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Effects of primary dicarboxylic acids on microstructure and mechanical properties of sub-microcrystalline Ni–Co alloys
No full textNickel–cobalt alloys were deposited from sulfate electrolyte with oxalic, malonic and succinic acids as additives and their microstructure and mechanical properties were studied. The crystal structure, surface morphologies, and chemical composition of coatings were investigated using X-ray diffraction, scanning electron microscope, and energy dispersive spectroscopy. The crystal structure and surface morphology analysis showed that the addition of dicarboxylic acid leads to (2 0 0) crystal face and the surface were
more compact and uniform due to the grain refining. Ni60–Co40 alloy was achieved when succinic acid is used as additiv
Enzymeless creatinine estimation using poly(3,4-ethylenedioxythiophene)-beta-cyclodextrin
No full textA novel enzymeless biosensor has been constructed for the quantitative estimation of creatinine using bcyclodextrin
(bCD) incorporated poly-3,4-ethylenedioxythiophene (PEDOT) modified glassy carbon electrode (GCE). The PEDOT film with and without bCD was deposited on a GCE by electropolymerization of EDOT from an aqueous solution containing lithium perchlorate and bCD. Polymer films were characterized by UV–visible spectroscopy, cyclic voltammetry and scanning electron microscopy (SEM). The selective
interactions of the bCD-incorporated PEDOT film with creatinine in neutral Tris buffer solutions were
elucidated using electrochemical impedance analysis. Complex formation between bCD and creatinine was inferred from regular shifts in the electrode potential versus creatinine concentration. In the potentiometric evaluation, the biosensor electrode exhibited a fast response time (60 s), linear shift in the potential over a concentration range of 10^4 10^1 M with a lower detection limit of 5*10^5 M and good stability, retaining nearly 95% of the initial response after 1 month of shelf life. The results of the studies
on the interferences from glucose, ascorbic acid, uric acid, urea and ammonium ions are also presente
Relative deactivation of boron-doped diamond (BDD) and glassy carbon (GC) electrodes in different electrolyte media containing substituted phenols – Voltammetric and surface morphologic studies
No full textThe relative deactivation of boron-doped diamond (BDD) and glassy carbon (GC) electrodes during the anodic oxidation of three different substituted phenols namely 2,6-dichlorophenol (DCP), 2,6-dimethylphenol (DMP) and 2,6-dimethoxyphenol (DMeoP) in aqueous acidic, acidic methanol and neutral/acidic microemulsion media were investigated using cyclic voltammetry (CV). Voltammetric analysis reveals
that the anodic potential limit for the BDD electrode is higher than the GC almost in all the media. The
electrooxidation of phenolic compounds takes place at high overpotential on the BDD when compared to the GC in all the media. Multisweep voltammetric experiments suggest that in the acidic methanol medium, no electrode fouling is observed for the anodic oxidation of the phenols and in the other three media containing DCP and DMP, the relative deactivation of the electrodes increases as follows: acidic
microemulsion < aqueous acidic < neutral microemulsion (on the BDD) and neutral microemulsion < acidic microemulsion < aqueous acidic (on the GC). Passivation of the BDD and GC electrodes in supporting electrolytes containing the DMP were also investigated by Scanning Electron Microscopy
(SEM). In all the media and on both the electrodes, the DCP shows high oxidation potential and low anodic current followed by the DMP and DMeo
Microwave synthesis of novel high voltage (4.6 V) high capacity LiCuxCo1−xO2±ı cathode material for lithium rechargeable cells
No full textLayered LiCuxCo1−xO2±ı (0.0≤x≤0.3) has been synthesized using microwave method. This method possesses many advantages such as homogeneity of final product and shorter reaction time compared to other conventional methods. The structure and electrochemical properties of the synthesized
materials are characterized through various methods such as XRD, SEM, FTIR, XPS and galvanostatic charge/discharge studies. The XRD patterns of LiCuxCo1−xO2±ı confirm the formation of single-phase layered material. SEM images show that the particles are agglomerated and the average particle size decreases with increasing amount of copper. Electrochemical cycling studies are carried out between 2.7
