Photocatalytic degradation of gaseous toluene by using immobilized titania/silica on aluminum sheets

The aim of this study was to prepare a highly active immobilized titania/silica photocatalyst and to test its performance in situ toward degradation of toluene as one of the major toxic indoor contaminants. In this work, two different titania layers immobilized on Al sheets were synthesized via low temperature sol-gel method employing presynthesized highly active titania powders (Degussa P25 and Millennium PC500, mass ratio 1:1): (a) with a silica/titania binder and a protective layer and (b) without the binder. The photocatalysts were characterized by X-ray diffraction, nitrogen sorption measurements, scanning electron microscopy (SEM), infrared spectroscopy, and UV-vis diffuse reflectance spectroscopy (DRS). The in situ photocatalytic degradation of gaseous toluene was selected as a probe reaction to test photocatalytic activity and to verify the potential application of these materials for air remediation. Results show that nontransparent highly photocatalytically active coatings based on the silica/titania binder and homogeneously dispersed TiO2 powders were obtained on the Al sheets. The crystalline structure of titania was not altered upon addition of the binder, which also prevented inhomogeneous agglomeration of particles on the photocatalyst surface. The photoactivity results indicate that the adsorption properties and photocatalytic activity of immobilized photocatalysts with the silica/titania binder and an underlying protective layer were very effective and additionally, they exhibited considerably improved adhesion and uniformity. We present a new highly photocatalytically active immobilized catalyst on a convenient metallic support, which has a potential application in an air cleaning device.

Development of high performance electroless Ni-P-HNT composite coatings

Halloysite nanotubes (HNTs) of the dimension 50nm x 1-3 mu m (diameter x length) are utililized to fabricate the alloy composite by employing electroless/autocatalytic deposition technique. Electroless Ni-P-HNT binary alloy composite coatings are prepared successfully on low carbon steel. These nanotubes were made to get inserted/incorporated into nickel matrix and corresponding composites are examined for their electrochemical, mechanical and tribological performances and compared with that of plain Ni-P. The coatings were characterized using scanning electron microscopy (SEM) and Energy dispersive X-ray analysis (EDX) techniques to analyze surface nature and composition correspondingly. Small amount of incorporated HNTs made Ni-P deposits appreciable enhancement and betterment in corrosion resistance, hardness and friction resistance. This drastic improvement in the properties reflects the effect of addition of HNTs into Ni-P matrix leading to the development of high performance Ni-P-HNT composite coatings. (C) 2012 Elsevier B. V. All rights reserved.

Low dimensional fabrication of giant dielectric CaCu3Ti4O12 through soft e-beam lithography

We report low-dimensional fabrication of technologically important giant dielectric material CaCu3Ti4O12 (CCTO) using soft electron beam lithographic technique. Sol-gel precursor solution of CCTO was prepared using inorganic metal nitrates and Ti-isopropoxide. Employing the prepared precursor solution and e-beam lithographically fabricated resist mask CCTO dots with similar to 200 nm characteristic dimension were fabricated on platinized Si (111) substrate. Phase formation, chemical purity and crystalline nature of fabricated low dimensional structures were investigated with X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS) and selected area electron diffraction (SAED), respectively. Morphological investigations were carried out with the help of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). This kind of solution based fabrication of patterned low-dimensional high dielectric architectures might get potential significance for cost-effective technological applications. (C) 2012 Elsevier B.V. All rights reserved.

Na0.33V2O5 center dot 1.5H(2)O nanorings/nanorods and Na0.33V2O5 center dot 1.5H(2)O/RGO composite fabricated by a facile one pot synthesis and its lithium storage behavior

