Nanomaterials & Nanotechnology
Stella C; Ramachandran K
Abstract
Undoped and Co3O4-loaded (5, 10, and 15 at.%) SnO2 nanoparticles were prepared by a simple co-precipitation method. X-ray diffraction (XRD) study confirmed the presence of tetragonal phase of SnO2 and cubic stage of Co3O4 in accumulation to this the preferred orientation and texture coefficient were ...
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Undoped and Co3O4-loaded (5, 10, and 15 at.%) SnO2 nanoparticles were prepared by a simple co-precipitation method. X-ray diffraction (XRD) study confirmed the presence of tetragonal phase of SnO2 and cubic stage of Co3O4 in accumulation to this the preferred orientation and texture coefficient were derived. The texture coefficient of (200) plane increases with parallel decrease in (110) plane, which indicate the development of voids like vacancies along (110) direction. Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) analyses recognized the uniform dispersion of spherical shaped nanoparticles. EDS analysis confirmed the impurity absence in the prepared samples. UV-Vis absorption analysis confirmed that the optical band gap will get red shifted from bulk which is due to the agglomeration of nanoparticles and also due to the influences of Co3O4. The absorption peaks broadens after loading Co3O4 which indicate the surface related defects in the samples. The refractive indices derived from the band gap values had confirmed the fiber-optic sensor working under the leaky mode operation. Vibrating sample magnetometer (VSM) results confirmed the behavior of ferromagnet in pure SnO2 and antiferromagnet stage in Co3O4 loaded SnO2. The undoped SnO2 with room temperature ferromagnetism (RTFM) shows better sensitivity. The sensitivity of SnO2 and Co3O4 loaded SnO2 samples were 0.076 and 0.084, respectively. The enhanced sensitivity of Co3O4 loaded SnO2 was due to the high catalytic activity of Co3O4.
Carbon Materials and Technology
Sung Yong Kim; Megha Chitranshi; Anuptha Pujari; Vianessa Ng; Ashley Kubley; Ronald Hudepohl; Vesselin Shanov; Devanathan Anantharaman; Daniel Chen; Devika Chauhan; Mark Schulz
Abstract
This paper addresses the design of a reactor system for manufacturing carbon nanotube (CNT) fabric and carbon hybrid materials (CHM). A web or sock of CNT is formed in a reactor tube in the gas phase pyrolysis method. The sock exits the reactor tube and is wound layer by layer onto a drum to directly ...
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This paper addresses the design of a reactor system for manufacturing carbon nanotube (CNT) fabric and carbon hybrid materials (CHM). A web or sock of CNT is formed in a reactor tube in the gas phase pyrolysis method. The sock exits the reactor tube and is wound layer by layer onto a drum to directly form a nonwoven fabric. Metal nanoparticles and continuous microfibers can be integrated into the synthesis process to form CHM. Continuous direct manufacturing of fabric is an advantage of the method. However, the reliability of this manufacturing process in our particular reactor system is affected by several problems. These include occasional breaking of the sock, the need for daily cleaning of the ceramic reactor tube due to carbon deposits on the inside, sagging/bending of the reactor tube, and safety in handling the hydrogen gas produced from the reaction. Possible solutions to the problems are proposed. The importance of this research is that no other bulk material has the combination of properties of CNT hybrid fabric. If the properties can be further improved and customized, and if manufacturing of the material can be scaled-up at reasonable cost, many new commercial applications for nanotube custom materials could open up.
Carbon Materials and Technology
Sung Yong Kim; Megha Chitranshi; Anuptha Pujari; Vianessa Ng; Ashley Kubley; Ronald Hudepohl; Vesselin Shanov; Devanathan Anantharaman; Daniel Chen; Devika Chauhan; Mark Schulz
Abstract
The overall hypothesis for this paper is that accurately tuning the gas phase pyrolysis synthesis process and using appropriate raw materials will enable manufacturing different types of carbon hybrid materials (CHM). Optimizing multiple variables including particle melting and vaporization temperatures, ...
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The overall hypothesis for this paper is that accurately tuning the gas phase pyrolysis synthesis process and using appropriate raw materials will enable manufacturing different types of carbon hybrid materials (CHM). Optimizing multiple variables including particle melting and vaporization temperatures, fuel flow rate, gas flow rates, gas velocity, and sock wind-up speed is needed to achieve reliability of the synthesis process. Results from our specific reactor are presented to show how the process variables interact and how they affect CNT sock yield and stability. Metal nanoparticle (NP) injection enables the formation of hybrid materials. Several types of CHM materials created by incorporating different types of NPs into the carbon nanotube (CNT) synthesis process and CNT sock are discussed. Many possible combinations of metal NPs can be used in the process to customize the properties of CHM. However, it is a complex problem to determine what metal compounds can chemically join with CNT. Some of the first results testing the new CHM process are presented in this paper.
