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Bio-inspired catalyst compositions for enhanced oxygen reduction using nanostructured Pt electrocatalysts in polymer electrolyte fuel cells
No full textComposites of Nafion with a class of bio-molecules viz., plant hormones, are explored as potential polymer electrolytes for improving the proton transport inside the catalyst layer of a H2/O2 fuel cell. Specifically, four nitrogenous plant hormones, two each from the class of auxins and cytokinins have been investigated, following preliminary characterization of the composite dispersions and membranes. Interestingly, the use of indole-3-acetic acid (an auxin) in the catalyst layer reveals a 30% enhancement in Pt catalyst utilization and improved fuel cell performance by 150 mW /cm2. The effect of these
bio-molecules on the kinetic and mass transport parameters has been analyzed systematically using a combination of electrochemical and spectroscopic techniques
Artificially Designed Membranes Using Phosphonated Multiwall Carbon Nanotube-Polybenzimidazole Composites for Polymer Electrolyte Fuel Cells
No full textThe ability of phosphonated carbon nanotubes to offer an unprecedented approach to tune both proton conductivity and mechanical stability of hybrid polymer electrolytes based on the polybenzimidazole membrane is demonstrated
for fuel cell applications. The covalent attachment between the amino group of the 2-aminoethylphosphonic acid precursor and CNTs has been confirmed by NMR and IR experiments, while EDAX analysis indicates that one out of
every 20 carbon atoms in the CNT is functionalized. Proton conductivity of the composite membrane shows a remarkable 50% improvement in performance, while a maximum power density of 780 and 600mWcm-2 is obtained for the composite and pristine membranes, respectively. Finally, the ultimate strength determined for the composite and pristine membranes is 100 and 65 MPa, respectively, demonstrating the superiority of the composite. This study opens up a newstrategy to systematically tune the properties of polymer electrolytes for special applications by using appropriately functionalized CNTs
Influence of plane wave cut-off on structural and electronic properties in Sn-BEA and Ti-BEA zeolite water molecule interaction
No full textPeriodic systems are best described by the pseudo-potential methods. However, the accuracy of its
description depends on the cut-off of plane wave basis. This is much more critical in the case of weak
interactions, where a clear understanding on the influence of plane wave cut-off on the structural and
electronic properties is not readily available in the literature. In the present work, we have taken a metal
substituted beta zeolite–H2O complex for understanding this objective. Our studies show that while a
lower cut-off of 500 eV is sufficient for the convergence of the structural parameters, description of
energy-dependent properties necessitates a high cut-off value
Voltammetric behavior of perfluorocarboxylic acids and their corresponding ethyl esters on glassy carbon electrode: surface effects
No full textVoltammetric responses of trifluoroacetic acid,
perfluorobutyric acid, perfluorohexanoic acid, and perfluorooctanoic
acid (PFOA) were studied in acetonitrile/tetra-nbutylammonium
perchlorate medium on glassy carbon
electrode. All the four acids gave two voltammetric waves.
