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MWCNT/PANI modified epoxy matrix was used to prepare glass fiber reinforced polymer laminates by wet-layup vacuum bagging method. The amount of the MWCNT/PANI in the epoxy matrix was varied from 0.5 to 3 wt% with respect to the epoxy-hardener system, where as the fiber amount kept constant. The electrical and mechanical properties of the laminates got enhanced after the addition of MWCNT/PANI in the epoxy matrix. The reflection loss has increased from −16 dB for the laminate with 0.5 wt% MWCNT/PANI to −30.1 dB for the one with 2 wt% MWCNT/PANI and thus the laminates can be used as radar absorbing material.

Glycine-assisted polyaniline-NiCo2O4 composite porous powder was synthesized by a simple chemical method. The FT-IR and UV-visible spectroscopy analysis confirmed the presence of the corresponding functional groups. Scanning electron microscopy revealed the porous morphology of NiCo2O4 and a brush-like morphology of PANi-NiCo2O4 composite which helps in enhancing the electrochemical performance of the composite. The X-ray diffraction pattern indicates the spinel crystal phase of NiCo2O4 in the synthesized sample. Cyclic voltammetry and impedance analysis were done to understand the electrochemical performance of the material. The specific capacitance calculated by galvanostatic charge-discharge method was found to be 687.5 F/g for PANi-NiCo2O4, whereas for NiCo2O4 and pure PANi, it was 458.5 F/g and 373.75 F/g respectively. Cyclic stability analysis showed 88% retention of specific capacitance over 1000 cycles for the as-synthesized PANi-NiCo2O4 sample.

A polyaniline (PANi)-carbon quantum dots (CQDs) nanocomposite material with CQDs made from a PEG (polyethylene glycol and NaOH) source was synthesized. This unique synthesis technique was developed to overcome the setbacks of the PEG method by using UG (urea and glycine). PANi was synthesized by chemical oxidation in the presence of CQDs, which were prepared according to the two above-mentioned methods. The sample was further characterized by morphological, optical, and electrochemical experiments. FE-SEM showed ridge-like morphology and UV-Vis studies revealed the presence of PANi and CQDs. HRTEM images gave details on the uniformly distributed polyaniline, which showed lengthy rod-like rough surfaces with interconnected tiny CQDs. The electrochemical results from CV and GCD studies indicated an enhancement of the specific capacitance for sample PCQ-2 (CQDs synthesized via the UG method as a source) compared to only PANi and PCQ-1 (CQDs prepared by the PEG method). The cyclic stability established was 84.5% retention from initial capacitance values over 3000 cycles. A two-electrode prototype device was also developed with the PCQ-2 sample and it achieved a reasonable capacitance of 161.3 mF/cm2 and demonstrated good retention stability over 5000 cycles. These results may be due to a variety of factors related to compositing CQDs (with urea and glycine as a source) with PANi.

Agriculture plays an important role in the livelihood and food security issues of impoverished communities that suffer from minimal development. This study is focused on understanding the challenges faced by an impoverished Musahar community in Ratanpur, Bihar, India. A naturalistic study was conducted which involved data collection methods through semi-structured interviews with villagers, field and observational analyses, meetings with key community leaders, and secondary data. Results revealed outdated irrigation techniques practiced by the small-scale farmers. Additionally, there is a lack of knowledge of how to create sustainable income for those dependent upon limited daily labour jobs for only few months of the year. But the overarching theme of the results indicated primary issues of lack of available resources that impact livelihood opportunities, which in turn affects economic and food security. These interconnected issues related to resource poverty can be addressed through the use of technological innovations that can compensate for lack of resources to support sustainable income generation activities and food security. Working in collaboration with villagers, we found out that novel kitchen gardens utilizing vertical farming methods can help to support economic and nutrition needs year-round. Also, innovative irrigation techniques could greatly help the village. Such interventions can contribute to poverty-alleviation and the sustainability of the village.

Bilayer and few layer-graphene (Gr) with noble metal (Ag and Au) and TiO2 nanoparticles were synthesized using atmospheric pressure radio frequency chemical vapor deposition (APRF-CVD). The precursors for the formation of the respective nanoparticles were dissolved in ethanol and injected into the APRF-CVD containing a Cu foil catalyst at 1000 °C. The graphene obtained had a blistered morphology similar to bubble-wrap. The bubble-like protrusions on the graphene sheet were caused by large nanoparticle clusters (~220 nm) formed below the graphene sheets. Smaller nanoparticles (10-80 nm) were also observed on top of the graphene sheets. Encapsulation of the nanoparticles with graphene, to yield core-shell particles was observed. Similarly, secondary growth of carbon nanotubes (CNTs) from the Au nanoparticles was observed. The average full width half maxima (FWHM) of 2D bands in the Raman spectra indicate that the graphene formed was predominantly bilayer graphene for Gr-TiO2 (55 ± 1.72 cm-1), and few-layer graphene for Gr-Ag (76 ± 22 cm-1) and Gr-Au (88 ± 4.7 cm-1). Raman spectroscopy also showed evidence for the doping of graphene and surface-enhanced Raman sensitivity (SERS) in the materials. These electronic properties of graphene with nanoparticles are relevant to various applications such as optoelectronics, catalysis, chemical and biological sensing.

