IR@CECRI
Not a member yet
2644 research outputs found
Sort by
Electro-Oxidation of Borohydride on Rhodium, Iridium, and Rhodium–Iridium Bimetallic Nanoparticles with Implications to Direct Borohydride Fuel Cells
No full textElectrochemical oxidation of borohydride is studied on nanosized rhodium, iridium, and bimetallic rhodium–iridium catalysts
supported onto Vulcan XC72R carbon. The catalysts are characterized by X-ray diffraction, transmission electron microscopy, and
X-ray photoelectron spectroscopy in conjunction with cyclic voltammetry and polarization studies. The studies reveal that a 20 wt
% bimetallic Rh–Ir catalyst supported onto carbon �Rh–Ir/C� is quite effective for the oxidation of borohydride. Direct borohydride
fuel cell with Rh–Ir/C as the anode catalyst and Pt/C as the cathode catalyst exhibits a peak power density of 270 mW/cm2
at a load current density of 290 mA/cm2 as against 200 mW/cm2 at 225 mA/cm2 for Rh/C and 140 mW/cm2 at 165 mA/cm2
for Ir/C while operating at 80°C. The synergistic catalytic activity for the bimetallic Rh–Ir nanoparticles toward borohydride
oxidation is corroborated by density-functional theory calculations using electron-localization function
One-pot, glycine-assisted combustion synthesis and characterization of nanoporous LiFePO4/C composite cathodes for lithium-ion batteries
No full textNanoporous LiFePO4/C composite cathodes have been synthesized by a novel one-pot, glycine-assisted
combustion (GAC) method in presence of 2 wt.% Super P carbon in both Ar and 90% Ar–10% H2 atmospheres
at 750 ◦C for a short time of 6 h. While the Ar atmosphere offers phase pure samples, the
Ar–H2 atmosphere leads to the formation of impurity phases as indicated by X-ray diffraction data. The
combustion-initiated expulsion of gases aids the formation of a nanoporous LiFePO4/C composite structure
as evident from electron microscopic analysis, which could allow easy penetration of the electrolyte
and realization of an electronic–ionic 3D network. The nanoporous LiFePO4/C sample synthesized in Ar
atmosphere exhibits a high discharge capacity of 160mAhg−1 with 3% capacity fade in 50 cycles and
high rate capability. With a short reaction time, the GAC method offers an energy efficient approach to
synthesize high performance olivine LiFePO4/C composite cathodes
Surfactant effects on methanol oxidation at Pt–Ru/C coated glassy carbon electrode
No full textThe role of surfactants, cetyl trimethyl ammonium
bromide (CTAB), sodium dodecyl sulphate (SDS) and
Triton X-100 (in the catalyst), on methanol oxidation at
commercial 50:50 Pt–Ru/C catalyst-coated glassy carbon
has been studied using cyclic voltammetry, scanning
electron microscopy (SEM) and Fourier transform infrared
spectroscopy (FT-IR). Surfactant containing catalysts
showed a considerable reduction in the methanol oxidation
potential. In terms of oxidation potential, better results
(lower methanol oxidation potential) were observed in the
order SDS>Triton X-100>CTAB>no surfactant. SEM
studies on the catalyst ink showed better homogeneity in
the sample prepared using surfactant. This indicates better
Pt Pt contact, which is likely to favour methanol adsorption
and its oxidation. Hence, lowering of oxidation potentials
for methanol oxidation could be seen with use of
surfactants. Results of FT-IR on the catalyst ink showed
definite changes in the frequencies in the case of Pt–Ru/C
containing surfactants indicating definite interaction between
catalyst and surfactant. Catalysts, with and without
surfactants, yielded linear plots of concentration vs peak
currents for methanol oxidation (0–2 M). With surfactant
containing catalysts, reduction in methanol oxidation
current was observed, and the order followed was the
reverse of the above
A process for the preparation of highly pure manganse sulphate electrolyte useful for electrodeposition of highly pure electrolytic manganese dioxide(HPEMD")
No full textThe invention relates to a process for the preparation of highly pure manganese sulphate electrolyte useful for electrodeposition of highly pure electrolytic manganese dioxide (HPEMD). In the process of the present invention the manganese sulphate solution containing monovalent cations, in particular K and Na are removed as a complex, viz. jarosite, which is highly crystalline and insoluble from manganese sulphate under optimum conditions. This has been done by digesting the manganese sulphate solution containing monovalent cations with ferric sulphate, at a pH of 1.5 to 3.0, for a duration of 15 to 180 minutes. The temperature being maintained between 80 to 100°C. Bringing about precipitation with suitable addition of seeding. Allowing to cool, followed by filtration. Subsequently treating either with CaO or calcine to raise the pH. The present invention thus provides a process for the preparation of highly pure manganese sulphate electrolyte by the removal of monovalent metal ions from manganese sulphate solution, which is a precursor for the electrodeposition of highly pure electrolytic manganese dioxide (HPEMD)
Electrochemical assay of the nitrate and nitrite reductase activities of Rhizobium japonicum
No full textThiswork describes an electrochemical method for the determination of the nitrate and nitrite reductase
activities of Rhizobium japonicum. The advantage of themethod lies in the use of whole cells for the analysis
and we earlier developed this protocol for the assay of NO. The results obtained are comparable to the
spectrophotometric Griess assay. As the method is based on electrochemical reduction, the commonly
interfering biological components like ascorbic acid, uric acid, dopamine, etc., will not interfere with the
