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Wavelet based spectral approach for solving surface coverage model in an electrochemical arsenic sensor - An operational matrix approach
No full textSurface coverage parameter of an electrochemical sensor plays a vital role in enhancing the figure of
merits of the sensor. Developing a theoretical model for the surface coverage will help to standardize the
fabrication of working electrodes used in electrochemical sensors. In this background, a wavelet based
spectral algorithm has been developed to model the surface coverage of an arsenic sensor. For the model,
Michaelis-Menten constant of fluorine doped cadmium oxide (F-doped CdO) working electrode based
arsenic sensor was used as the seed fount. Theoretical analysis for the estimation of surface coverage
based on Michaelis-Menten constant with nonlinear reaction-diffusion equation is considered. In order
to estimate the Michaelis-Menten constant and maximum current response, the measured current
values are linearized with the help of Hanes-woolf plot. Using the Legendre wavelet spectral approach,
the nonlinear reaction-diffusion equation is converted into a system of algebraic equations through
operational matrix of derivatives. The surface coverage was determined using Legendre wavelets and this
method can be determined the desired surface coverage for detecting arsenic in water of specific rang
Boosting Pt oxygen reduction reaction activity and durability by carbon semi-coated titania nanorods for proton exchange membrane fuel cells
No full textWe report a simple, scalable approach to improve interfacial characteristics of carbon semi-coated titania
nanorods-supported-Pt with superior peak power density as compared to Pt/C with thin metal loading of
150 mg cm�2. Thin layer of carbon coated titania nanorod is synthesized by hydrothermal method. Carbon
coated titania nanorods boosts the Pt oxygen reduction reaction activity than carbon. The crystal
structure, dispersion of platinum nanoparticles, surface morphology and oxidation state are studied by
X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy, respectively.
Studies using conventional three electrode setup shows that Pt/CCT-30 retains 48% of initial electrochemical
surface area even after 40,000 potential cycles between 0.6 and 1.2 V. The solid fuel cell mode
accelerated stress durability studies show that thin layer of carbon coated titania nanorods-Pt (Pt/CCT 30)
significantly enhances stability and preserves 75% of initial fuel cell performance even after 10,000
potential cycles between 1 and 1.5 V. In comparison, only 20% of performance is retained for Pt supported
on carbon after 3000 cycle
Online monitoring of fuel starvation and water management in an operating polymer electrolyte membrane fuel cell by a novel diagnostic tool based on total harmonic distortion analysis
No full textThe present study deals with a novel diagnostic tool for fuel and water management problems by analyzing the
harmonics on an operating polymer electrolyte membrane fuel cell. In this method, a low frequency signal is
applied to the fuel cell and the total harmonic distortion contained in the resulting signal is observed under
different conditions. The total harmonic distortion is used to monitor and identify the conditions online such as
anode drying, anode flooding, hydrogen starvation and cathode flooding prevailing in the cell. This is done by
identifying a set of indicator frequencies correspond to the aforementioned critical conditions. Through empirical studies, it is shown that frequency responses lead to a high total harmonic distortion value indicating
critical conditions and provide an accurate diagnostic method to detect an even slightly degraded state. These
results successfully demonstrate the promise of the proposed method in overcoming performance losses by
efficient online monitoring of fuel cells. The relation between the health of the fuel cell and the variations in the harmonics present in the studied signal is characterized and utilized for the diagnostic studies of polymer electrolyte membrane fuel ce
pH dependent CO adsorption and roughness-induced selectivity of CO2 electroreduction on gold surfaces
No full textGold belongs to the category of metal electrocatalysts for CO2 reduction reaction (CO2RR) producing CO
as a major product due to its inability to bind CO. In this work, we found that when the interfacial pH
becomes alkaline, CO, the major product of CO2RR, interacts with gold surfaces to produce minor
products like formate and methanol. The course of product formation and CO adsorption on gold was
explored by their oxidative voltammetric responses obtained immediately after CO2RR in the forward
cathodic scan and SECM studies provided more insights into the effect of interfacial pH on product
selectivity. The electrode roughness was found to change the interfacial pH gradients as a result of
microheterogeneity of surfaces. The roughness of gold surface was systematically changed from
smoothened surface to nanoporous (highly rough) surface. NMR spectroscopic analysis pointed to the
presence of methanol and formate being formed on nanoporous Au (np- Au) in significant amounts.
Formate production was found increasing as a result of changes in the interfacial pH
Highly fluorescent carbon quantum dots-Nafion as proton selective hybrid membrane for direct methanol fuel cells
No full textHighly fluorescent carbon quantum dots-Nafion as proton selective hybrid membrane for direct methanol fuel cell
Fabrication of Co-Ni alloy nanostructures on copper foam for highly sensitive amperometric sensing of acetaminophen
No full textIn this work, electrodeposition of Co-Ni alloy nanostructures was performed on copper foam and directly applied as an electrocatalyst for the electrooxidation of acetaminophen (Paracetamol) and its detection. The surface morphology and the elemental composition were investigated using SEM and EDX analyses respectively. The
observed morphology was similar to nano cones that are uniformly grown on the electrode surface. EDX analysis
also confirmed the presence of both cobalt and nickel in the electrodeposit. The preferred orientation lies in
(002) and (110) planes of cobalt and nickel respectively that confirmed the formation of alloy. Electrooxidation
of acetaminophen was carried out using cyclic voltammetric method in 0.1M NaOH solution. On addition of
acetaminophen, an apparent anodic oxidation current enhancement was observed with lesser overpotential than
cobalt and nickel electrodes which revealed the excellent electrocatalytic activity of the material. Interference
studies also revealed the good selectivity for acetaminophen even in the presence of some interfering species.