Development of low cost, metal-free electrodes for photovoltaic applications is critical to meet future energy demands. In this work, the one-step hydrothermal synthesis and electrocatalytic activity of molybdenum disulfide/reduced graphene oxide (MoS2-rGO) hybrids are investigated as high-performance counter electrode materials for dye-sensitized solar cells (DSSCs). The crystal structure and morphology analyses of as-prepared MoS2-rGO hybrids indicated the presence of MoS2 nanostructures having a petal-like morphology on rGO sheets. Raman spectroscopy provided evidence for weak Van der Waals interactions between MoS2 and rGO layers along with a low defect density. DSSCs made with counter electrodes (CEs) of MoS2-rGO hybrids, showed an impressive power conversion efficiency of 7.83% surpassing the DSSCs with CEs of pristine MoS2 (5.97%) and the conventional Pt (7.57%). The cyclic voltammetry and electrochemical impedance studies have shown that the incorporation of reduced graphene oxide in the MoS2 nanostructures significantly decreased the charge transfer resistance and improved the electrocatalytic activity of their CEs. This is partly attributed to the morphology of the hybrid in which the petal-like MoS2 nanostructures on the rGO sheets provided numerous catalytic sites, which, in turn, enhanced the charge transfer across the CE providing a synergistically high performance. These results have indicated that the MoS2-rGO hybrids are promising alternatives to the conventional Pt-based CEs in DSSCs.

Electrically conducting Au-multiwalled carbon nanotube/polyaniline (Au-MWCNT/PANi) nanocomposites were synthesized by two different ways: (1) by direct mixing of MWCNT/PANi and Au nanoparticles (Au-MWCNT/PANi-1) and (2) by in situ polymerization of aniline in the presence of both MWCNTs and Au nanoparticles (Au-MWCNT/PANi-2). The higher electrical conductivity of Au-MWCNT/PANi-2 compared with the other samples (PANi, MWCNT/PANi, Au-MWCNT/PANi-1) is supported by the red shifts of the UV-vis bands (polaron/bipolaron), the high value of the –NH+= stretch peak (Fourier transform infrared spectroscopy studies), the high % crystallinity (X-ray diffraction analysis) and more uniform dispersion of the Au NPs in the material. The performance of the samples in electromagnetic interference (EMI) shielding and microwave absorption was studied in the X-band (8–12 GHz). For all the samples, absorption was the dominant factor contributing toward the EMI shielding. Au-MWCNT/PANi-2 showed the best performance with a total shielding effectiveness of −16 dB [averaged over the X-band (GHz)] and a minimum reflection loss of −56.5 dB. The higher dielectric properties resulting from the heterogeneities because of the presence of nanofillers and the high electrical conductivity lead to the increased EMI shielding and microwave absorption. The results show the significance of both Au nanoparticles and method of synthesis on the EMI shielding performance of MWCNT/PANi composites. Copyright © 2016 John Wiley & Sons, Ltd.

A water-soluble and biocompatible polymer, i.e. biotinylated poly(vinyl alcohol)-grafted graphene oxide (GO), was used as a nanocarrier for targeted delivery of anticancer drug camptothecin (CPT). The extent of CPT release in the presence of glutathione (GSH) from GO–biotinPVA–CPT was monitored by the increase in the fluorescence intensity, at λmax = 450 nm. The cell-specific (HeLa) antiproliferative activity of GO–biotinPVA–CPT makes it suitable to be used for targeted delivery of chemotherapeutics to cancerous cells.

Herein, we have developed a simple and facile technique at 210 °C to obtain nano-structured organic compounds, instead of making carbon dots at a relatively higher temperature. Taking the advantage of stable dispersion of organic nanostructures in an aqueous medium, composite of polyaniline has been developed and subsequently utilized as an active electrode material for supercapacitor application. This composite material confirms noteworthy enhancement in specific capacitance (779 F/g) and also divulges the attractive capacitance retention using three-electrode systems. The suitability of the materials for the solid-state device was tested with a prototype two-electrode device. The symmetric device exhibits 130 F/g gravimetric capacitance and 650 mF/cm2 areal capacitance. The improved performance in the specific capacitance is observed due to the generation of more active charge storage sites in the interfacial interaction of organic nanostructures and polyaniline in the composite. The cyclic stability of the symmetric device reveals excellent retention of 96% in specific capacitance over 5000 cycles.

