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Large enhanced dielectric permittivity in polyaniline passivated core-shell nano magnetic iron oxide by plasma polymerization
No full textCommercial samples of Magnetite with size ranging from 25–30nm were coated with polyaniline by
using radio frequency plasma polymerization to achieve a core shell structure of magnetic nanoparticle
(core)–Polyaniline (shell). High resolution transmission electron microscopy images confirm the core
shell architecture of polyaniline coated iron oxide. The dielectric properties of the material were
studied before and after plasma treatment. The polymer coated magnetite particles exhibited a large
dielectric permittivity with respect to uncoated samples. The dielectric behavior was modeled using a
Maxwell–Wagner capacitor model. A plausible mechanism for the enhancement of dielectric
permittivity is propose
Osmium Organosol on DNA: Application in Catalytic Hydrogenation Reaction and in SERS Studies
No full textOsmium (Os) organosol on DNA scaffold has been synthesized by utilizing a homogeneous reduction route. The
synthesis was done by the reduction of OsO4 with tetrabutylammonium borohydride (TBABH4) in the presence of DNA in
acetone within 10 min of stirring at room temperature. Different morphologies were synthesized by varying the DNA to OsO4
molar ratio and controlling the other reaction parameters. The eventual diameters of the individual Os particles in organosol
were ∼1−3 nm, and the nominal lengths of the wires were ∼1−2 μm. The potentiality of the Os organosol was tested in two
different applications: one is the catalytic hydrogenation of cyclohexene to cyclohexane and other is the surface enhanced Raman
scattering (SERS) studies. The SERS study has been examined using MB as a Raman probe, and the EF value is found to be the
highest in the case of Os organosol having aggregated wires (short size) compared to longer wires. The fast synthesis of Os
organosol on DNA and their potential catalytic and SERS activity will be found to be very useful in the near future for the
catalytic applications of various organic reactions and in the fields of sensors, electronic devices, and fuel cells
rGO/nano Sb composite: a high performance anode material for Na+ ion batteries and evidence for the formation of nanoribbons from the nano rGO sheet during galvanostatic cycling
No full textLithium ion batteries exhibit high energy and power densities, thereby making them a promising power
sources for multifarious applications. However, the abundance of lithium (Li) is one of the major critical
issues for using Li battery technologies. Therefore, for large-scale applications a sodium (Na) ion battery
is one of the apt alternatives for portable electronics instead of expensive Li ion batteries. One of the
challenging issues in Na+ ion batteries is the difficulty to understand the chemistry involved in view of
the large size of the Na+ ion as compared to the Li+ ion, which makes the alloying/dealloying difficult
during cycling. Hence, in this present work, we explore an innovative concept of storing Na+ ions in
reduced graphene oxide/antimony (Sb) metal composites. Such a concept of storing Na+ in the rGO/Sb
composite is one of the simplest ways to enhance the electrochemical performance of metal-based
anodes for sodium ion batteries. Furthermore, it is seen that the nano rGO sheet transforms to
nanoribbons upon galvanostatic cycling, as evidenced by TE
Comparative Electrocatalytic Performance of Single-Walled and Multiwalled Carbon Nanotubes for Zinc Bromine Redox Flow Batteries
No full textCarbon nanotubes (CNTs) have been employed
as electrode materials in rechargeable zinc bromine
redox flow batteries (ZBB) owing to their high electrocatalytic
activity, remarkable electrical conductivity, and excellent
mechanical strength with high Young’s modulus. The
electrocatalytic effect of single-walled carbon nanotube
(SWCNT) and multiwalled carbon nanotube (MWCNT)
electrodes for the 2Br−/Br2 redox couple has been investigated
for zinc bromine redox flow battery application. The anodic
peak current density of SWCNT electrode is found to be about 16 mA cm−2
, which is almost 50% higher than that of MWCNT,
indicating the enhanced electrocatalytic effect of SWCNT perhaps due to a large amount of basal planes. The peak separation
between the anodic and cathodic process at SWCNT and MWCNT electrodes is 201 and 126 mV, respectively, demonstrating
the quasireversible nature of the 2Br−/Br2 redox reaction. Moreover, the peak separation for the MWCNT electrode is 37% less
compared to that on the SWCNT electrode, revealing better reversibility. FTIR, Raman spectroscopy, scanning electron
microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) have been used to
further investigate the composition and morphological changes of CNT before and after cycling. Zinc bromine redox flow cell
made with CNT-anchored carbon felt (CF) as bromine electrode exhibits improved electrochemical performance in terms of
efficiency and durability. Particularly, SWCNT-modified electrode possesses 98% energy efficiency retention even after 200
cycles of charge−discharge process, offering great promise as high-performance electrodes for zinc bromine redox flow batter
DNA-Mediated Fast Synthesis of Shape-Selective ZnO Nanostructures and Their Potential Applications in Catalysis and Dye-Sensitized Solar Cells
No full textShape-selective ZnO nanoparticles (NPs) with various morphologies have been synthesized within 2 min of
microwave heating by the reaction of Zn(NO3)2·2H2O with NaOH in the presence of DNA. The size and shape of the materials
can be tuned by controlling the molar ratio of Zn(II) salt to DNA and by altering the other reaction parameters. The role of
DNA and other reaction parameters for the formation and growth mechanisms of different morphologies has been elaborated.