In this work, Na0.33V2O5 center dot 1.5H(2)O nanorings/nanorods and Na0.33V2O5 center dot 1.5H(2)O/reduced graphene oxide (RGO) composites have been prepared through a facile hydrothermal route in acidic medium at 200 degrees C for 2 days. The hydrothermally derived products have been characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, UV-Visible spectroscopy, Thermogravimetric analysis (TGA), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM) and electrochemical discharge-charge cycling in lithium ion battery. XRD pattern exhibits the layered structure of Na0.33V2O5 center dot 1.5H(2)O and the composite shows the presence of RGO at 2 theta = 25.8 degrees. FTIR spectrum shows that the band at 760 cm(-1) could be assigned to a V-OH2 stretching mode due to coordinated water. Raman spectrum shows that the band at 264 cm(-1) is due to the presence of water molecules between the layers. FESEM/TEM micrographs reveal that the products consist of nanorings of inner diameter 5 mu m and thickness of the ring is found to be 200-300 nm. Addition of exfoliated graphene oxide (EGO) destroys the formation of rings. The reduction of EGO sheets into RGO is also evidenced by the red shift of the absorbance peak from 228 nm to 264 nm. In this composite Na0.33V2O5 center dot 1.5H(2)O nanorods may adhere to the surface of RGO and/or embedded in the RGO nanosheets. As a result, an effective three-dimensional conducting network was formed by bridging RGO nanosheets, which can facilitate electron transport effectively and thus improve the kinetics and rate performance of Na0.33V2O5 center dot 1.5H(2)O nanorings/nanorods. The Na0.33V2O5 center dot 1.5H(2)O/RGO composites exhibited a discharge capacity of 340 mAh g(-1) at a current density of 0.1 mA g(-1) and also an improved cyclic stability. RGO plays a `flexible confinement' function to enwrap Na0.33V2O5 center dot 1.5H(2)O nanorods, which can compensate for the volume change and prevent the detachment and agglomeration of pulverized Na0.33V2O5 center dot 1.5H(2)O, thus extending the cycling life of the electrode. A probable reaction mechanism for the formation of Na0.33V2O5 center dot 1.5H(2)O nanorings is also discussed. (C) 2012 Elsevier B.V. All rights reserved.

CdSiO3:Pr3+ nanophosphor: Synthesis, characterization and thermoluminescence studies

A series of Pr3+ (1-9 mol%) doped CdSiO3 nanophosphors have been prepared for the first time by a low temperature solution combustion method using oxalyldihydrizide (ODH) as a fuel. The final product was characterized by Powder X-ray diffraction (PXRD), Fourier Transform Infrared Spectroscopy (FTIR), scanning electron microscopy (SEM), and UV-Vis spectroscopy. The average crystallite size was calculated using Debye-Scherrer's formula and Williamson-Hall (W-H) plots and found to be in the range 31-37 nm. The optical energy band gap (E-g) of undoped for Pr3+ doped samples were estimated from Tauc relation which varies from 5.15-5.36 eV. Thermoluminescence (TL) properties of Pr3+ doped CdSiO3 nanophosphor has been investigated using gamma-irradiation in the dose range 1-6 kGy at a heating rate of 5 degrees C s(-1). The phosphor shows a well resolved glow peak at similar to 171 degrees C along with shouldered peak at 223 degrees C in the higher temperature side. It is observed that TL intensity increase with increase of Pr3+ concentration. Further, the TL intensity at 171 degrees C is found to be increase linearly with increase in gamma-dose which is highly useful in radiation dosimetry. The kinetic parameters such as activation energy (E), frequency factor (s) and order of kinetics was estimated by Luschiks method and the results are discussed. (c) 2012 Elsevier B.V. All rights reserved.

Vaporization dynamics of functional droplets in a hot laminar air jet

The vaporization characteristics of pendant droplets of various chemical compositions (like conventional fuels, alternative fuels and nanosuspensions) subjected to convective heating in a laminar air jet have been analyzed. Different heating conditions were achieved by controlling the air temperature and velocity fields around the droplet. A hybrid timescale has been proposed which incorporates the effects of latent heat of vaporization, saturation vapor pressure and thermal diffusivity. This timescale in essence encapsulates the different parameters that influence the droplet vaporization rate. The analysis further permits the evaluation of the effect of various parameters such as surrounding temperature, Reynolds number, far-field vapor presence, impurity content and agglomeration dynamics (nanosuspensions) in the droplet. Flow visualization has been carried out to understand the role of internal recirculation on the vaporization rate. The visualization indicates the presence of a single vortex cell within the droplet on account of the rotation and oscillation of the droplet due to aerodynamic load. External heating induced agglomeration in nanofluids leads to morphological changes during the vaporization process. These morphological changes and alteration in vaporization behavior have been assessed using high speed imaging of the diameter regression and Scanning Electron Microscopy images of the resultant precipitate. (C) 2012 Elsevier Ltd. All rights reserved.