The reproducibility and stability was checked for the proposed Co-Ni alloy modified electrode. The analytical
applicability was examined using the commercial paracetamol tablets and the recovery results were also good.
The above results revealed that Co-Ni modified electrode on copper foam is a suitable candidate for electrochemical detection of acetaminophen
Molecular dynamics simulation approach to explore atomistic molecular mechanism of peroxidase activity of apoptotic cytochrome c mutants
No full textMutations in cytochrome c (Cyt c) have been reported in tuning peroxidase activity, which in-turn cause Cyt c
release from mitochondria and early apoptosis. However, the molecular tuning mechanism underlying this activity remains elusive. Herein, multiple 20 ns molecular dynamics (MD) simulations of wild type (WT), Y67F and
K72W mutated Cyt c in aqueous solutions have been carried out to study how the changes in structural features
alters the peroxidase activity of the protein. MD simulation results indicate that Y67F mutation caused, (i)
increased distances between critical electron-transfer residues, (ii) higher fluctuations in omega loops, and (iii)
weakening of intraprotein hydrogen bonds result in open conformation at heme crevice loop in Cyt c leading to an
enhanced peroxidase activity. Interestingly, the aforementioned structural features are strengthened in K72W
compared to WT and Y67F, which triggers K72W mutated Cyt c into a poor peroxidase. Essential dynamics results
unveil that first two eigenvectors are responsible for overall motions of WT, Y67F and K72W mutated Cyt c. This
study thus provides atomic level insight into molecular mechanism of peroxidase activity of Cyt c, which will help in designing novel Cyt c structures that is more desirable than natural Cyt c for biomedical and industrial
processe
Multiphasic inhibition of mild steel corrosion in H2S gas environment
No full textCompounds like Octylpalmamide (OTP), Octylsteramide (OTS), Octylcaprylamide
(OTC), Octylbenzamide (OTB) and one complex compound Dicyclohexylaminebenzotriazole
(DCHAB) were synthesized and characterized by Fourier Transform infrared spectroscopy (FTIR).
These synthesized compounds were drawn as volatile corrosion inhibitor (VCI) in H2S gas
environment on mild steel (MS) at 323 K. Surface morphology and elemental analysis have been
examined by Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy
(EDX) respectively. Various studies like weight loss, potentiodynamic polarization and electrochemical
impedance spectroscopy (EIS) were used for evaluating corrosion rate, inhibitor behaviour
and change in charge transfer resistance (Rct) value, respectively. All the above experiments proved
that DCHAB was the most efficacious corrosion inhibitor. Adsorption behaviour of the inhibitor
was evaluated and it obeys Langmuir adsorption isotherm
Symmetric supercapacitor performances of CaCu3Ti4O12 decorated polyaniline nanocomposite
No full textTo explore the possibility of developing an electrode material with better supercapacitor performances, a
composite of polyaniline (PANI) and varying amount of CaCu3Ti4O12 (CCTO) was synthesized using a
simple technique involving in-situ polymerization of aniline using ammonium persulphate as oxidant.
The pristine PANI and the composite were characterized using X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscope
(SEM) equipped with energy dispersive X-ray analysis (EDAX) and transmission electron microscope
(TEM). The electrochemical activities of the PANI/CCTO nanocomposites were examined in 1M H2SO4 in a
three electrode assembly. It turned out that the specific capacity of the PANI can be largely tuned by
making composite with the inorganic filler, CCTO. The composite consisting of just 5 wt % CCTO in PANI
(PC5) exhibited the highest electrochemical activity with excellent stability compared to other compositions as well as the pristine PANI. A symmetric supercapacitor device consisting of the PC5 composite as
both positive and negative electrodes that were fabricated have exhibited energy density of 30 W h kg�1
with an excellent power density of 20 kW kg�1
. Glowing of an LED using the proto-type solid-state
symmetric device was demonstrate
Investigation on the effect of organic dye molecules on capacitive deionization of sodium sulfate salt solution using activated carbon cloth electrodes
No full textCapacitive deionization (CDI) is an emerging electrochemical desalination technique for the energyefficient
removal of dissolved ions from aqueous solution. This is a first research attempt which describes
the influence of dye molecules on capacitive deionization of salt solution. In this regard, a CDI flow cell
has been fabricated and tested in order to scrutinize the electrosorptive removal of three different dye
molecules such as amido black 10B (AB) (acidic dye), eosin yellow (EY) (neutral dye) and methyl violet
(MV) (basic dye) from synthetic aqueous solutions. The electrosorption capacitance was analyzed by
cyclic voltammetry cell and CDI flow cell using activated carbon cloth (ACC) electrodes with 1 cm2 and
24 cm2 surface areas respectively. The capacitance values of 106 and 99 F/g correspondingly were obtained
for a steady-state CV and CDI flow cell with 50mM Na2SO4 electrolyte solution. In addition to this,
the dye removal efficiency was also examined by a CDI flow cell for the solution containing 10 ppm of dye
and 500 ppm of Na2SO4. The experimental results substantiate that EY exhibits strong adsorption during
charging and strong desorption during discharge cycle when compared with other two dye molecules
(AB & MV). Conclusively, electrosorption of dye molecules at the carbon cloth electrodes surface was
found in the following order: EY > AB > MV