Raghavendra K. Sali; Malatesh S. Pujar; Shivaprasadagouda Patil; Ashok H. Sidarai
Abstract
In this work, using Macrotyloma Uniflorum leaves an affordable and eco-friendly, ZnO and Ag-ZnO metal oxide nanoparticles were reported. Ensuing ZnO and Ag-ZnO nanoparticles were characterized by UV–visible spectroscopy, FT-IR Spectroscopy, X-ray diffraction, Scanning Electron Microscopy with Energy ...
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In this work, using Macrotyloma Uniflorum leaves an affordable and eco-friendly, ZnO and Ag-ZnO metal oxide nanoparticles were reported. Ensuing ZnO and Ag-ZnO nanoparticles were characterized by UV–visible spectroscopy, FT-IR Spectroscopy, X-ray diffraction, Scanning Electron Microscopy with Energy Dispersive Spectroscopy, Transmission Electron Microscopy, and Dynamic Light Scattering. The green synthesized ZnO and Ag-ZnO nanoparticles comprise an average size of about 120.16 nm and 91.17 nm respectively. The minimum inhibitory concentrations (MIC) of these ZnO and Ag-ZnO nanoparticles and mixtures thereof, Ag-ZnO, were determined on B.subtilis, Streptococci and E.coli cultures. MIC and their antimicrobial activity were studied in vitro; both types of nanoparticles showed high antibacterial activity. Also, it has shown excellent results with MIC value of 62.5 µg/ml for antibacterial activity against ZnO and Ag-ZnO nanoparticles. The Ag-ZnO nanoparticles were shown better antimicrobial effect than the ZnO nanoparticles. So, we can strongly suggest these green synthesized nanoparticles as a potent agent for biological applications.
Jagriti Behl; Raksha Saini
Abstract
Mn and Cu-doped Cr2O3 nanoparticles were prepared by the co-precipitation method followed by calcination at 400 0 C for 3h. These synthesized nanoparticles were characterized by Fourier Transform Infrared spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning electron microscope (SEM), Energy-dispersive ...
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Mn and Cu-doped Cr2O3 nanoparticles were prepared by the co-precipitation method followed by calcination at 400 0 C for 3h. These synthesized nanoparticles were characterized by Fourier Transform Infrared spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning electron microscope (SEM), Energy-dispersive X-ray spectroscopy, and UV/Visible spectroscopy. SEM images showed the irregular and nearly spherical structure of the Undoped and doped Cr2O3 nanoparticles respectively. The particle size of obtained nanoparticles exhibits in the range of 30-60 nm. X-ray diffraction study reveals at temperature 400 0 C, undoped and Cu-doped Cr2O3 nanoparticles exist in the crystalline phase and Mn-doped Cr2O3 nanoparticles exist in the amorphous phase. UV-Visible spectra have been used to determine the band gap of the synthesized nanoparticles. The optical band gap value has been calculated by using Tauc’s method and Kubelka Munk method. Results indicate band gap calculated by Kubelka-Munk method is higher (4.7, 4.5 and 4.32 eV) than Tauc’s method. (4.18, 4.0, 3.96 eV). It is also concluded the decrease in the band gap (in both Tauc’s and Kubelka Munk method) was observed by the addition of dopant.
Pooja Y. Raval; Shrey K. Modi; Khayati G. Vyas; Priya L. Mange; Kunal B. Modi
Abstract
Temperature-dependent electrical transport characteristics of un-milled and high-energy ball-milled samples (3 h (70 nm), 6 h (55 nm) and 9 h (45 mm)) of Ni0.5Zn0.5Fe2O4 spinel ferrite were explored. A well-defined metal to semiconductor transition exhibited by all the samples has been construed ...