PEO|Sncl(2)|PANI composites: as an electrolyte in solid-state battery

Solid-state polymer electrolytes possess high conductivity and have advantages compared with their liquid counterparts. The polyethylene oxide (PEO)-based polymer is a good candidate for this purpose. The PEO/SnCl2/polyaniline composite (PSP composites) at different weight percentages were prepared in anhydrous acetonitrile media. Structural studies were carried out of the prepared composites by X-ray diffraction, Fourier transmission infrared spectroscopy, and surface morphology by scanning electron microscopy. The sigma (dc) was carried out by a two-probe method, and it is found that the conductivity increases with an increase in temperature. The temperature-dependent conductivity of the composites exhibits a typical semi-conducting behavior and hence can be explained by the 1D variable range hopping model proposed by Mott. The electrochemical cell parameters for battery applications at room temperature have also been determined. The samples are fabricated for battery application in the configuration of Na: (PSP): (I-2 + C + sample), and their experimental data are measured using Wagner's polarization technique. The cell parameters result in an open-circuit voltage of 0.83 V and a short-circuit current of 912 mu A for PSP (70:30:10) composite. Hence, these composites can be used in polymer electrolyte studies.

Synthesis and characterization of nickel/barium hexa-aluminate composite coatings

Electrodeposition of nickel/barium hexa-aluminate (Ni/BHA) composite coatings has been carried out from a Watt's bath on mild steel substrate. BHA powders with plate habit were synthesized by solution combustion synthesis followed by heat treatment to ensure complete conversion to the hexa-aluminate phase. Heat treated material was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) combined with X-ray analysis. The dispersion behaviour and stability of BHA suspensions with cationic and anionic surfactants at room temperature were studied by dynamic light scattering under different pH. The influence of BHA concentration in the electrolytic bath, deposition temperature, pH, current density and duty cycle on particle incorporation in the coatings were studied and conditions for maximum particle incorporation were established. Coatings with a roughness of about 0 center dot 4 mu m were produced by using this technique. Effect of BHA content on microhardness was also investigated. A reasonably good thickness of the coatings was achieved in a given set of conditions.

Reactivities of Modified and Unmodified Exfoliated Graphite Electrodes in Selected Redox Systems

The electrochemical profiles of exfoliated graphite electrodes (EG) and glassy carbon electrodes (GCE) were recorded using cyclic voltammetry and square wave voltammetry in the presence of various supporting electrolytes and Fe(CN)(6)](3-/4-), Ru(NH3)(6)](2+/3+), ferrocene redox probes. In the supporting electrolytes (KCl, H2SO4, NaOH, tetrabutylammoniumtetraflouroborate, phosphate buffers), the potential windows of EG were found in some cases to be about 200 mV larger than that of GCE. The electroactive surface area of EG was estimated to be 19.5 % larger than the GCE which resulted in higher peak currents on the EG electrode. Furthermore, EG was modified with various nanomaterials such as poly (propylene imine) dendrimer, gold nanoparticles, and dendrimer-gold nanoparticles composite. The morphologies of the modified electrodes were studied using scanning electron microscopy and their electrochemical reactivities in the three redox probes were investigated. The current and the reversibility of redox probes were enhanced with the presence of modifiers in different degrees with dendrimer and gold nanoparticles having a favorable edge.

Synthesis and structural characterization of two-dimensional hierarchical covellite nano-structures

We report a simple, template free and low-temperature hydrothermal reaction pathway using Cu(II) - thiourea complex (prepared in situ from copper (II) chloride and thiourea as precursors) and citric acid as complexing agent to synthesize two-dimensional hierarchical nano-structures of covellite (CuS). The product was characterized with the help of X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive analysis of X-ray spectroscopy (EDAX) and X-ray photoelectron spectroscopy (XPS). The concentration of citric acid in the hydrothermal precursor solution was seen to have a profound effect on the nanostructure of the product generated. Based on the outcoming product nano-architecture at different concentration of the ionic surfactant in the hydrothermal precursor solution a possible mechanism suited for reaction and further nucleation is also discussed. (C) 2012 Elsevier B.V. All rights reserved.

Synthesis of zero valent iron nanoparticles and application to removal of arsenic(III) and arsenic(V) from water

Recently nano scale zero valent iron particles (nZVI) have been considered as smart adsorbent for environmental and groundwater remediation. Although several synthetic methods are available for the preparation of nZVI, air stable nZVI are not available for remediation works. Further, challenges demand synthesis of nZVI without stabilizers and capping agents. A modified methodology for the synthesis of air stable nZVI has been developed without any capping agents and characterized by powder X-Ray Diffraction (XRD), Scanning Electron Microscopy Energy-dispersive X-Ray (SEM-EDS), Transmission Electron Microscopy (TEM) and X-Ray Photoelectron Spectroscopy (XPS). The results of the present study suggest that the synthetic nZVI are air-stable over a period of one year and consists of particles of 30-40 nm in diameter. Although a layer of less than 3 am thick oxide/hydroxide is observed by TEM and XPS, it appears to be due to oxidation of outer surface during analysis. Adsorption study has shown that the synthetic nZVI are more effective adsorbent than the commercial nZVI and can remove simultaneously arsenite As-III] and arsenate As-V] from water without prior reduction of As-V to As-III. The removal process is adsorptive rather than precipitative and the removal of As-III is greater than that of As-V.