Cold spray deposition of micro-particles using a supersonic nozzle is studied using the numerical simulation of the turbulent flow field. A bell-type nozzle geometry is used for injecting the cold particle spray at supersonic velocity. The impact of driver gas pressure, temperature and particle size on critical deposition parameters is studied for transverse and axial injection. The results of the study show that particle velocity at impact is higher for axial injection in comparison to that for transverse injection under similar conditions. The approach of utilizing bell type nozzles for spray deposition is found to be beneficial with regard to the compactness of the system as well as the axial alignment of the spray.

In this present study, a highly conductive thermally reduced graphene oxide (TRGO) was synthesized by a low temperature thermal reduction method using RF heating, under an argon-hydrogen atmosphere. The crystallinity and morphology were examined by X-ray diffraction, Raman spectroscopy and TEM analysis. The chemical structure including the functional groups present on TRGO was studied using X-ray photoelectron spectroscopy and FTIR analysis. The studies reveal that thermal reduction of graphene oxide was successful under the experimental conditions and that the TRGO had high crystallinity. Further, the performance of the as-prepared TRGO was tested as a counter electrode (CE) in a dye-sensitized solar cell (DSSC). The maximum power conversion efficiency (PCE) obtained was 4.86% for TRGO under one sun illumination, which is comparable to that of a platinum CE-based DSSC (5.24%). The electrocatalytic activity and electron transfer kinetics were examined by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and Tafel measurements. The series resistance (Rs) and charge transfer resistance (Rct) values were found to be 35.4 Ωcm-2 and 56.40 Ωcm-2 for TRGO. The results reveal that the TRGO had an electrocatalytic performance similar to that of Pt, making TRGO-CEs promising alternatives to the conventional Pt-CEs in DSSCs.

MoS2 thin films with marigold flower-like nanostructures were grown on conductive fluorine-doped tin oxide (FTO) substrates through a one-step hydrothermal synthesis for their application as counter electrodes (CEs) in dye-sensitized solar cells (DSSCs). Different MoS2 thin film samples (A-D) were grown on FTO slides using different concentrations of precursors (sodium molybdate and thioacetamide), while keeping the Mo/S molar ratio constant (1:4.6), in all samples. The effect of varying precursor concentrations (3.2-12.6 mM on MoS2 basis) on the structure of the nanostructured thin films and their performance as DSSC-CEs was investigated. Scanning electron microscopy revealed a material with an infolded petal-like morphology. With increasing precursor concentration, the petal-like structures tended to form bunched nanostructures (100-300 nm) resembling marigold flowers. X-ray diffraction analysis, X-ray photoelectron, and Raman spectroscopy studies showed that the thin films were composed of hexagonal MoS2 with good crystallinity. Hall effect measurements revealed MoS2 to be a p-type semiconductor with a carrier mobility of 219.80 cm(2) V-1 s(-1) at room temperature. The electrochemical properties of the thin films were examined using cyclic voltammetry and electrochemical impedance spectroscopy. The marigold flower-like MoS2 thin films showed excellent electrocatalytic activity towards the I-/I-3(-) reaction and low charge transfer resistance (R-ct) values of 14.77 Omega.cm(-1), which was close to that of Pt electrode (12.30 Omega. cm(-1)). The maximum power conversion efficiency obtained with MoS2 CE-based DSSCs was 6.32%, which was comparable to a Pt CE-based DSSC (6.38%) under one sun illumination. Similarly, the maximum incident photon-to-charge carrier efficiency exhibited by MoS2 CE-based DSSCs was 65.84%, which was also comparable to a Pt CE-based DSSC (68.38%). The study demonstrated that the marigold flower-like nanostructured MoS2 films are a promising alternative to the conventional Pt-based CEs in DSSCs.

This work reports a graphene-based nonenzymatic electrochemical sensing platform for the detection of dopamine (DA), uric acid (UA), and ascorbic acid (AA). Graphene oxide, synthesized by modified Hummers method, was thermally reduced in an induction furnace at 200 °C in an Ar-H2 atmosphere to obtain thermally reduced graphene oxide (tRGO). Nanocomposites of tRGO-TiO2 were obtained by a hydrothermal method, and were characterized using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and X-ray diffraction (XRD). FTIR spectra showed Ti-O-C peaks, indicating covalent linkage between the TiO2 nanoparticles and the reduced graphene oxide sheets. Glassy carbon electrode (GCE) was modified with the nanocomposite (tRGO-TiO2-GCE), and the modified electrode could detect dopamine (DA: 1 to 1000 µM), uric acid (UA: 1 to 900 µM), and ascorbic acid (AA: 10 to 1000 µM) in each other's presence over wide ranges, with adequate separation in peak potentials. Differential pulse voltammetry experiments yielded linear responses with sensitivities of 133.18, 33.96, and 155.59 µA mM(-1) cm(-2) for DA, UA, and AA, respectively.