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Temperature-dependent electrical transport characteristics of un-milled and high-energy ball-milled samples (3 h (70 nm), 6 h (55 nm) and 9 h (45 mm)) of Ni0.5Zn0.5Fe2O4 spinel ferrite were explored. A well-defined metal to semiconductor transition exhibited by all the samples has been construed in view of direct and superexchange cationic interactions and delocalization to localization of charge carriers on increasing temperature. The peak temperature (Tmax) was found to shift towards a higher temperature side on milling principally governs by the lattice vibration scattering and intrinsic excitation. The crystallite size reduction, enhancement in strain and sudden decrease in the formation and octahedral site occupancy of Fe 2+ ions on milling found responsible for the prodigious rise (~ 250 times) in normalized resistivity values for the sample comminuted for 9 h. The spectrum of energies corresponds to charge trapping centers that cause small bump (3 h milled sample) and sharp cusp (9 h milled sample) for T>Tmax. These materials may be found suitable for thermal cutoff switching applications.
D. Chávez-García; K. Juarez-Moreno; R. Reyes; J. Barrera; G. A. Hirata
Abstract
This study is a summary of our results on synthesis, functionalization and biomedical application of luminescent lanthanide doped nanoparticles with Y2O3 as host lattice. The nanoparticles (NPs) studied were Y2O3 and Y2O3: Eu 3+ and they are water-monodispersed, synthesized by the sol-gel method and ...
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This study is a summary of our results on synthesis, functionalization and biomedical application of luminescent lanthanide doped nanoparticles with Y2O3 as host lattice. The nanoparticles (NPs) studied were Y2O3 and Y2O3: Eu 3+ and they are water-monodispersed, synthesized by the sol-gel method and surface modified to be biocompatible with a silica shell. The NPs were conjugated with amine groups and folic acid to detect specific cancer cells. We carried out a complete nanotoxicological evaluation of NPs in HeLa and MCF-7 cancer cells and fibroblast (L929) cell line. Our results corroborate the bio- and hemo-compatibility of NPs. No in vitro inflammatory response mediated by macrophages was elicited and no genotoxic effect was scored by comet assay. Internalization of folic acid-functionalized NPs was detected by flow cytometry comparing the internal cellular complexity and the cytoplasmic localization of NPs was confirmed by confocal microscopy. We provide with more evidences to warranty the biosafety of down conversion nanoparticles based on Y2O3: Eu 3+ and functionalized with folic acid for further biomedical and bio-imaging applications.
See Leng Tay; Chris Goode; Wei Gao
Abstract
The use of ceramic nano-powders to create composite coatings is well known but is neither simple to industrialize nor environmentally friendly. Patented Cirrus Dopant™ technology from Cirrus Materials Science offers the performance advantages of nano-composite coatings without the implementation ...
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The use of ceramic nano-powders to create composite coatings is well known but is neither simple to industrialize nor environmentally friendly. Patented Cirrus Dopant™ technology from Cirrus Materials Science offers the performance advantages of nano-composite coatings without the implementation and process drawbacks. Cirrus Dopant™ technology is applicable to commercial baths for a large variety of electrolytic and electroless deposited coatings including Ni, Ni-P, Ni-B, Co-P, Au, Ag, Sn, and Zn-Ni. Successful application of the technology simply requires optimization of a specialized Dopant™ to the bath. This paper discusses the process and results for nano-doping commercially important coating baths.
Hashem Al-Mattarneh; Mohamed Dahim
Abstract
The rapid development of electronic systems and telecommunications has resulted in a growing and intense interest in microwave electromagnetic absorber technology and microwave absorber materials. In this study, thermoplastic natural rubber barium ferrite composite was developed using micro and Nano ...
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The rapid development of electronic systems and telecommunications has resulted in a growing and intense interest in microwave electromagnetic absorber technology and microwave absorber materials. In this study, thermoplastic natural rubber barium ferrite composite was developed using micro and Nano barium ferrite filler. This paper presented the improvement of the mechanical properties of the thermoplastic natural rubber barium ferrite (TPNR-BF) composite when the size of barium ferrite filler changed from 3 um to 55 nm. TPNR was prepared as hosting material, and the barium ferrite with particle size 3 um was used as filler. Five samples of the composite were prepared with barium ferrite content range from 0% to 20% by an increment of 5%. The same procedure was used to prepare five samples using barium ferrite with a particle size of 55 nm. Physical and Mechanical properties of the composite were determined such as density, SEM, hardness, stiffness, tensile stress, and strain. Also, the magnetic properties and hysteresis diagram and SEM were evaluated for both composites barium ferrite types. The results indicate that all mechanical properties decline with the increasing BF content due to the increasing size of the weak interfacial zone between the polymer and the filler. This trend could be enhanced by replacing the micro barium ferrite with Nanosize barium ferrite. The level of improvement in mechanical properties increases at high filler content.