Synthesis and characterization of nano CoFe2O4 by low‐temperature combustion synthesis using different fuels

The combustion synthesis has been utilized to prepare nanophased powders of cobalt spinel ferrite using ODH and glycine fuels. The product was characterized by X‐ray diffraction; Fourier transformed spectroscopy, scanning electron microscopy, UV‐Vis absorption etc. The XRD patterns reveal spinal cubic structure. SEM profiles show the product is porous, agglomeration, irregular in shape. The crystallite size was estimated using Scherer’s formula and W‐H plots and show nano in size (13 nm: ODH & 36 nm: Glycine). The UV‐Vis absorption shows at ∼430 nm in both the samples.

Novel low-temperature growth of SnO2 nanowires and their gas-sensing properties

A simple thermal evaporation method is presented for the growth of crystalline SnO2 nanowires at a low substrate temperature of 450 degrees C via an gold-assisted vapor-liquid-solid mechanism. The as-grown nanowires were characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction, and were also tested for methanol vapor sensing. Transmission electron microscopy studies revealed the single-crystalline nature of the each nanowire. The fabricated sensor shows good response to methanol vapor at an operating temperature of 450 degrees C. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

A method of designing seamless connectivity algorithm in ubiquitous networks

The b-phase of polyvinylidene fluoride (PVDF) is well known for its piezoelectric properties. PVDF films have been developed using solvent cast method. The films thus produced are in a-phase. The a-phase is transformed to piezoelectric b-phase when the film is hotstretched with various different stretching factors at various different temperatures. The films are then characterized in terms of their mechanical properties and surface morphological changes during the transformation from a- to b-phases by using X-ray diffraction, differential scanning calorimeter, Raman spectra, Infrared spectra, tensile testing, and scanning electron microscopy. The films showed increased crystallinity with stretching at temperature up to 808C. The optimum conditions to achieve b-phase have been discussed in detail. The fabricated PVDF sensors have been tested for free vibration and impact on plate structure, and its response is compared with conventional piezoelectric wafer type sensor. The resonant and antiresonant peaks in the frequency response of PVDF sensor match well with that of lead zirconate titanate wafer sensors. Effective piezoelectric properties and the variations in the frequency response spectra due to free vibration and impact loading conditions are reported. POLYM. ENG. SCI., 00:000–000, 2012. ª2012 Society of Plastics Engineers

Fabrication and characterization of micro-arc oxidized fluoride containing titania films on Cp Ti

The present study is focussed at establishing an appropriate electrolyte system for developing electrochemically stable and fluorine (F) containing titania (F-TiO2) films on Cp Ti by micro-arc oxidation (MAO) technique. To fabricate the F-TiO2 films on Cp Ti, different electrolyte solutions of chosen concentrations of tri-sodium orthophosphate (TSOP, Na3PO4 center dot I2H2O), potassium hydroxide (KOH) and various F-containing compounds such as ammonium fluoride (NH4F), potassium fluoride (KF), sodium fluoride (NaF) and potassium fluorotitanate (K2TiF6) are employed. The structural and morphological characteristics, thickness and elemental composition of the developed films have been assessed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) techniques. The in-vitro electrochemical corrosion behavior of the films was studied under Kokubo simulated body fluid (SBF) environment by potentiodynamic polarization, long term potential measurement and electrochemical impedance spectroscopy (EIS) methods. The XRD and SEM-EDS results show that the rutile content in the films vary in the range of 15-37 wt% and the F and P contents in the films is found to be in the range of 2-3 at% and 2.9-4.7 at% respectively, suggesting that the anatase to rutile phase transformation and the incorporation of F and P into the films are significantly controlled by the respective electrolyte solution. The SEM elemental mapping results show that the electrolyte borne F and P elements are incorporated and distributed uniformly in all the films. Among all the films under study, the film developed with 5 g TSOP+2 g KOH+3 g K2TiF6 electrolyte system exhibits considerably improved in-vitro corrosion resistance and therefore best suited for biomedical applications. (C) 2012 Elsevier Ltd and Techna Group S.r.l. All rights reserved.