PFOA exhibits blocking effects. In the presence of excess
water, the first cathodic peak current increases, and the
second peak disappeared. Very small quantity of triethylamine
(TEA; 1–2 mM) was found to be effective in
suppressing the first cathodic peak. Both the peak current
and peak potential values were sensitive to water and TEA
content. The ester derivatives of all the four perfluorocarboxylic
acids (PFCAs), however, gave well-defined
cathodic reduction peak around −2.3 V. This peak appears
to be the best choice for quantitative estimation of PFCAs
Preparation and Characterization of Ceria-Based Electrolytes for Intermediate Temperature Solid Oxide Fuel Cells (IT-SOFC)
No full textSolid-oxide fuel cells (SOFCs) can be used for clean, efficient and environment-friendly energy conversion with a variety of
fuels at high temperature (1273 K). The high temperature operation accelerates unwanted reactions and creates materials
challenges; so, intermediate-temperature SOFCs (IT-SOFCs) have been developed. Reduction of the operating temperature
(between 873-1073 K) requires solid electrolyte materials with higher conductivities. In this study, partially substituted ceria as
solid electrolyte is experimented systematically for use in solid oxide fuel cells operating below 1073 K (intermediate temperature
range). Nine compositions namely, CeO2, Ce0.95Gd0.05O2-δ (CGO9505), Ce0.90Gd0.10O2-δ (CGO9010), Ce0.85Gd0.15O2-δ (CGO8515),
Ce0.80Gd0.20O2-δ (CGO8020), Ce0.95Sm0.05O2-δ (SDC9505), Ce0.90Sm0.10O2-δ (SDC9010), Ce0.85Sm0.15O2-δ (SDC8515) and
Ce0.80Sm0.20O2-δ (SDC8020) were synthesized by Glycine Nitrate (GN) combustion technique and investigated. The physical
properties and the other relevant features of the data obtained are analyzed with a view to use these alternate electrolyte materials
in IT-SOFC
3. Development of electrochemical process for the production of Tetra Ethyl Ammonium Hydroxide (TEAH) from Tetra Ethyl Ammonium Bromide (TEAB)
No full textStudies on development of electroless Ni–B bath for corrosion resistance and wear resistance applications
No full textElectroless deposition process has undergone numerous changes to meet the challenging needs
for a variety of industrial applications ever since the invention of the process during 1947. Among
the various metals that can be electrolessly plated, electroless nickel has proved its supremacy
for producing coatings with high corrosion resistance, hardness, wear resistance and uniformity.
Electroless nickel can be deposited from a variety of baths and the coating properties depends
upon the type of reducing agents and other deposition conditions. Electroless nickel–boron
coatings have received considerable interest nowadays because of the superior hardness,
corrosion and wear resistance characteristics. In this paper, the authors have reported on the
development of a biodegradable electroless Ni–B bath and evaluated its characteristic
properties. The influence of bath constituents, temperature and pH on the rate of deposition
was studied. Scanning electron microscopy, X-ray diffraction, X-ray fluorescence spectroscopy
and atomic absorption spectroscopy techniques were employed to find out the deposit
morphology and boron content in the deposits. The hardness and wear resistance of the
deposits were evaluated in the as deposited and heat treated conditions. The influence of sodium
hypophosphite as reducing agent on the Ni–B deposit has also been studied. The use of nickel
methane sulphonate as the metal ion source increases the bath lifetime without adversely
affecting the deposit qualities. Annealing the Ni–B deposit at 400uC for one hour resulted in an
increase in the hardness and thereby the wear resistance. The corrosion resistance of as plated
electroless Ni–B deposit is higher than the heat treated deposits. Also, the corrosion resistance is
highly enhanced by the incorporation of phosphorous to the nickel–boron alloy coating
Synthesis of Rh–carbon nanotube based heterostructures and their enhanced field emission characteristics
No full textSelective decoration of Rh nanospheres on acid functionalized carbon nanotubes has been demonstrated using Al as a sacrificial substrate. Remarkable field emission has been observed for this heterostructure as a high current density of 170 muA / cm2 is generated at an ultra-low threshold of 300 V/ mu m, compared to much smaller values for Rh nanospheres and carbon nanotubes separately
Removal of NO3– from Drinking Water by Electrocoagulation – An Alternate Approach
No full textThe present study provides an electrocoagulation method, for the removal of NO3
–
from drinking water using magnesium as the anode and cathode. The experiments
are carried out as a function of pH, temperature, and current density. The results
show that the maximum removal efficiency of 95.8% was achieved at a current density
of 0.25 A/dm2, at a pH of 7.0. The adsorption of NO3
– preferably fitting the Langmuir
adsorption isotherm suggests monolayer coverage of the adsorbed molecules.
The adsorption process follows a second-order kinetics model. Thermodynamic studies
show that the adsorption was exothermic and spontaneous in nature
Molecularly Imprinted Electrochemical Sensors
No full textIn this review, the applications of molecularly imprinted polymer (MIP) materials in the area of electrochemical
sensors have been explored. The designs of the MIPs containing different polymers, their preparation and their
immobilization on the transducer surface have been discussed. Further, the employment of various transducers
containing the MIPs based on different electrochemical techniques for determining analytes has been assessed. In
addition, the general protocols for getting the electrochemical signal based on the binding ability of analyte with the
MIPs have been given. The review ends with describing scope and limitations of the above electrochemical based MIP
sensors