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Selective deposition of zinc hexacyanoferrate on the metal impurity sites of a SWCNT/glassy carbon electrode
No full textIn this work, we report for the first time that multi-metal impurities present in SWCNTs aid ZnHCFmodification of the electrode and the charge–discharge characteristics of the composite. The multi-metal impurities in the as-supplied SWCNTs serve as nucleating centres or provide active sites for electrocrystallization of ZnHCF. ZnHCF-SWCNT/GCE was characterized using cyclic voltammetry, X-ray photoelectron
spectroscopy and transmission electron microscopy. Interestingly, the deposition of ZnHCF is restricted
only to the metal impurity surface sites and not to the surface of the walls of SWCNT, confirming again that the
deposition does not take place on the carbon surface of the nanotube. Intimate contact established between the metal impurities and ZnHCF is inferred to be responsible for the reduced charge-transfer resistance observed in the ac impedance measurements performed on the composite electrode. The calculated specific capacitance values of ZnHCF-SWCNT/GCE are 5 times higher than those obtained for SWCNT/GC
Glutamic acid-assisted sol–gel synthesis of multi-doped spinel lithium manganate as cathode materials for lithium rechargeable batteries
No full textLiMn2O4 and LiMgxSnyAlzMn2−x−y−zO4 (x, y, z = Mg, Sn, Al) (x = 0.01–0.09; y = 0.04–0.1; z = 0.35–0.20) powders have been synthesized via the sol–gel method for the first time using glutamic acid as the chelating agent. The synthesized samples have been subjected to physical and electrochemical
characterization. SEM images of parent LiMn2O4 show that the majority of the grains are 1 micrometer in size. The LiMg0.01Sn0.04Al0.35Mn1.6O4 and LiMg0.04Sn0.06Al0.30Mn1.6O4 particles present a low degree of agglomeration and the primary particles are 1 micrometer in size. TEM images of the spinel LiMn2O4 and LiMgxSnyAlzMn2−x−y−zO4 ascertain that the synthesized particles are nano-sized with uniform surface morphology. The LiMn2O4 samples calcined at 850 ◦C deliver a discharge capacity of 122 mAh g−1 in the first cycle. Among the compositions investigated, LiMg0.01Sn0.06Al0.30Mn1.6O4 delivers 115 mAh g−1 in the first cycle and exhibits stable cycling performance with a low capacity fade of 1 mAh g−1 cycle−1 over the 10 cycles investigate
Charge growth, dispersion in europium manganite (EuMnO3−ı) ceramics revealed using opto-impedance probe
No full textIn this preliminary report, we present the impedance characteristics of poly-crystalline europium manganite,
a promising colossal magneto resistance (CMR) system investigated under optical (∼5 eV) and magnetic (0.1 T) perturbations yielding some clues on the charge build-up and dispersion processes. This may possibly be resulting from switching between ferromagnetic and anti-ferromagnetic phases through a charge transfer transition mediated process centeringMn3+/4+ 3d spins thereby meriting a more detailed
study correlating with magnetic measurement
Electrochemical behaviour of tetra-n-butylammonium nonaflate as an ionic liquid and as a supporting electrolyte in aprotic solvents: a comparative study
No full textTetra-n-butylammonium nonaflate was synthesized, characterized and employed as a neat ionic liquid
and as supporting electrolyte in acetonitrile, N,N0-dimethylformamide, propylene carbonate and sulfolane
media. The electrochemical oxidation of ferrocene and hydroquinone as well as the electrochemical reduction of anthracene were investigated in all the media. Good correlation is established between the charge transfer rate, diffusion coefficient of all the three redox species and the viscosity of the five electrolyte media employed. The viscosity dependent solvation dynamics of the redox molecules thus appear to influence the charge transfer and mass transport behaviour in quite similar fashion over a wide viscosity range. The chemical stability and stability of electrogenerated free radicals however depend on
the nature of the solvent rather than the viscosit
A biocompatible nano TiO2/nafion composite modified glassy carbon electrode for the detection of fenitrothion
No full textA biocompatible nano TiO2/nafion composite modified glassy carbon electrode was developed for the detection of fenitrothion. This composite electrode was characterized by SEM, XRD, UV–visible, FTIR, TGA and cyclic voltammetry. Electrochemical techniques such as cyclic voltammetry, differential pulse voltammetry and amperometry were used for the detection of fenitrothion. Such modified electrode
produced high sensing current which is one of the promising characteristics of the electroanalytical sensor. The linear relationship between sensing current and concentration is obtained in differential pulse voltammetry technique for the fenitrothion concentration ranging from 0.2 to 4 lM with LOD
and LOQ of 0.0866 and 0.2889 lM respectively. The peak currents were reproducible with the relative
standard deviation of 5.1% (n = 6). The peak current obtained from the cyclic voltammetry is stable even