and 4.6V using 1M LiPF6 in 1:1 EC/DEC as electrolyte. The charge/discharge cycling studies of layered material with LiCu0.2Co0.8O19 exhibit an average discharge capacity of∼150mAhg−1 over the investigated 50 cycle
CTAB-assisted sol–gel synthesis of Li4Ti5O12 and its performance as anode material for Li-ion batteries
No full textA simple CTAB-assisted sol–gel technique for synthesizing nano-sized Li4Ti5O12 with promising electrochemical performance as anode material for lithium ion battery is reported. The structural and morphological properties are investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The electrochemical performance of both samples (with and without CTAB) calcined at 800 8C is evaluated using SwagelokTM cells by galvanostatic charge/discharge cycling at roomtemperature. The XRD pattern for sample prepared in presence of CTAB and calcined at 800 8C shows high-purity cubicspinel Li4Ti5O12 phase (JCPDS # 26-1198). Nanosized-Li4Ti5O12 calcined at 800 8C in presence of CTAB exhibits promising cycling performance with initial discharge capacity of 174 mAh g-1 (100% of theoretical capacity) and sustains a capacity value of 164 mAh g-1 beyond 30 cycles. By contrast, the sample prepared in absence of CTAB under identical reaction conditions exhibits initial discharge capacity of 140 mAh g-1 (80% of theoretical capacity) that fades to 110 mAh g-1 after 30 cycle
Characteristics of GZO thinfilms deposited by sol–gel dip coating
No full textZinc oxide(ZnO)films were deposited by sol–gel dip coating using the acrylamide route. The films were doped with different concentrations of gallium in the range 250–1200 ppm. The films exhibited hexagonal structure. The grain size decreased from 100 to 10 nm as the dopant concentration increased. The resistivity of the doped samples decreased from 10 power 3 to 3*10 power 3 Ohm cm. The bandgap value shifted towards the short-wavelength region as the dopant concentration increased. XPS studies indicated doping of Ga in Zn
Application of Functionalized CNT–Polymer Composite Electrolytes for Enhanced Charge Storage in “All Solid-State Supercapacitors”
No full textThe ability of specifically functionalized carbon nanotubes to enhance proton transport in Nafion and polybenzimidazole membranes leading to improvement in the specific capacitance of an all solid-state supercapacitor is demonstrated. Cyclic voltammetry experiments reveal a 25% improvement (185 and 150 F per gram of RuO2 for composite and Nafion membranes respectively) in capacitance by a meager 0.05 wt% addition of sulfonated MWCNTs in Nafion membranes. On the other hand, an addition of 1% phosphonated MWCNTs results in ∼60% improvement in olybenzimidazole (PBI) based composites (from 160 to 260 F g−1). Further, composite membranes based on functionalized MWCNTs show increased cycle life which is attributed to the presence of electrostatically linked network structures due to functional moieties on the side walls of carbon
nanotubes that increases the interfacial charge density and integrity of the membrane. The equivalent series resistance for the PBI and PBI phosphonated MWCNT (PBpNT) membranes is 470 and 89 milli ohm respectively suggesting improved proton conductivity with the composite membrane. Charge
discharge measurements reveal a capacitance value of 500 F g−1 for PBpNT membrane based supercapacitors even after 1000 cycles of operation. Use of such nanocomposite membranes is expected to dramatically improve the life time as well as performance of supercapacitors which in
turn would facilitate deployment in different applications such as hybrid electric vehicles
An electrochemical method for the removal of arsenate from drinking water
No full textThe present invention provides an electrochemical method for the removal of arsenate from drinking water, wherein the arsenate is removed by adsorption of metal hydroxide, formed by 'in-situ' anodic oxidation. The electrochemical method, of the present invention, for the removal of arsenate from drinking water, obviates the drawbacks of the commonly used physico-chemical treatments processes such as lime softening, sorption techniques and membrane techniques. The electrochemical method consists of an electrochemical cell fitted with an anode of mild steel or aluminium plate and stainless steel cathode with an inter-electrode distance of 0.5 to 1.5cm. Drinking water containing 0.5 to 3.0 mg/l of arsenate at a pH in the range of 3-10 and at a temperature between 20-60°C is electrolysed at anode and cathode current densities between 0.05 - 0.2A.dm"2. The iron hydroxide / aluminium hydroxide formed from the anode during electrolysis adsorbs the arsenate present in the water and settles at the bottom. The removal efficiency of this method is up to 98%
