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Kanjwal, Muzafar A.,Barakat, Nasser A.M.,Sheikh, Faheem A.,Baek, Woo-Il,Khil, Myung-Seob,Kim, Hak-Yong 한국섬유공학회 2010 FIBERS AND POLYMERS Vol.11 No.5
As titanium oxide is a well-known photocatalyst, we investigated the effects of silver content and nanostructural morphology on the photocatalytic degradation of two dyes, methylene blue and rhodamine B. Two nano-formulations were utilized, including nanofibers and nanoparticles. Silver-grafted titanium oxide nanofibers were synthesized using the electrospinning of silver nitrate/titanium isopropoxide/poly(vinyl acetate) sol-gel. The nanoparticulate form was obtained by calcination of a ground powder prepared from the same electrospun sol-gel. The results affirmed the advantage of the silvergrafted titanium oxide nanostructures over the silver-free ones. Increasing the silver content in the nanofibers led to increases in their surface area, which is an important parameter in heterogeneous catalytic chemical reactions. Therefore, the results strongly suggest the use of silver-grafted titanium oxide in a nanofibrous form. These results further support utilizing Agloaded titanium oxide nanofibers as a photocatalyst.
Muzafar A. Kanjwal,Nasser A. M. Barakat,Faheem A. Sheikh,박수진,김학용 한국고분자학회 2010 Macromolecular Research Vol.18 No.3
In this study, a new hierarchical nanostructure consisting of zinc oxide (ZnO) and titanium dioxide (TiO2) was prepared by an electrospinning process followed by a hydrothermal technique for use as a photocatalyst for dye degradation. First, the electrospinning of a colloidal solution consisting of titanium isopropoxide/poly(vinyl acetate)/zinc nanoparticles was performed to produce polymeric nanofibers embedded in solid nanoparticles. Calcination of the obtained electrospun nanofiber mats in air at 600 ºC produced TiO2 nanofibers containing ZnO nanoparticles (i.e., ZnO-doped TiO2 nanofibers). The ZnO nanoparticles formed were then exploited as seeds to produce the outgrowth ZnO branches around the TiO2 nanofibers using the hydrothermal technique. Photodegradation of methyl red and rhodamine B (RB) dyes was examined individually using four photocatalysts:ZnO nanoparticles prepared by the same hydrothermal technique, pristine TiO2 nanofibers, ZnO-doped TiO2 nanofibers and the produced nanostructure. The results showed that the introduced ZnO-TiO2 hierarchical nanostructure can eliminate all the methyl red dye within 90 min and the rhodamine B dye within 105 min. However,the other three nanostructures could not totally remove any of the dyes, even after 3 h. Therefore, the introduced nanostructure has higher photocatalytic activity than any of its ingredients individually, which highlights the advantages of synthesizing this novel structure.
Gallium Arsenide (GaAs) Nanofibers by Electrospinning Technique as Future Energy Server Materials
Sheikh, Faheem A.,Barakat, Nasser A.M.,Kanjwal, Muzafar A.,Park, S.J.,Kim, Hern,Kim, Hak-Yong 한국섬유공학회 2010 FIBERS AND POLYMERS Vol.11 No.3
Gallium arsenide (GaAs) does have superior electronic properties compared with silicon. For instant, it has a higher saturated electron velocity and higher electron mobility. Weak mechanical properties and high production cost are the main drawbacks of this interesting semiconductor. In this study, we are introducing production of GaAs nanofibers by electrospinning methodology as a very low cost and yielding distinct product technique. In general, nano-fibrous shape is strongly improving the physical properties due to the high surface area to volume ratio of this nanostructure. The mechanical and environmental properties of the GaAs compound have been modified since GaAs nanofibers have been produced as a core inside a poly(vinyl alcohol) (PVA) shell. GaAs/PVA nanofibers were prepared by electrospinning of gallium nitrate/PVA solution in presence of arsenic vapor. The whole process was carried out in a closed hood equipped with nitrogen environment. FT-IR, XPS, TGA and UV-Vis spectroscopy analyses were utilized to confirm formation of GaAs compound. Transmission electron microscope (TEM) analysis has revealed that the synthesized GaAs compound is crystalline and does have nano-fibrous shape as a core inside PVA nanofibers. To precisely recommend the prepared GaAs nanofiber mats to be utilized in different applications, we have measured the electric conductivity and the band gap energies of the prepared nanofiber mats. Overall, the obtained results affirmed that the proposed strategy successfully remedied the drawbacks of the reported GaAs structures and did not affect the main physical properties of this important semiconductor.
Sheikh, Faheem A.,Barakat, Nasser A.M.,Kanjwal, Muzafar A.,Chaudhari, Atul A.,Jung, In-Hee,Lee, John-Hwa,Kim, Hak-Yong The Polymer Society of Korea 2009 Macromolecular Research Vol.17 No.9
In this study, a new class of polyurethane (PU) nanofibers containing silver (Ag) nanoparticles (NPs) was synthesized by electrospinning. A simple method that did not depending on additional foreign chemicals was used to self synthesize the silver NPs in/on PU nanofibers. The synthesis of silver NPs was carried out by exploiting the reduction ability of N,N-dimethylformamide (DMF), which is used mainly to decompose silver nitrate to silver NPs. Typically, a sol-gel consisting of $AgNO_3$/PU was electrospun and aged for one week. Silver NPs were created in/on PU nanofibers. SEM confirmed the well oriented nanofibers and good dispersion of pure silver NPs. TEM indicated that the Ag NPs were 5 to 20 nm in diameter. XRD demonstrated the good crystalline features of silver metal. The mechanical properties of the nanofiber mats showed improvement with increasing silver NPs content. The fixedness of the silver NPs obtained on PU nanofibers was examined by harsh successive washing of the as-prepared mats using a large amount of water. The results confirmed the good stability of the synthesized nanofiber mats. Two model organisms, E. coli and S. typhimurium, were used to check the antimicrobial influence of these nanofiber mats. Subsequently, antimicrobial tests indicated that the prepared nanofibers have a high bactericidal effect. Accordingly, these results highlight the potential use of these nanofiber mats as antimicrobial agents.