Calcium oxide is an effective carbon dioxide absorbent, but the cyclic lifetime and durability of the absorbent are key issues for its practicability. When used as pellets, pore plugging and sintering of particles have been found to be the major causes of the degradation of the absorption capacity in cyclic operation. In order to minimize these adverse effects, a simple and effective immobilization technique of the calcium oxide on fibrous ceramic-based fabrics (alumina and yttria) was developed. The prepared samples were characterized and evaluated by various analytical and experimental tools comprehensively. For a sample with 23 wt.% calcium oxide on the alumina fabric, continuous cyclic carbonation conversions of about 75% were achieved over 13 carbonation–calcination cycles under mild calcination condition at 750 °C and no CO2 in N2. Under more severe calcination condition at 850 °C and 20 wt.% CO2 in N2, the yttria fabric proved superior to alumina as a substrate of calcium oxide for carbon dioxide capture and the reactivity of the calcium oxide absorbent using the yttria fabric was maintained at the same level for 12 cycles.

Platinum nanoparticle-decorated graphene and carbon nanotube (Pt–Gr–CNT) nanocomposites were synthesized by radio frequency chemical vapor deposition (RF-CVD) from ethanol, using a Pt/MgO catalyst. Morphological analysis showed Pt nanoparticles decorating graphene sheets and double-walled and multiwalled carbon nanotubes. It was observed that, upon encountering Pt nanoparticles, carbon nanotubes unravelled into graphene sheets. This may be due to graphitic carbon atoms from growing CNTs forming bonds with carbon atoms from other CNTs, particularly at the site of another Pt NP. The Pt–Gr–CNT-modified GCE showed high electrocatalytic activity towards the oxidation of ascorbic acid (AA), dopamine (DA) and uric acid (UA) in 0.1 M phosphate buffer solution (pH 7.0) in cyclic voltammetry (CV) and differential pulse voltammetry (DPV) studies. CV showed well-separated oxidation peaks of AA (−99 mV), DA (121 mV) and UA (261 mV). In DPV studies, the peak separation between AA–DA, DA–UA and AA–UA was 210 mV, 140 mV and 360 mV respectively. The simultaneous detection of AA, DA and UA using DPV, in respective concentration ranges of 200–900 μM, 0.2–30 μM, 0.1–50 μM, showed good linearity and sensitivities of 0.186 μA μM−1 cm−2 (AA), 9.199 μA μM−1 cm−2 (DA) and 9.386 μA μM−1 cm−2 (UA) respectively. The Pt–Gr–CNT/GCE was evaluated for the simultaneous detection of the three biomolecules in real sample solutions of a vitamin C tablet, human serum and urine. It showed recoveries in the range of 93–101%, indicating that it is a promising platform for further biosensor development.

Nanofiber composites (Polyimide/f-SWCNT) of Pyromellitic dianhydride, 4,4'-Oxydianiline, and 4,4'-(4,4'-isopropylidene diphenyl-1,1'-diyl dioxy) dianiline (PMDA-ODA/IDDA) and surface-functionalized single walled carbon nanotubes (f-SWCNT) were made by electrospinning a solution of poly(amic acid) (PAA) containing 0-2 wt% f-SWCNT followed by thermal imidization. X-ray photoelectron spectroscopy spectra verified the oxidation of SWCNT surface after acid treatment, and indicated possible hydrogen bonding interactions between the f-SWCNTs and polyamic acid. High-resolution scanning electron microscopy images showed the average diameter of nanofibers to be below 150 nm, and transmission electron microscopy images showed that SWCNTs were aligned inside the polymer nanofiber. In thermogravimetric analysis, all composites showed increased thermal stability with increasing f-SWCNT content compared to neat PI. Storage modulus also increased from 124 MPa to 229 MPa from neat PI to 2% f-SWCNT composite.

Multiwalled carbon nanotubes (MWCNTs) were synthesized by RF (radio frequency) heating at 850°C using an MgO-supported bimetallic Fe–Mo catalyst. Ethanol was used as the carbon source. The MWCNTs were tested using Raman spectroscopy, high-resolution transmission electron microscopy (HRTEM), and thermogravimetric analysis (TGA). HRTEM studies show nanotubes with an average diameter of 16.0 ± 3.5 nm. In Raman spectroscopy, the ratios of intensities of the G and D band and the 2D and G bands were 0.90 and 0.47, respectively. These ratios are generally indicative of high crystallinity and purity of the MWCNTs. The purity of MWCNTs was calculated from TGA analysis.

Two different azo molecules functionalized graphene oxide (GO) through an ester linkage have been synthesized for the first time. Chemical structure of the azo-GO hybrids was confirmed by Fourier transform infrared spectroscopy and UV-visible spectroscopy. The GO functionalized with 5-((4-methoxyphenyl)azo)-salicylaldehyde was further characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM). The SEM studies demonstrated that the morphology of the azo-GO hybrid was found to be similar to the GO sheets but slightly more wrinkled. Further, TEM image of azo-GO indicates some dark spots on the GO sheets due to azo functionalization. AFM results also reveal that the azo functionalization increases the thickness of GO sheet to 4–5 nm from 1.2–1.8 nm. Both the azo-hybrids show absorption band around 379 nm due to the π–π* transition of the trans azo units. Photoluminescence spectra of azo-GO hybrids show a strong quenching compared with azo molecules due to the photoinduced electron or energy transfer from the azo chromophore to the GO sheets. It also reveals strong electronic interaction between azo and GO sheets.