Jin-Woo Park; Kwang-Ho Kim; Nong-Moon Hwang
Abstract
The effect of the substrate bias on the diamond deposition was studied using a hot filament chemical vapor deposition (HFCVD) reactor. Both growth rate of diamonds and sp < sup > 3 /sp < sup > 2 ratio increased with increasing the substrate bias from – 200 V to + 45 V. At + 60 V where ...
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The effect of the substrate bias on the diamond deposition was studied using a hot filament chemical vapor deposition (HFCVD) reactor. Both growth rate of diamonds and sp < sup > 3 /sp < sup > 2 ratio increased with increasing the substrate bias from – 200 V to + 45 V. At + 60 V where the DC glow discharge occurred, however, the data deviated significantly from the tendency. These results were explained by the new concept of non-classical crystallization, where a building block of diamond growth is a charged nanoparticle rather than an atom. Based on the previously reported experimental confirmation of the gas phase generation of negatively-charged diamond nanoparticles, the bias effect on the diamond deposition behavior could be consistently explained.
Stefan Andersson; Paul Inge Dahl; Stephen A. Shevlin; Ingeborg-Helene Svenum; Yngve Larring; Julian R. Tolchard; Zheng Xiao Guo
Abstract
Experimental and complementary modelling studies on the potential use of iron oxide nanoparticles in chemical looping reforming processes have been performed. In order to avoid coarsening of the nanoparticles, and thereby loss of reactivity, at relevant process temperatures (700-900°C), the active ...
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Experimental and complementary modelling studies on the potential use of iron oxide nanoparticles in chemical looping reforming processes have been performed. In order to avoid coarsening of the nanoparticles, and thereby loss of reactivity, at relevant process temperatures (700-900°C), the active metal oxide was embedded in an inert support material of lanthanum silicate. Micro reactor tests indicate that partial combustion occurs in reactions of reduced iron oxide with methane instead of pure reforming. Density Functional Theory and kinetic Monte Carlo calculations have been used to support and complement the experiments. The modelling supports efficient reactivity towards exposure of hydrogen, which is also observed experimentally. Reactivity towards methane is only tested for the fully oxidized state, Fe2O3, and not for the reduced oxide, giving results that are complementary to the experiments. Copyright © 2018 VBRI Press.
Rickard Andersson; Amin M. Saleem; Ioanna Savva; Theodora Krasia-Christoforou; Peter Enoksson; Vincent Desmaris
Abstract
Carbon nanostructures are of great interest for a variety of applications, but their current processing throughput limits their industrial full scale deployment. This paper presents a cost effective and simple fabrication process, where vertically aligned carbon nanofibers are grown using DC-PECVD at ...
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Carbon nanostructures are of great interest for a variety of applications, but their current processing throughput limits their industrial full scale deployment. This paper presents a cost effective and simple fabrication process, where vertically aligned carbon nanofibers are grown using DC-PECVD at CMOS compatible temperatures from catalytic nanoparticles, spin-coated from stable polymer-nanoparticle colloidal suspensions. Two different catalysts, Co and Cu, are investigated by growing carbon nanofibers at temperatures ranging from 390°C to 550°C, using suspensions with various concentrations of nanoparticles. The length and morphology of the grown nanofibers are examined using SEM and the electrical properties are investigated using electrochemical measurements on samples arranged as supercapacitor devices. Vertically aligned CNFs are successfully grown from both types of catalyst. The Co-derived fibers are long and arranged in a denser carpet-like structure, while the Cu-derived fibers are shorter and in a sparser formation of free-standing individual fibers. All electrochemical measurements show typical supercapacitor behaviour even at high scan rates of 200 mVs -1 , with the fibers grown from Co showing great increase in capacitance over the bare chip reference device, including the samples grown at 390°C.
Yanyu Zhang; Palas Baran Pati; Haining Tian
Abstract
Organic semiconducting polymer nano-particles, as nano-photocatalysts for light driven proton reduction, have been prepared by using Triton X-100 as surfactant. The nano-photocatalysts prepared by Triton X-100 showed well dispersibility in water and no precipitation observed after photocatalysis. The ...