The potentiality of the DNA−ZnO NPs has been tested in the catalysis reaction for the decomposition of toxic KMnO4, and the
effect of different morphologies on the catalysis reaction has been examined. Moreover, the suitability of the materials is also
tested for dye-sensitized solar cell (DSSC) applications, and it was observed that all the morphologies of ZnO NPs can be used as
a potential anode material in DSSC application
An in situ generated carbon as integrated conductive additive for hierarchical negative plate of lead-acid battery
No full textIn this work, we report an in situ generated carbon from sugar as additive in the Negative Active Mass
(NAM) which enhances the chargeedischarge characteristics of the lead-acid cells. In situ formed sugar
derived carbon (SDC) with leady oxide (LO) provides a conductive network and excellent protection
against NAM irreversible lead sulfation. The effect of SDC and carbon black (CB) added negative plates are
characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM),
galvanostatic chargeedischarge, cyclic voltammetry (CV) and electrochemical impedance spectroscopy
(EIS), respectively. The results show that subtle changes in the addition of carbon to NAM led to subsequent
changes on the performance during partial-state-of-charge (PSoC) operations in lead-acid cells.
Furthermore, SDC added cells exhibit remarkable improvement in the rate capability, active material
utilization, cycle performance and charge acceptance compared to that of the conventional CB added
cells. The impact of SDC with LO at various synthesis conditions on the electrochemical performance of
the negative plate is studied systematically
Enhanced performance of dye-sensitized solar cells with TiO2blocking layers and Pt counter electrodes prepared by physical vapordeposition (PVD)
No full textTitanium dioxide (TiO2) thin films as block layers are prepared by DC reactive magnetron sputtering.X-ray diffraction (XRD) and TEM-(SAED) analyses of the films reveal that they are polycrystalline innature and have tetragonal structure with preferred orientation along the (101) direction. The surfacemorphological studies by FESEM and AFM reveal the uniform surface coverage of the grains on the surfaceof the films. An optical transmittance value of 80% in the visible light region with the optical band gapvalue of 3.2 eV is measured. This sputtered TiO2thin film is used as a blocking layer over which a thicklayer of TiO2of about 10 �m was prepared using TiO2paste and this stack is used as the photoanode of aDSSC cell. Electron beam evaporated platinum thin film on FTO coated glass substrate is used as counterelectrode. The performance of the cell with a Vocof 0.698 V, a Jscof 6.8 mAcm−2and an efficiency of 4.2%was achieve
Molecular Motions Aided Thermally Responsive Biocompatible Textile Pads
No full textDevelopment of smart and intelligent textiles (fabrics) is
sought after for tremendous applications ranging from textile
industries to robotic engineering. [1–5] Synergy of textile chemistry
and polymer engineering can leads to the development
of such smart and functional composite materials. Moreover,
such a synergy can also bring mechanical fl exibility, strength
and thermal stability to the designed fabrics. Thermally responsive
polymer (TRP) composites are one such class of materials
where the polymers can respond to external thermal stimuli
causing molecular level global or local dimensional changes.
Different types of TRPs in the forms of solution (liquid), fi bres,
foams, and fi lms were demonstrated in the recent past. [6–8]
Dimensional changes happening in these TRPs can be incorporated
to the fabrics for making smart woven and nonwoven
textiles
Manganese hexacyanoferrate derived Mn3O4 nanocubes–reduced graphene oxide nanocomposites and their charge storage characteristics in supercapacitors
No full textMn3O4–reduced graphene oxide (RGO) nanocomposites were prepared by chemical decomposition of the
manganese hexacyanoferrate (MnHCF) complex directly on the graphene surface. XRD studies revealed the
formation of crystalline hausmannite Mn3O4 nanocubes in the as-prepared nanocomposites without any heat
treatment. The FE-SEM images showed the formation of Mn3O4 nanocubes on the graphene surface in the
as-prepared nanocomposites. HR-TEM studies confirmed the homogeneous dispersion of B25 nm Mn3O4
nanocubes on graphene nanosheets. The amount of Mn3O4 nanocubes and graphene in the nanocomposites
was estimated using TGA analysis from room temperature to 800 1C in air. The FT-IR and Raman spectroscopic
analysis confirmed the functional groups in the nanocomposites and defects in graphene nanosheets
in the nanocomposites. Cyclic voltammetry and galvanostatic charge–discharge experiments demonstrated a
high specific capacitance of 131 F g-1 in 1 M Na2SO4 electrolyte at a current density of 0.5 A g-1 for the
RGM-0.5 nanocomposite. A capacitance retention of 99% was observed for 500 charge–discharge cycles at
a current density of 5 A g-1, which conformed the excellent stability of the RGM electrodes. The prepared
Mn3O4–RGO nanocomposites are promising for electrochemical energy storag
Enhanced catalytic and SERS activities of CTAB stabilized interconnected osmium nanoclusters
No full textA new route for the formation of osmium nanoparticles (NPs) having different morphologies like
aggregated clusters, chain-like networks, and small spheres are reported. The synthesis was done by
utilizing a simple wet-chemical method at room temperature (RT) by the reaction of OsO4, cetyl
trimethyl ammonium bromide (CTAB), 2,7-dihydroxynaphthalene (2,7-DHN) and NaOH under 30 min of
reaction. The diameter of the individual particles in all the morphologies was B1–3 nm. The synthesized
materials have been tested for catalysis and SERS studies. The catalysis study was examined taking different
organic nitro compounds and the catalysis rate was found superior as compared to other reports. The surface
enhanced Raman scattering (SERS) study was done taking Rose Bengal (R Be) as a probe molecule and the
observed enhancement factor (EF) value was found superior or comparable to most of other noble metal
NPs. The overall synthesis process was simple, less time consuming and cost-effective. The enhanced
catalytic and SERS activities of the Os NCs might open up a new avenue for the application in other organic
catalysis reactions, SERS based detection of environmentally important trace bio-molecules and sensor