Hexagon-shaped bismuth nano- and micro-architectures have been electrodeposited onto polycrystalline copper electrodes from a nitrate bath at both constant current and constant potential conditions. Hexagonal geometries of varying sizes are obtained by tuning the deposition rate vis-a-vis that of a competing reaction, nitrate reduction. Nano-hexagons (100 nm to 1 μm) are obtained at 10 mA cm−2 when the HNO3 concentration is 0.2 M or less, and with 0.4 M HNO3, hexagons of sizes up to 20 μm are deposited. The obtained hexagons are polycrystalline. Further increase in nitric acid concentration results in fused sheet-like morphologies. Increasing bismuth concentration or reducing current density results in large crystallites. The ability of the obtained bismuth morphologies to detect ultratrace levels of lead has been studied. Only the nanohexagons and crystallites are able to detect lead at 1 ppb. The nanohexagons show good sensitivity to the detection of lead (LoD: 0.05 ppb or 0.24 nM; sensitivity: ~0.75 μA ppb−1) using Square-Wave Anodic Stripping Voltammetry (SWASV), and clearly distinct peaks for Pb2+, Zn2+, and Cd2+, indicating the potential for this morphology as an electrocatalytic material.

Three polymers were used in the preparation of three-component nanocomposites. Sulphonated poly(ether-ether-ketone) (SPEEK) was synthesized by sulphonation of powdered poly(ether-ether-ketone) (PEEK) using concentrated sulphuric acid. Polyvinyl alcohol (PVA) was used as purchased. Polyaniline (PANI) was synthesized using aniline, hydrochloric acid and ammonium persulphate. Three nanocomposite films based on SPEEK, PVA and PANI were synthesized through solution casting from N-Methyl-2-pyrrolidone (NMP) solutions with a magnetic filler, iron tungstate (FeWO4) and a conductive filler, reduced graphene oxide (RGO) dispersed in them. The synthesized PANI was characterized by X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) and the nanocomposites (RGO/PANI, FeWO4/PANI, FeWO4-RGO/PANI) were characterized by FTIR, TGA, DSC and SEM. The nanocomposite films based on SPEEK and PVA containing 2% RGO and 2% FeWO4 showed the electromagnetic interference (EMI) reflection loss of only -0.5 dB for a 0.1 mm thick sample. The PANI based nanocomposite film containing 2% RGO and 2% FeWO4 showed the maximu m EMI reflection loss of -4.5 dB for a 0.1mm thick sample.

A CQD-polypyrrole composite was developed as a supercapacitor electrode material. Carbon quantum dots (CQDs) were synthesized using citric acid as carbon precursor. The CQDs were incorporated in a polypyrrole matrix by dispersing them during the in-situ polymerization of pyrrole. The structure and morphology of the composite were characterized using FT-IR, XRD, TEM. Cyclic voltammetry and galvanostatic charge-discharge studies were performed using a three-electrode system to understand the electrochemical behaviour of the sample. The composite showed a 33% increase in the specific capacitance as compared to neat polypyrrole.

The electrical conductivity and yield of polyaniline (PANi) were optimized using a design of experiments (DOE). PANi samples were synthesized by the chemical oxidative polymerization of aniline using methane sulfonic acid as the dopant acid and ammonium persulfate as the oxidant. The main factors in the synthesis of PANi that can affect the conductivity were identified as (i) the concentration of dopant acid, (ii) oxidant-to-monomer ratio, and (iii) the addition rate of oxidant to monomer. Using a Box-Behnken DOE method the regression equation, main effects plots, contour plots, and optimization plots for conductivity and yield were generated and analyzed. Under the optimized conditions of dopant acid concentration of 0.9M, an oxidant addition rate of 30 mL/h and an OM ratio of 0.9, PANi with a conductivity of 1.95 S/cm and yield of 95% was obtained. The observed trends in the four-point probe conductivity measurements were correlated with the polymer structure using fourier transform infrared spectroscopy, X-ray diffraction studies, and scanning electron microscopy. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1047-1057, 2013

A novel technique for synthesis of thin-layered graphene sheets (GNS) were established by hydrogen-induced reduction of graphene oxide at low temperature of 200°C, using radio frequency chemical va...

