M.V. Sangaranarayanan

The design of electrochemical supercapacitors exploiting the concept of underpotential deposition (UPD) is demonstrated using the UPD of thallium on silver as an illustrative example. The specific capacitance is deduced as 3.45×102 Farads g-1 from cyclic voltammetric studies employing the roughness factor for calculating the electroactive surface area.

A new analysis of the metal/electrolyte interface using jellium model for metal surfaces and Bethe approximation for dipolar interactions is carried out. The total surface energy taking into account the metal-solvent interactions is then solved using a one-parameter family of trial functions for the electronic density profile, and a systematic investigation of the metal-solvent bond length (X1) and its dependence on electrode charge density (OM) is presented. The crucial role played by x1 in double-layer analysis is also pointed out using the variation of inner layer capacitance with OM at the Hg/NaF interface. The model is then used to analyze the effect of temperature, bulk electron density of the metal, and electron-ion coupling terms using Ashcroft pseudopotential on the capacitance-potential plots. The position of the image plane and its variation with electric field, electron density of metals, etc., have also been outlined. The influence of external field on work function changes pertaining to solvent adsorption at electrochemical interfaces is discussed.

The specific capacitance of polyaniline (PANI) deposited potentiodynamically on a stainless steel (SS) substrate, in the presence of p-toluene sulphonic acid (PTS) is estimated. Cyclic voltammetric experiments, galvanostatic charge-discharge studies and impedance analysis are carried out in order to investigate the applicability of the system as an electrochemical supercapacitor. Fourier transform infrared (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques are employed for characterization of the electrode. © 2006 Elsevier B.V. All rights reserved.

We report an efficient methodology for exactly enumerating conformations of lattice proteins, taking into account the self-avoiding nature. These self-avoiding walks in square and simple cubic lattices take into account, the detailed paths by which a destination site can be reached from a starting site. The strategy employing Java programming enables the exact enumeration for very large lattice sizes. The estimation of these conformations is helpful in designing the protein sequences pertaining to Hydrophobic-Polar models.

In recent years, there has been significant interest in the design of electrodes for enhanced electrochemical sensing platforms towards selective and sensitive detection of biological steroid hormones. We report here a facile, template-free electrodeposition of tin nanorods on glassy carbon electrodes and analyse its efficacy for the sensing of progesterone using voltammetric and amperometric techniques. The physicochemical properties of the tin-nanorods modified glassy carbon electrodes are characterized by electron microscopic studies, UV–vis spectral analysis, X-ray diffraction and electrochemical impedance spectroscopy. The mechanism involved in the reduction of progesterone has been elucidated using quantum chemical calculations and the influence of the cationic surfactant (cetyltrimethylammonium bromide) is pointed out. The estimation of progesterone is carried out with differential pulse voltammetry and amperometry. The electrode exhibits an impressive response towards the sensing of progesterone in terms of higher sensitivity, linear calibration regime varying from 40 to 600 μM with the lowest detection limit being 0.12 μM. The effect of other interfering agents such as testosterone, 17β-estradiol, creatinine, uric acid and ascorbic acid is also analysed using differential pulse voltammetry. The analysis of progesterone assay in commercial pharmaceutical formulations has also been carried out and reveals a satisfactory agreement.

The analysis of transient chronoamperometric current response for various ultramicroelectrode geometries is carried out by solving the mixed boundary value problem for short and long time regimes. A two-point Padé approximant valid for entire time domain is developed. Tabular compilations of dimensionless current for ring and disc electrodes are reported.

An explicit expression for the exchange current density in terms of work function of the metal surface, surface potential of the reactants and products, and solvation energies was derived. The usefulness of the expression was demonstrated for a ferric/ferrous reaction whose i0 values have been reported for a variety of electrodes using experimental data and theoretical calculations.

A new parametric relation for hardness incorporating the surface potential of the metal and work function was derived. Hydrogen evolution and ferric/ferrous redox reactions were considered as examples to extract chemical hardness from electrode kinetic data.

A systematic way of distinguishing stepwise and concerted mechanisms in reductive cleavage reactions has been formulated involving current function analysis of the voltammetric data. The electrochemical reductive cleavage of the carbon-iodine bond in 1,3-dichloro-2-iodobenzene has been analyzed from a mechanistic point of view to illustrate the methodology. 1,3-Dichloro-2- iodobenzene undergoes an initial stepwise electron transfer obeying quadratic activation-driving force relationship. The current function analysis yields the reorganization energy for the reduction of 1,3-dichloro-2-iodobenzene and the results have been verified independently using convolution potential sweep voltammetry. © 2004 Elsevier Ltd. All rights reserved.

A novel method of deducing the parameters of electron density profiles pertaining to the theoretical re-construction of X-ray reflectivity data of liquid metals is proposed and the inter-dependence of various parameters of the electron density is indicated. The crucial role played by the diffusion coefficient, viscosity and critical temperature of the metals in dictating the correlation lengths is pointed out. The applicability of the methodology is demonstrated for the experimental data on the X-ray reflectivity of Ga, In and K. © 2009 Elsevier B.V. All rights reserved.