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Organic semiconducting polymer nano-particles, as nano-photocatalysts for light driven proton reduction, have been prepared by using Triton X-100 as surfactant. The nano-photocatalysts prepared by Triton X-100 showed well dispersibility in water and no precipitation observed after photocatalysis. The effect of molecular weight and concentration on photocatalysis has been investigated, indicating that the particle size shows significant influence on photocatalytic performance. The sample with 100 µg/ml photocatalysts gave the best hydrogen evolution amount of 0.4 µmol/ml and apparent quantum yield of 1.3% at 450 nm.
Glécia V. S. Luz; Wang. S. Hui; Renata C. Roncoleta; Pedro H. O. Nogueira; Lourdes M. Brasil; Pilar Hidalgo
Abstract
This research aimed to build hybrid solar cells, based on Grätzel method. We used the Polyethylene Terephthalate (PET) polymer as a substrate containing a layer of Indium Tin Oxide (ITO). Films of ZnO nanoparticles (ZnO NPs) synthesized by Pechini Method, and four different dyes were tested: Congo ...
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This research aimed to build hybrid solar cells, based on Grätzel method. We used the Polyethylene Terephthalate (PET) polymer as a substrate containing a layer of Indium Tin Oxide (ITO). Films of ZnO nanoparticles (ZnO NPs) synthesized by Pechini Method, and four different dyes were tested: Congo Red (CR), Bromocresol Green (BG), Acridine Orange (AO) and a Ruthenium Complex (RC). ZnO NPs were analyzed by XRD, which generated peaks corresponding to hexagonal wurtzite crystalline structure. We also conducted analysis by UV–Vis. Spectroscopy and Transmission Electron Microscope (TEM). Rietveld analysis determined the crystal size of 115.23 ± 28.16 nm. The deposition of ZnO and dye thin films were made through spin-coating. The electrical properties of the formed films were characterized with Van der Pawn method. Efficiency in converting light in electricity under an OSRAM 20W light bulb was tested after the devices were built. The smaller sheet resistance results were obtained for material containing: PET/ITO/ZnO/CR and PET/ITO/ZnO/AO. As expected, the best open-circuit voltage (Voc) results reached were 64 and 73 mV to CR and AO, respectively. Therefore, the results demonstrated satisfactory interaction between the ZnO-Dye-Electrolyte layers.
Amel Tounsi; Djahida Talantikite-Touati; Hamid Merzouk; Hadjira Haddad; Roumaïssa Khalfi
Abstract
The thin layers of undoped ZnS and ZnS doped La with different concentrations (2, 4, 6, 8 and 10%) were deposited on glass substrates using sol-gel and dip-coating methods. The structural characterization of these samples was carried out by the X-rays diffraction (XRD), scanning electron microscopy ...
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The thin layers of undoped ZnS and ZnS doped La with different concentrations (2, 4, 6, 8 and 10%) were deposited on glass substrates using sol-gel and dip-coating methods. The structural characterization of these samples was carried out by the X-rays diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). UV-visible and Fourier Transform Infrared spectroscopy (FTIR) have been used to study the effect of dopant on the optical properties of ZnS doped La thin films. Atomic force microscopy images of the films have revealed homogeneous and granular structure and the SEM micrographies show deposit films with uniform and porous structure. The optical transmission spectra in the UV - visible range have shown that all the doped films present a good optical transmission in the visible domain.
Abstract
Zinc oxide (ZnO) nanoparticles (NPs) were synthesized by different methods known as Pechini and Sol-Gel. It was observed during the experiments significant differences comparing these methods as: particle size, time applied, crystallinity and chemical residues generated by-products. The NPs were analysed ...
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Zinc oxide (ZnO) nanoparticles (NPs) were synthesized by different methods known as Pechini and Sol-Gel. It was observed during the experiments significant differences comparing these methods as: particle size, time applied, crystallinity and chemical residues generated by-products. The NPs were analysed by X-ray diffraction (XRD), ultraviolet-visible (UV-Vis.) absorption and Raman spectroscopy techniques. X-Ray Difractograms showed peaks corresponding to hexagonal wurtzite crystalline structure. It was observed that NPs obtained by the Pechini showed better homogeneity and crystallinity; these presented average size of 115 nm. The NPs produced by Sol-Gel method showed crystallites with smaller average size of 8 nm. The band gap energy (Eg) obtained using UV-Vis for ZnO NPs synthesized by Pechini was 3.39 eV. Still, the results for Sol-Gel method with 5 and 10 hours of reactions were 3.53 eV and 3.55 eV respectively. Raman data obtained by Pechini and Sol-Gel Methods showed characteristics peaks. The obtained data confirmed the ZnO phase samples and the proportional relationship to the enlargement with the intensity of peaks E2 High ˜ 438 cm -1 , as evidenced by literature. These results lead to the applicability of both NPs in optoelectronic and fluorescent applications.