after 50 cycles. The recovery rate for the spiked water sample was calculated and compared with the data
obtained by HPLC analysi
Development of porous silicon matrix and characteristics of porous silicon/tin oxide structures
No full textPorous silicon (PSi) was formed at different current densities in the range of 5–60 mA/cm2 by electrochemical
anodized etching in HF for different durations in the range of 10–30 min. Above this PSi structure, SnO2 films were deposited by the spin coating technique. The PSi has been characterized by X-ray diffraction studies. Peaks pertaining to PSi along with those corresponding to SnO2 are observed. Atomic force microscopic studies indicate that very fine needle like silicon nanostructures are observed which is the result of the best PSi structure formed at 30 mA/cm2. For the SnO2 covered PSi structures, larger grains are observed with uniform coverage. The PSi samples prepared at current densities above and below 30 mA/cm2 show PL spectra with asymmetric and overlapped peaks. The PL profile of thin SnO2 film coated on PSi shows a peak at 633 nm and a small hump at about 660 n
Novel Li4Ti5O12/Sn nano-composites as anode material for lithium ion batteries
No full textLi4Ti5O12/Sn nano-composites have been prepared as anode material for lithium ion batteries by highenergy mechanical millingmethod. Structure of the samples has been characterized by X-ray diffraction (XRD), which reveals the formation of phase-pure materials. Scanning electron microscope (SEM) and transmission electron microscope (TEM) suggests that the primary particles are around 100 nm size. The local environment of the metal cations is confirmed by Fourier transform infrared (FT-IR) and the X-ray
photoelectron spectroscopy (XPS) confirms that titanium is present in Ti4+ state. The electrochemical properties have been evaluated by galvanostatic charge/discharge studies. Li4Ti5O12/Sn–10% composite delivers stable and enhanced discharge capacity of 200 mAh g�1 indicates that the electrochemical performance of Li4Ti5O12/Sn nano-composites is associated with the size and distribution of the Sn
particles in the Li4Ti5O12 matrix. The smaller the size and more homogeneous dispersion of Sn particles in the Li4Ti5O12 matrix exhibits better cycling performance of Li4Ti5O12/Sn composites as compared to bare Li4Ti5O12 and Sn particles. Further, Li4Ti5O12 provides a facile microstructure to fairly accommodate the volume expansion during the alloying and dealloying of Sn with lithiu
A comparative study of titanium nitride (TiN), titanium oxy nitride (TiON) and titanium aluminum nitride (TiAlN), as surface coatings for bio implants
No full textIn the present study, the performance of three titanium nitride coatings: TiN, TiON, and TiAlN for biomedical
applications were assessed in terms of their surface properties electrochemical corrosion in simulated body
fluid and cytotoxicity. Layers of TiN, TiON and TiAlN were deposited onto CP–Ti substrates by DC reactive magnetron sputtering method using a combination of a Ti, Ti–Al targets and an Ar–N2 mixture discharge gas. The presence of different phases was identified by XRD analysis. The morphology was determined through atomic force microscopy (AFM) imaging. The XPS survey spectra on the etched surfaces of TiN film exhibited the characteristic Ti2p, N1s, O1s peaks at the corresponding binding energies 454.5, 397.0, and 530.6 eV respectively. The characteristic Raman peaks were observed from the Laser Raman spectrometer. Platelet adhesion experiments were done to examine the interaction between blood and the materials in vitro. On
Control samples (CP Ti), platelets were seen as aggregates, whereas on coated samples, platelets were seen as singles, without any significant spreading. Cytocompatibility studies of coated samples were carried out with
bare titanium (CP Ti — ASTM B 348) as controls. L-929 mouse fibroblast cells were used for samples. All materials showed good cytocompatbility with cell lines use
Enhanced oxygen reduction reaction activity through spillover effect by Pt–Y(OH)3/C catalyst in direct methanol fuel cells
No full textDynamic spillover of metal oxide aided by yttrium hydroxide through its altervalent nature is utilized to develop
a new carbon supported Pt–Y(OH)3 hybrid catalyst with varying Pt:Y atomic ratio of 1:1, 2:1 and 3:1 and characterized by X-Ray diffraction and Transmission electron microscopy techniques. Pt–Y/C catalysts
exhibit significant improvement in oxygen reduction reaction (ORR) over commercial Pt/C. The effects of
composition toward ORR with and without methanol have been studied. Among the various Pt–Y(OH)3/C catalysts, the one with Pt to Y in 3:1 atomic ratio shows the highest activity for ORR in aqueous HClO4 solution without methanol while the one with Pt to Y in 2:1 atomic ratio shows the maximum activity for ORR in presence of methanol. A direct methanol fuel cell (DMFC) employing carbon-supported Pt–Y(OH)3 as the
cathode catalyst delivers a peak-power density of 105 mW/cm2 at 70 °C as compared to a peak-power density
of 64 mW/cm2 obtained with the DMFC employing carbon-supported Pt catalyst operating under similar condition
