ag2Se-Graphene/TiO2Nanocomposites, Sonochemical Synthesis and Enhanced Photocatalytic Properties Under Visible Light
- Author
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Won-Chun Oh, Ze-Da Meng, Kefayat Ullah, Lei Zhu, Vikram Nikam, Trisha Ghosh, and Chong-Yeon Park
- Subjects
Materials science ,Graphene ,Scanning electron microscope ,Analytical chemistry ,General Chemistry ,law.invention ,chemistry.chemical_compound ,chemistry ,Absorption edge ,Chemical engineering ,Transmission electron microscopy ,law ,Rhodamine B ,Photocatalysis ,Photodegradation ,Visible spectrum - Abstract
Ag2Se-Graphene/TiO2 composite was synthesized by a facile sonochemical method. The as-prepared products were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM) and UV-vis diffuse reflectance spectrophotometer. During the reaction, both of the reduction of graphene oxide and loading of Ag2Se and TiO2 particles were achieved. The as-prepared Ag2Se-Graphene/TiO2 composites possessed great adsorptivity of dyes, extended light absorption range, and efficient charge separation properties simultaneously. Hence, in the photodegradation of rhodamine B (Rh.B), a significant enhancement in the reaction rate was observed with Ag2Se-Graphene/TiO2 composites, compared to the pure TiO2. The high activity can be attributed to the synergetic effects of high charge mobility, and red shift in absorption edge of Ag2Se-Graphene/TiO2 composites.
- Published
- 2012
- Full Text
- View/download PDF
42. Fabrication of large size graphene and Ti- MWCNTs/ large size graphene composites: their photocatalytic properties and potential application
- Author
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Won-Chun Oh and Kefayat Ullah
- Subjects
Multidisciplinary ,Materials science ,Graphene ,Graphene foam ,Chemical vapor deposition ,Carbon nanotube ,engineering.material ,Article ,law.invention ,Coating ,law ,Photocatalysis ,engineering ,Composite material ,Graphene nanoribbons ,Graphene oxide paper - Abstract
Large size graphene (LSG) and multiwall carbon nanotubes (MWCNTs) on LSG were synthesized on a copper surface via chemical vapor deposition (CVD) at low temperature and normal pressure. The LSG were formed through an easy chemical cyclic reaction in which liquid benzene was heated to a temperature below its boiling point to create benzene vapors as graphene precursor material. The reaction mechanism was observed and the time-dependent analysis of the reaction revealed that mounds of the carbon nanotubes had grown as a result of the island that was found on the LSG sheet. The implications of the mechanism that we have introduced were investigated by coating a titanium sheet on the MWCNTs/LSG and LSG on the semiconductor electronic device. The photonic response was observed to be markedly high, which can be attributed to the positive synergetic effect between the Ti and LSG sheet of our prepared composites.
- Published
- 2015
43. Cloning and expression of Neospora caninum dense-granule 7 in E. coli
- Author
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Marziye Kefayat, Masoud Reza Seifiabadshapoori, Hossein Hamidinejat, Saad Gooraninejad, Parviz Shayan, and Mohammad Mehdi Namavari
- Subjects
Cloning ,Expression vector ,biology ,lac operon ,biology.organism_classification ,Molecular biology ,Neospora caninum ,law.invention ,Plasmid ,law ,Immunology ,parasitic diseases ,Recombinant DNA ,Parasitology ,Original Article ,Vector (molecular biology) ,Dense granule - Abstract
Neospora caninum is an obligate intracellular protozoan which induces abortion, still birth and neuromuscular disorders in cattle and is an important problem in dairy and beef industry worldwide. The dense granule protein 7 (GRA7) of N. caninum is an immune-dominant protein shared by both tachyzoite and bradyzoites. This study was conducted to produce recombinant GRA7 of N. caninum using a plasmid with high level of expression of this protein in E. coli. For this purpose, a segment of N. caninum DNA corresponding to GRA7 was amplified using PCR. After sequencing, this fragment was cloned into expression vector pMAL-c2X under the control of the lac promoter. Expression of this plasmid in E. coli strain TG1 was identified by western blotting. In this study, pMAL-c2X had a strong promoter to produce high level expression of NcGRA7. This result revealed that this recombinant protein with pMAL-c2X vector may be suitable for developing of diagnostic procedures.
- Published
- 2012
44. Photoelectrocatalytic Electrodes with High Activity for Methylene Blue Degradation
- Author
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Kefayat Ullah, Meng ZeDa, Ye Shu, Zhu Lei, Oh WonChun, and Park ChongYeon
- Subjects
Graphene ,Photodissociation ,chemistry.chemical_element ,General Chemistry ,Photochemistry ,law.invention ,Catalysis ,chemistry.chemical_compound ,chemistry ,law ,Titanium dioxide ,medicine ,Degradation (geology) ,Cobalt ,Methylene blue ,Activated carbon ,medicine.drug - Published
- 2013
- Full Text
- View/download PDF
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