Improved performance of phosphonated carbon nanotube–polybenzimidazole composite membranes in proton exchange membrane fuel cells
No full textDevelopment of thermally stable polymer electrolyte membranes with higher proton conductivity as well as mechanical stability is a key challenge in commercializing PEM fuel cells operating above 100 degree Centigrade. Polybenzimidazole membranes are one of the promising candidates in this category although with limited mechanical stability and moderate proton conductivity. Here the incorporation of functionalized MWCNT is shown to increase both these key parameters of the polybenzimidazole
membranes. Further, formation of a domain like structure after the incorporation of phosphonated MWCNTs (P-MWCNTs) in phosphoric acid doped polybenzimidazole membranes is demonstrated. The enhanced performance has been attributed to the formation of proton conducting networks that
formed along the sidewalls of P-MWCNTs with a domain size of 17 nm as estimated from the small angle X-ray scattering measurements. Membrane electrode assembly (MEA) impedance measurements further reveal that the activation energy of oxygen reduction reaction (ORR) reduced for the composite
membranes with enhanced proton conductivity. In addition, the mechanical strength measurements reveal a significant improvement in the yield strength and ultimate strength. Also, the mechanical strength of the composite membrane has been increased significantly as indicated by the improvement
in the ultimate strength from 65 MPa to 100 MPa for the pristine and composite membranes, respectively. The optimum loading of P-MWCNTs is found to be 1% as inferred from the polarization measurements carried out using pure hydrogen and oxygen. Thus, this study provides a unique opportunity to tune the properties of polymer electrolytes to prepare application oriented hybrid membranes using CNTs with tailor-made functional groups
Electrochemical behaviour of metal hexacyanoferrate converted to metal hydroxide films immobilized on indium tin oxide electrodes—Catalytic ability towards alcohol oxidation in alkaline medium
No full textIn this work, we demonstrate a simple method to modify indium tin oxide (ITO) electrodes in order to perform electro-catalytic oxidation of alcohols in alkaline medium. Metal hexacyanoferrate (MHCF) films such as nickel hexacyanoferrate (NiHCF) and copper hexacyanoferrate (CuHCF) were successfully immobilized on ITO electrodes using an electrochemical method. Scanning electron microscopy (SEM)
and X-ray photoelectron spectroscopy (XPS) were employed to characterize the structural and morphological aspects of MHCF films. Cyclic voltammetry (CV) was used to study the redox properties and to determine the surface coverage of these films on ITO electrodes. Electrochemical potential cycling was carried out in alkaline medium in order to alter the chemical structure of these films and convert to
their corresponding metal hydroxide films. SEM and XPS were performed to analyze the structure and morphology of metal hydroxide modified electrodes. Electro-catalytic oxidation ability of these films towards methanol and ethanol in alkaline medium was investigated using CV. From these studies we found that metal hydroxide modified electrodes show a better catalytic performance and good stability
for methanol oxidation along with the alleviation of CO poisoning effect. We have obtained an anodic oxidation current density of ∼82mAcm−2 for methanol oxidation, which is at least 10 fold higher than that of any metal hydroxide modified electrodes reported till date. The onset potential for methanol oxidation is lowered by ∼200mV compared to other chemically modified electrodes reported. A plausible
mechanism was proposed for the alcohol oxidation based on the redox properties of these modified electrodes. The methodology adapted in this work does not contain costlier noble metals like platinum and ruthenium and is economically viabl