Christina Kr
Abstract
Recently, a new approach was developed and published which focuses on the preparation of inorganic foams and their application in foam concrete production. Through the incorporation of nanostructured pozzolans in the foam structure, so-called three-phase-foams show a higher stability than foams only ...
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Recently, a new approach was developed and published which focuses on the preparation of inorganic foams and their application in foam concrete production. Through the incorporation of nanostructured pozzolans in the foam structure, so-called three-phase-foams show a higher stability than foams only based on surfactants. Due to pozzolanic hardening, shrinkage cracks were healed and reaction products can be observed. By implementation of nanotubes in the foam structure as nanoreinforcement, a further stabilization was reached. After incorporation of wet three-phase-foams in cement paste, foam concretes with improved mechanical properties were achieved. It was also shown that the pore size distribution was similar to the introduced three-phase-foams and also smaller pore sizes can be observed compared to foam concretes based on surfactant foams. Additionally, a specific shell-like pore structure was obtained and a theoretical model developed. This could be confirmed by investigations of the influence of the surfactant used on the formation and carbonation of calcium hydroxide. To further enhance the mechanical properties of foam concretes based on three-phase-foams, an UHPC (Ultra-high Performance Concrete) formulation has been applied. Resultant UHPC foam concretes showed dense packed borders, improved homogeneity related to the pore size distribution and enhanced mechanical properties. Furthermore, the UHPC approach was combined with nanoreinforcement.
Nitin R. Dighore; Suresh T. Gaikwad; Anjali S. Rajbhoj
Abstract
The fabrication of an electrochemical sensor based on polypyrrole-Pd nanocomposites modified gold electrode (PPy-Pd-AuE) and its electrodetection of ascorbic acid is described. The PPy-Pd nanocomposites were synthesized by chemical method and characterized by different techniques. The Pd nanoparticles ...
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The fabrication of an electrochemical sensor based on polypyrrole-Pd nanocomposites modified gold electrode (PPy-Pd-AuE) and its electrodetection of ascorbic acid is described. The PPy-Pd nanocomposites were synthesized by chemical method and characterized by different techniques. The Pd nanoparticles incorporated with PPy were confirmed by x-ray diffraction, scanning electron microscope, elemental dispersive spectroscopy and transmission electron microscopy analysis. The electrochemical behavior of polypyrrole-Pd nanocomposites towards the electro catalytic oxidation of ascorbic acid was investigated by cyclic voltammetry, differential pulse voltammetry and square wave voltammetry. The observed cyclic voltammetry, differential pulse voltammetry and square wave voltammetry response depended linearly on concentration of ascorbic acid in the range of 100-1000 mM with correlation coefficients of R 2 =0.977, R 2 =0.980, R 2 = 0.990 and sensitivity 7.96 mA/mM.cm 2 , 0.70 mA/mM.cm 2 and 2.10 mA/mM.cm 2 respectively. The reproducibility of PPy-Pd-AuE electrode from CV, DPV and SWV were found to be 3.9%, 4.69% and 2.98 % respectively. These results indicate the PPy-Pd-AuE exhibited excellent platform and could be used for electrochemical determination of ascorbic acid.
Vishal S. Makadia; Lalit M. Manocha; Satish Manocha; Hasmukh L. Gajera
Abstract
A freeze-thaw technique is put forth as a novel approach to exfoliating graphene oxide sheets (GO-sheets) in aqueous media. This method does not use shear force or high-temperature treatment at any stage. Avoiding these factors prevents scrolling and promotes defect-free synthesis of the graphitic ...
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A freeze-thaw technique is put forth as a novel approach to exfoliating graphene oxide sheets (GO-sheets) in aqueous media. This method does not use shear force or high-temperature treatment at any stage. Avoiding these factors prevents scrolling and promotes defect-free synthesis of the graphitic planes. The research shows how the freeze-thaw technique successfully exfoliates graphitic planes without producing scrolls or defective graphene oxide planes. Further, when compared to conventional exfoliation methods, it was found that the freeze-thaw technique increased the surface area significantly.