Graphical abstract: Fiber with porous like structure of PANI/SnO{sub 2} nanocomposites were prepared by simplest in situ chemical polymerization method. The PL emission spectra revealed that the band from 404 and 436 nm which is related with oxygen vacancies. The excellent electrochemical properties of composite electrode show the specific capacitance of 173 F/g at a scan rate of 25 m V/s. Display Omitted Highlights: ► Self assembled PANI/SnO{sub 2} nanocomposites were synthesized by simple polymerization method. ► Electrochemical behavior of PANI/SnO{sub 2} nanocomposites electrode was analyzed by CV. ► Nanocomposites exhibit a higher specific capacitance of 173 F/g, compared with pure SnO{sub 2}. -- Abstract: Polyaniline (PANI)/tin oxide (SnO{sub 2}) fibrous nanocomposites were successfully prepared by an in situ chemical polymerization method with suitable conditions. The obtained composites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy, photoluminescence (PL), electrical conductivity and cyclic voltammetry studies (CV). The XRD pattern of the as-prepared sample shows the presence of tetragonal SnO{sub 2} and the crystalline structure of SnO{sub 2} was not affected with the incorporation of PANI. The FTIR analysis confirms the uniform attachment of PANI on the surface of SnO{sub 2} nanostructures. SEM images show amore » fibrous agglomerated structure of PANI/SnO{sub 2}. The PL emission spectra revealed that the band from 404 and 436 nm which is related with oxygen vacancies. The electrochemical behavior of the PANI/SnO{sub 2} composite electrode was evaluated in a H{sub 2}SO{sub 4} solution using cyclic voltammetry. The composite electrode exhibited a specific capacitance of 173 F/g at a scan rate 25 mV/s. Thus the as-prepared PANI/SnO{sub 2} composite shows excellent electrochemical properties, suggesting that this composite is a promising material for supercapacitors.« less

Electrically conducting nanocomposites of polyaniline (PANI) with carbon-based fillers have evinced considerable interest for various applications such as rechargeable batteries, microelectronics, sensors, electrochromic displays and light-emitting and photovoltaic devices. The nature of both the carbon filler and the dopant acid can significantly influence the conductivity of these nanocomposites. This paper describes the effects of carbon fillers like carbon black (CB), graphite (GR) and muti-walled carbon nanotubes (MWCNT) and of dopant acids like methane sulfonic acid (MSA), camphor sulfonic acid (CSA), hydrochloric acid (HCl) and sulfuric acid (H2SO4) on the electrical conductivity of PANI. The morphological, structural and electrical properties of neat PANI and carbon–PANI nanocomposites were studied using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT–IR), UV–Vis spectroscopy and the four-point probe technique, respectively. Thermogravimetric analysis (TGA) and X-ray diffraction (XRD) studies were also conducted for different PANI composites. The results show that PANI and carbon–PANI composites with organic acid dopants show good thermal stability and higher electrical conductivity than those with inorganic acid dopants. Also, carbon–PANI composites generally show higher electrical conductivity than neat PANI, with highest conductivities for PANI–CNT composites. Thus, in essence, PANI–CNT composites prepared using organic acid dopants are most suitable for conducting applications.

Polyaniline-based nanocomposites containing carbon nanotubes (CNT), reduced graphene oxide (rGO) and mixture of CNTs and rGO were synthesized. UV-visible spectroscopy and FT-IR spectroscopy confirmed the presence of polyaniline (PANi) and carbon nanomaterials. Scanning electron microscopy revealed that the neat PANi had a granular morphology, which can lead to increased electrical resistance to high interfacial resistance between domains of PANi. Cyclic voltammetry of PANi, PANi/CNT, PANi/rGO and PANi/CNT/rGO showed that in general, specific capacitance reduces with increasing scan rate within the range (10–100 mV s−1). Also the specific capacitance values at any given scan rate within the above range, for PANi, PANi/CNT, PANi/rGO and PANi/CNT/rGO were found to be in increasing order. The specific capacitance of the PANi/CNT/rGO nanocomposite as measured by galvanostatic charge-discharge measurements, was found to be 312.5 F g−1. The introduction of the carbon nanomaterials (CNTs, rGO) in PANi in general leads to improved specific capacitance, while the addition of CNTs and rGO together leads to synergistic improvement in the specific capacitance, owing to a combination of factors.

Fe3O4 nanoparticles were synthesized by co-precipitation of ferric chloride (FeCl3) and ferrous chloride (FeCl2). Reduced graphene oxide (RGO) was prepared by reducing the graphene oxide, which was synthesized by Hummer's method, using hydrazine hydrate. Three nanocomposites based on sodium dodecyl benzene sulphonate (SDBS)-doped polyaniline were synthesized through in situ polymerization in the presence of the fillers (i) Fe3O4, (ii) reduced graphene oxide (RGO) and (iii) Fe3O4-decorated RGO respectively. The synthesized PANI and the composites were characterized by X-ray diffraction, Fourier transform infrared spectroscopy and transmission electron microscopy. Their microstructures, electrical conductivities, and EMI shielding effectiveness were studied. The nanocomposite containing 10 % RGO showed the maximum electrical conductivity and the one with 10 % RGO and 10 % Fe3O4 showed the maximum EMI shielding effectiveness of 7.5 dB for a 1 mm thick sample.