Barakat, Nasser A. M.,Farrag, Taha E.,Kanjwal, Muzafar A.,Park, Soo-Jin,Sheikh, Faheem A.,Yong Kim, Hak WILEY-VCH Verlag 2010 European journal of inorganic chemistry Vol.2010 No.10
<P>In this study, we have introduced electrospinning of a colloidal solution rather than the conventional sol–gel process as a novel strategy to produce silver nanofibres. Typically, a silver acetate/polyvinyl alcohol colloidal solution was successfully electrospun. Electrophoretic light scattering (ELS) and dynamic light scattering (DLS) analyses have affirmed that the electrospun solution is a colloid with a ζ-potential of –2 mV and average particle diameter of 373 ± 1 nm. Moreover, FTIR analysis affirmed that neither the polymer nor silver acetate nanoparticles were affected during the electrospinning process. Calcination of the electrospun mats at 700 °C in an argon atmosphere produced smooth and unbroken pure silver nanofibres. Surface plasmon resonance of the resultant silver nanofibres was detected at 962 nm which is biologically beneficial. Furthermore, the synthesised silver nanofibres revealed thermal hysteresis in the electrical conductivity properties. These advantageous physical features strongly suggest utilising the prepared nanofibres in various fields.</P> <B>Graphic Abstract</B> <P>Electrospinning of a colloidal silver acetate solution rather than the conventional sol–gel process was introduced as a novel strategy to produce silver nanofibres. Electrophoretic light scattering and dynamic light scattering analyses have affirmed that theelectrospun solution is a colloid. Calcination of the electrospun mats produced smooth and unbroken pure silver nanofibres. The advantageous physical features of the fibres suggest utilising the prepared nanofibres in various fields. <img src='wiley_img_2010/14341948-2010-2010-10-EJIC200900453-fig000.gif' alt='wiley_img_2010/14341948-2010-2010-10-EJIC200900453-fig000'> </P>
Muzafar A. Kanjwal,Martin Alm,Peter Thomsen,Nasser A. M. Barakat,Ioannis S. Chronakis 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.33 No.-
TiO2 and TiO2–Ag nanofibers were produced by electrospinning technique and surface coated on siliconeelastomer (diameter: 10.0 mm; thickness: 2.0 mm) by dipcoating method. These coated hybridnanoporous matrices were characterized by various morphological and physicochemical techniques(like SEM, TEM, XRD, FTIR, EDS and UV). These characterizations reveal that the surface morphology ofelectrospun nanofibers remain intact by the dipcoating technique. The produced hybrid matrices of TiO2and TiO2–Ag silicone were utilized as photocatalysts to degrade dairy waste water with an efficientwater flux and water photosplitting properties.
Kanjwal, Muzafar A.,Sheikh, Faheem A.,Nirmala, R.,Macossay, Javier,Kim, Hak-Yong 한국섬유공학회 2011 FIBERS AND POLYMERS Vol.12 No.1
In the present study, we introduce poly(caprolactone) (PCL) nanofibers that contain hydroxyapatite (HAp) nanoparticles (NPs) as a result of an electrospinning process. A simple method that does not depend on additional foreign chemicals has been employed to synthesize HAp NPs through calcination of bovine bones. Typically, a colloidal gel consisting of PCL/HAp has been electrospun to form nanofibers. Physiochemical aspects of prepared nanofibers were characterized for FE-SEM, TEM, XRD and FTIR which confirmed nanofibers were well-oriented and had good dispersion of HAp NPs. Parameters affecting the utilization of the prepared nanofibers in various nano-biotechnological fields have been studied; for instance, the bioactivity of the produced nanofiber mats was investigated while incubated with stimulated body fluid (SBF). The results from incubation of nanofibers in SBF indicate that incorporation of HAp strongly activates precipitation of the apatite-like materials because the HAp NPs act as seeds that accelerate crystallization of the biological HAp from the utilized SBF.
김학용,Muzafar A. Kanjwal,Faheem A. Sheikh,G. Gana kumar,Dae Kwang Park,Hak Yong Kim 한양대학교 세라믹연구소 2010 Journal of Ceramic Processing Research Vol.11 No.4
In this study, the performance of titanium oxide to be used as an anode in lithium ion batteries has been improved by producing this oxide in nanofibrous form and outgrowing zinc oxide nanobranches around the titanium oxide nanofibers obtained. First, electrospinning of a colloidal solution consisting of titanium isopropoxide/poly(vinyl acetate) zinc nanoparticles has been achieved to produce polymeric nanofibers embedding solid nanoparticles. Calcination of the electrospun nanofibers mats obtained in air at 600 oC produced TiO2 nanofibers containing ZnO nanoparticles; ZnO-doped TiO2 nanofibers. The ZnO nanoparticles formed have been exploited as seeds to outgrow ZnO branches around the TiO2 nanofibers using a hydrothermal technique. As an anode in a lithium ion battery, the prepared nanostructure exhibited a high rate capacity of 1232 mAhg−1. Considering the distinct physiochemical characteristics of TiO2, the proposed nanostructure might open an avenue for TiO2 to be used for high energy density lithium-ion batteries with higher performances.