Atikah Ali; Rubia Idris
Abstract
In this study, the low-cost activated carbon from pistachio shell waste was sought through experiments using rapid synthesis of microwave-induced pyrolysis. The effect parameters of activating agents and microwave power on the surface area and carbon yield were studied. The results revealed that, well-grown ...
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In this study, the low-cost activated carbon from pistachio shell waste was sought through experiments using rapid synthesis of microwave-induced pyrolysis. The effect parameters of activating agents and microwave power on the surface area and carbon yield were studied. The results revealed that, well-grown pore structures with the highest surface area (681.2 m 2 g -1 ) and the highest carbon yield (70.3%) were produced using K2CO3 as an activating agent and 600 W power level exposed to 15-minute irradiation. The activated carbon with the highest porosity (AC600) was subsequently utilized in the tungsten carbide (WC) preparation which employed a facile method of mechanical milling. Finally, a high-thermal treatment under inert conditions was performed to completely convert W into WC. The physicochemical properties of the catalyst were evaluated by N2 adsorption-desorption, XRD, FESEM and TEM. It was observed that, the tungsten carbide produced was small and uniform spherical nanoparticles with average diameters of 60 to 100 nm. High porosity and high surface area of catalyst support were identified as factors leading to a homogeneous distribution of metal catalyst. Therefore, the nanoparticles of WC produced were attributed to activated carbon with high porosity (AC600) due to well distribution of the tungsten crystal phase.
Seelam Harinath Babu; Shaik Kaleemulla
Abstract
To fabricate spintronics devices with easy of processing we require reliable dilute magnetic semiconductors (DMS) at room temperature. Here we report the development of DMS material based on Indium tin oxide (ITO) with optimal tin concentration ((In0.95Sn0.05)2O3). The ITO and Ni-doped ITO nanoparticles ...
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To fabricate spintronics devices with easy of processing we require reliable dilute magnetic semiconductors (DMS) at room temperature. Here we report the development of DMS material based on Indium tin oxide (ITO) with optimal tin concentration ((In0.95Sn0.05)2O3). The ITO and Ni-doped ITO nanoparticles were synthesized in quartz tube under reduced pressure at elevated temperature. The stoichiometric samples were crystallined in cubic bixbyite structure with change in the unit cell volume with Ni doping and shown average particle size of 50 nm in electron micrographs. Estimated energy band gap of Ni-doped ITO is found to be 3.15 eV. The magnetic properties of materials revealed that optimal doping of Sn gives highest magnetization and further increase of doping with Ni 2+ ions in In 3+ sites lead to deterioration of ferromagnetism induced by Sn 4+ . The observed ferromagnetism is attributed to the localized ferromagnetic exchange interactions induced by spin polarized electrons trapped in oxygen vacancies. The deterioration of ferromagnetism is attributed to excess anionic vacancies created by Ni doing and promotion of antiferromagnetic exchange with increase of Ni 2+ ion concentration as evidenced from magnetic hysteresis loop at 100 K.
Aditya Sharma; Shalendra Kumar;Hyun-Joon Shin; Mayora Varshney; Sejun Kang; Jaeyoon Baik; Tae-Kyun Ha; Keun-Hwa Chae
Abstract
ZrO2 and HfO2 powder samples were prepared by using the chemical precipitation method and subsequent annealing. Crystal structure, local electronic structure and dielectric constant of amorphous and crystalline powders of ZrO2 and HfO2 have been examined using the synchrotron X-ray diffraction, O K-edge ...
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ZrO2 and HfO2 powder samples were prepared by using the chemical precipitation method and subsequent annealing. Crystal structure, local electronic structure and dielectric constant of amorphous and crystalline powders of ZrO2 and HfO2 have been examined using the synchrotron X-ray diffraction, O K-edge X-ray absorption spectroscopy, Zr 3d and Hf 4f core-level X-ray photoelectron spectroscopy and temperature dependent dielectric measurements, respectively. Amorphous ZrO2 and HfO2 powders exhibit a local tetragonal structure, with mixed +3 and +4 valence states of Zr and Hf ions, and demonstrated the high dielectric performance. After the heat treatment, the tetragonal phase transforms into the monoclinic phase with dominant +4 valence state of Zr and Hf ions and the larger sized ZrO2 and HfO2 nanoparticles exhibited low dielectric constant. The manifestation of high dielectric constants in the amorphous ZrO2 and HfO2 samples is because of the hopping of electrons between the Zr +3 -Zr +4 and Hf +3 -Hf +4 networks.