A facile method has been developed for the synthesis of a graphene quantum dots/cobalt ferrite nanocomposite. Graphene quantum dots (GQDs) were synthesized by a simple bottom-up method using citric acid, followed by the co-precipitation of cobalt ferrite nanoparticles on the graphene quantum dots. The morphology, structural analysis, optical properties, magnetic properties were investigated using transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-vis absorption spectroscopy, fluorescence spectroscopy, vibrating sample magnetometry (VSM) measurements. The synthesized nanocomposite showed good fluorescence and superparamagnetic properties, which are important for biomedical applications.

1Florida Polytechnic University, 4700 Research Way, Lakeland, FL 33805, USA 2The Polytechnic School, Ira A. Fulton Schools of Engineering, Arizona State University, Mesa, AZ 85212, USA 3Department of Chemical Engineering and Materials Science, Amrita Vishwa Vidyapeetham, Amritanagar, Coimbatore 641112, India 4United Technologies Research Corporation, 411 Silver Lane, East Hartford, CT 06118, USA 5Department of Mechanical and Aerospace Engineering, New Mexico State University, Las Cruces, NM 88003, USA

Nanofiber composites (Polyimide/f-SWCNT) of Pyromellitic dianhydride, 4,4'-Oxydianiline, and 4,4'-(4,4'-isopropylidene diphenyl-1,1'-diyl dioxy) dianiline (PMDA-ODA/IDDA) and surface-functionalized single walled carbon nanotubes (f-SWCNT) were made by electrospinning a solution of poly(amic acid) (PAA) containing 0-2 wt% f-SWCNT followed by thermal imidization. X-ray photoelectron spectroscopy spectra verified the oxidation of SWCNT surface after acid treatment, and indicated possible hydrogen bonding interactions between the f-SWCNTs and polyamic acid. High-resolution scanning electron microscopy images showed the average diameter of nanofibers to be below 150 nm, and transmission electron microscopy images showed that SWCNTs were aligned inside the polymer nanofiber. In thermogravimetric analysis, all composites showed increased thermal stability with increasing f-SWCNT content compared to neat PI. Storage modulus also increased from 124 MPa to 229 MPa from neat PI to 2% f-SWCNT composite.

This paper describes the dramatic success in the eco-restoration of a heavy-metal contaminated open garbage dump. A number of heavy metals (As, Cd, Cu, Co, Pb, Hg, Cr) were detected in the soil and river sediment at the site. The main restoration activities included mulching, surface-addition of compost and fresh soil and phytoremediation using vetiver and other plants. Within three years of the restoration activities, heavy metal concentrations in the contaminated soil reduced drastically. There was relatively low uptake of the heavy metals by the plants; however, they might have been crucially responsible for providing a favorable environment for soil-restoring microrganisms in their rhizosphere. Observable habitat-restoration continues at the site, including the return of birds and insects and other wildlife, making this an ideal site for further research and demonstration for community awareness and education.

The synthesis of a porphyrin-graphene oxide hybrid (GO-TAP) was carried out by covalently functionalizing graphene oxide (GO) with 5,10,15,20 mesotetra (4-aminophenyl) porphyrin (TAP) through an amide linkage. The GO-TAP hybrid has been charac- terized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and UV-visible spectroscopy. The peak intensity of the Soret band of the material was suppressed compared to neat TAP. This indicates a strong interaction between the electronic energy level of TAP and GO in the GO-TAP hybrid. The functionalization of GO with TAP significantly improved its solubility and dispersion stability in organic solvents. Scanning electron micrographs reveal that the hybrid was found to be similar to the unmodified GO but slightly more wrinkled. Transmission electron micrographs also demonstrate that GO sheet in the hybrid is more wrinkled with some dark spot due to functionalization. Atomic force microscopy results also reveal that the TAP functionalization increases the thickness of GO sheet to 2.0-3.0 nm from 1.2 to 1.8 nm. We observed improved nonlinear optical and optical limiting properties for the hybrid compared to both graphene oxide and porphyrin. GO-TAP shows fluo- rescence quenching compared with porphyrin, indicat- ing excellent electron and/or energy transfer to GO from TAP. Thermogravimetric analysis confirms that the GO-TAP hybrid has outstanding thermal stability.

Multiwalled carbon nanotubes with high crystallinity and purity were synthesized with acetylene as the carbon source using radio frequency catalytic chemical vapor deposition method (RF-CCVD) and a bimetallic Fe-Co catalyst supported on CaO at 720°C. The sample obtained was tested using Raman spectroscopy, high resolution transition electron microscopy (HRTEM) and thermogravimetric analysis (TGA). The Raman spectra revealed G to D band and 2D to G band intensity ratios of 0.90 and 0.54 respectively. A purity of 90% was obtained from the TGA studies. HRTEM studies further showed that the nanotubes had an average diameter of 14.7 ± 4.76nm.