analysis. This method can be extended to the fabrication of biosensors for nitrate and nitrite using the
same principle
Synthesis of LiMn2O4 from a gelled ovalbumin matrix
No full textA simple and inexpensive route for the preparation of LiMn2O4 using ovalbumin (egg white) as a gelating agent is described. Gelation of freshly
extracted ovalbumin was effected by changes in ionic strength brought about by the addition of nitrate precursors to an aqueous solution of
ovalbumin and subsequent warming. This resulted in tiny pockets of precursor materials getting trapped in the matrix of the gelled ovalbumin. Heat
treatment of the gelled mass yielded submicron-sized LiMn2O4 crystals at temperatures as low as 400 8C
A Self-Supported Direct Borohydride-Hydrogen Peroxide Fuel Cell System
No full textA self-supported direct borohydride-hydrogen peroxide fuel cell system with
internal manifolds and an auxiliary control unit is reported. The system, while operating
under ambient conditions, delivers a peak power of 40 W with about 2 W to run the
auxiliary control unit. A critical cause and effect analysis, on the data for single cells and
stack, suggests the optimum concentrations of fuel and oxidant to be 8 wt. % NaBH4 and 2
M H2O2, respectively in extending the operating time of the system. Such a fuel cell system
is ideally suited for submersible and aerospace applications where anaerobic conditions
prevail
Treatability of resin effluents by electrochemical oxidation using batch recirculation reactor
No full textElectro oxidation processes are developed throughout the world for ambient temperature destruction
of organic wastes. Several of these processes are based on mediated electrochemical oxidation. This article presents the
experimental results of electro chemical study based on mediated electrochemical oxidation process conducted for
synthetic organic ion exchange resin materials. Investigation was carried out using the traditional noble metal oxide
coated anode, ruthenium oxide-titanium and the mediator used for the experiment was ferrous sulphate, with sodium
chloride as supporting electrolyte. The concentration of sodium chloride was maintained at 5, 8, 12 gm/L. The experiment
was carried out in batch recirculation reactor with varied current densities for various flow rates. The study highlighted
that in batch reactor set up the best effect of total organic content reduction was found to occur at 3.75 A/dm2 with flow
rate of 20 L/h. The simulated studies were carried out for different volumes of effluent and current densities. A graphical
analysis was made between the experimental and simulated values and it was found that both the values are very clos
The influences of some additives on electrochemical behaviour of nickel electrodes
No full textNickel hydroxide is used as an active material in positive electrodes of rechargeable
alkaline batteries. Since the nickel hydroxide electrode exhibits a poor performance which
results not only from the competitive reactions of the oxidation of the active material but
also from the evolution of oxygen. Its reduced charge acceptance is suspected to be related
to a relatively long distance between nickel hydroxide particles and the nearest portion of
the substrate. The practical capacity of the positive nickel electrode depends on the efficiency
of the conductive network connecting the Ni(OH)2 particle with the current
collector.
In this study, a pasted-type electrode is prepared using spherical nickel hydroxide powder
as the main active material on a foamed nickel grid as a current collector. The effects of
additives such as metallic cobalt powder, cobalt hydroxide, calcium carbonate and cobalt
powder with calcium carbonate on the electrode performance are examined. The calcium
carbonate addition increases the oxygen evolution potential while the metallic cobalt
powder and its compounds enhance the conductivity of the active material.
This combined effect in nickel hydroxide electrode in turn increases the capacity of the Ni–
MH battery due to the augmentation in the utilization of the active material of the positive
electrode
Methanol tolerant oxygen-reduction activity of carbon supported platinum–bismuth bimetallic nanoparticles
No full textThe oxygen reduction activity and methanol
tolerance of Pt–Bi/C electrocatalysts were studied using
electrochemical voltammetric techniques including rotating
ring-disk electrode. The Pt–Bi/C catalyst was prepared via a
polyol method and subjected to heat treatment to increase the
degree of alloying. X-ray diffraction studies revealed the
unalloyed character of the as-prepared catalyst and alloy
formation upon heat treatment. The electrochemical behaviour
of both catalysts showed different behaviour in dilute
acid electrolytes, namely sulphuric and perchloric acids. In
both electrolytes, the oxygen reduction reaction was found to
occur via the four-electron process revealing that the
mechanism of oxygen reduction is unaltered even in the
presence of excess of methanol. Pt–Bi/C catalyst material
showed dramatically different properties and reactivity with
respect to oxygen reduction activity and methanol tolerance
in perchloric and sulphuric acids. The onset potential for
oxygen reduction reaction (ORR) significantly shifted by
about 100 mV to more negative values and at the same time
the current density was significantly enhanced. This type of
non-ideal methanol-tolerant behaviour among Pt bimetallics
and a ‘‘trade off’’ is common with all the known so-called
methanol tolerant combinations of Pt. In general, the Pt–Bi
surface appeared to have a negligibly lesser sensitivity
towards methanol activity compared to pure platinum