Mahuya Bandyopadhyay; Hermann Gies; Wolfgang Gr
Abstract
The interpenetrating 3-dimensional channel system of silica MCM-48 has been selected for the deposition of ZnO nanoparticles. The post-synthetic organometallic route was employed to load the mesoporous silica with ZnO-precursor molecule. Calcination of the composite transformed the organometallic sorbate ...
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The interpenetrating 3-dimensional channel system of silica MCM-48 has been selected for the deposition of ZnO nanoparticles. The post-synthetic organometallic route was employed to load the mesoporous silica with ZnO-precursor molecule. Calcination of the composite transformed the organometallic sorbate to the corresponding metal oxide. X-ray powder diffraction, N2-Adsorption and TEM measurement have supported the efficient loading and growth of ZnO particles in the channels of mesoporous silica matrix. EXAFS analysis (ZnK-edges) also complemented the metal uptake. Presence of nano-dispersed and nanosized ZnO particles confined by the mesoporous pore system was established by TEM and EXAFS analysis.
Manpreet Kaur; K. L. Yadav; Poonam Uniyal
Abstract
Single phase Bi1-xLaxFeO3 nanoparticles have been successfully synthesized with varied concentration (0.0 ≤ x ≤ 0.2) for the photocatalytic degradation of an industrial dye. The room temperature X-ray diffraction (XRD) pattern of La 3+ doped BiFeO3 nanoparticles reveals the structural phase transition ...
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Single phase Bi1-xLaxFeO3 nanoparticles have been successfully synthesized with varied concentration (0.0 ≤ x ≤ 0.2) for the photocatalytic degradation of an industrial dye. The room temperature X-ray diffraction (XRD) pattern of La 3+ doped BiFeO3 nanoparticles reveals the structural phase transition from rhombohedral (R3c) to orthorhombic (Pnma) at x=0.1, which is further analyzed via Rietveld refinement. The La 3+ doped BiFeO3 nanoparticles have much negative enthalpy of formation (ΔHf) than undoped BiFeO3. The particle size gradually decreases from ~132 to ~68 nm with La 3+ doping. Magnetic and ferroelectric transition temperatures are found to be slightly shifted towards room temperature upto x= 0.1 and then higher temperature side which could be attribute to the particle size effect. All compositions presented weak ferromagnetic ordering, which indicates that the La 3+ substitution in the BiFeO3 matrix released the latent magnetization. The increase in the energy band gap from 2.045 to 2.658 eV with cutoff wavelengths 639.58 and 513.061 nm for x=0.0 and 0.2 respectively, increases the visible light efficiency of photocatalytic activity in La 3+ doped BiFeO3 samples. The photodegradation efficiency of La 3+ doped BiFeO3 for azo-dye RB-5 is observed to be ~27% higher as compared to the undoped BiFeO3 (43% photodegradation efficiency), which makes it suitable for visible-light responsive photocatalysis for photocatalytic applications.
Ashish Gupta; Deoram V. Nandanwar; Sanjay R. Dhakate
Abstract
Zinc oxide (ZnO) nanoparticles, self-assembled in the form of one dimensional ZnO nanofibers were synthesized using electrospinning technique from solution of polyvinyl alcohol (PVA) and zinc acetate followed by calcination at 600°C in oxidizing environment. Scanning Electron Microscope (SEM) analysis ...
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Zinc oxide (ZnO) nanoparticles, self-assembled in the form of one dimensional ZnO nanofibers were synthesized using electrospinning technique from solution of polyvinyl alcohol (PVA) and zinc acetate followed by calcination at 600°C in oxidizing environment. Scanning Electron Microscope (SEM) analysis demonstrates that morphology of ZnO nanofibers having rough surface and corresponding Energy Dispersive Spectrometry (EDAX) confirmed the Zn: O atomic ratio approximately in 50:50. Transmission electron microscopy (TEM) images clearly demonstrate the rough morphology is due to the self-assembling of ZnO nanoparticles having diameter approximately 50nm. X-ray Diffraction (XRD) reveals the polycrystalline structure and Raman spectra show some shifts in phonon modes. The PL graph show exceptional emission at 342nm due to band-band transition. Under solar radiations as produced ZnO nanofibers degrades the 99% of 25ppm acid fuchsine which proven through UV spectra when compared to blank dye solution. This shows that natural solar radiations are sufficient to excite theses self-assembled high surface area ZnO nanofibers to show its photocatalytic activity.
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