Keiko M Tarquinio1, Nikhil K Kothurkar2, Dharendra Y Goswami3, Ronald C Sanders Jr4, Arno L Zaritsky5, Ann Marie LeVine61Division of Pediatric Critical Care Medicine, Department of Pediatrics, Rhode Island Hospital, The Warren Alpert Medical School, Brown University, Providence, RI USA; 2Department of Chemical Engineering and Materials Science, Amrita School of Engineering, Ettimadai, Coimbatore, India; 3Clean Energy Research Center, University of South Florida, Tampa, FL, USA; 4Section of Pediatric Critical Care, Department of Pediatrics, College of Medicine, University of Arkansas for Medical Sciences, Arkansas Children’s Hospital, Little Rock, AR, USA; 5Executive Medical Director, Children’s Hospital of The King’s Daughters, Norfolk, VA, USA; 6Pediatric Critical Care Medicine, University of Michigan Medical School, C.S. Mott Children’s Hospital, Ann Arbor, MI, USAPurpose: Ventilator-associated pneumonia (VAP) is a nosocomial infection resulting in significant morbidity and mortality. Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) are pathogens associated with VAP. Silver (Ag) coating of endotracheal tubes (ETTs) reduces bacterial colonization, however titanium dioxide (TiO2) coating has not been studied.Methods: Five types of ETT coatings were applied over silica layer: Ag, solgel TiO2, solgel TiO2 with Ag, Degussa P25 TiO2 (Degussa TiO2), and Degussa TiO2 with Ag. After ETTs were incubated with P. aeruginosa or S. aureus; colonization was determined quantitatively.Results: Pseudomonas aeruginosa and S. aureus grew for 5 days on standard ETTs. Compared to standard ETTs, P. aeruginosa growth was significantly inhibited by solgel TiO2 with Ag at 24 hours, and by Degussa TiO2 with Ag at 24 and 48 hours after inoculation. No significant difference in S. aureus growth was observed between the control and any of the five coatings for 5 days.Conclusion: In vitro, solgel TiO2 with Ag and Degussa TiO2 with Ag both attenuated P. aeruginosa growth, but demonstrated no effect on S. aureus colonization. Further studies using alternative coating and incorporating UV light exposure are needed to identify their potential utility in reducing VAP.Keywords: ventilator-associated pneumonia, Degussa titanium dioxide, solgel titanium dioxide, quantitative culture

Anthropogenic carbon dioxide emission from its sources must be reduced to decrease the threat of global warming. Calcium oxide is considered as an effective carbon dioxide absorbent in biomass or coal gasification process as well as conventional power plants. It reacts with carbon dioxide to form calcium carbonate which can be decomposed into the original oxide and carbon dioxide at high temperature by calcination. In order to make this method practical for the carbon dioxide capture and sequestration, the performance of the calcium oxide absorbent must be maintained over a large number of carbonation/calcination cycles. For this reason, loss in the surface area of the absorbent due to pore plugging and sintering of particles in cyclic operation must be avoided. To prevent or minimize this problem, a simple and effective procedure for immobilization of calcium oxide on a fibrous alumina mat was developed in this study. The prepared samples were observed by SEM and the cyclic performance of the calcium oxide absorbent was evaluated by TGA experiments and compared to the previous studies in literature. 75% and 62% maximum carbonation conversions of the prepared absorbents with 23 wt % and 55 wt % calcium oxide content were achieved respectively and remained stable even after ten cycles whereas conversion in the literature data dropped steeply with the number of cycles.Copyright © 2008 by ASME

UT-3 thermochemical hydrogen production cycle has been studied, both theoretically and experimentally, and is one of the very few cycles studied on a pilot plant scale. The maximum operating temperature in this cycle is relatively lower than the temperatures in other cycles. Another advantage of this cycle is that it is comprised of four gas-solid reactions which simplify product separation. Although the cycle has several such advantages, one of the significant issues is the development of solid reactants that are chemically reactive and physically stable in cyclic operations between oxide and bromide forms, which have considerably different molar volumes. Acceleration of reaction rate as well as longer cyclic life time and durability of the solid reactant are important keys for the practicability of the cycle. Additionally, a simpler preparation step of the reactant is preferable. Therefore, in order to increase the surface area of the calcium oxide reactant and maintain reactivity as well as structure in cyclic transformations, porous calcium oxide films have been examined as candidates. The calcium oxide precursor was prepared by sol-gel chemistry following a metal alkoxide process and the film was fabricated by a dip coating procedure. The characterization of the calcium oxide film such as the structural changes in the film and compositional conversions due to the bromination reaction has been performed using SEM and EDS. Based on a preliminary experimental analysis as well as the advantages of a film type reactant, one can conclude that the calcium oxide film may be a feasible alternative to a pellet-type reactant.