Journal of Electroanalytical Chemistry 

Abstract: The equation of the linear potential sweep voltammogram is derived for any degree of reversibility of the electrochemical reaction for the following methods: surface voltammetry when both the oxidized and the reduced forms are strongly adsorbed, and a Langmuir isotherm is obeyed, thin layer voltammetry, and linear potential sweep coulometry. The results are expressed in one mathematical form valid for the three cases. The transfer coefficient and the rate constant of the electrochemical reaction can be deduced from an experimental study of the variations of the peak potentials as a function of the sweep rate.

Abstract: In this work we have verified the remarkable sensitivity of Raman spectroscopy for the study of adsorbed pyridine on a silver surface, and extended its applicability to other nitrogen heterocycles and amines. New bands in the scattering spectrum of adsorbed pyridine have been characterized, which were not previously reported, as well as the Raman intensity response of all the surface pyridine bands as a function of electrode potential. As a result of these experiments, we have proposed a model of the adsorbed species for pyridine in which the adsorption is anion induced, leading to an axial end-on attachment to the electrode surface. The ability to obtain resonance Raman spectra with good signal-to-noise with laser powers less than 1.0 mW, reported here for the first time, opens up possibilities of surface Raman studies with relatively inexpensive laser systems. As laser power requirements are relaxed, reliability is improved, and greater tuning ranges can be achieved for wavelength dependent studies. We previously demonstrated the potential of resonance Raman spectroscopy for monitoring solution kinetic behavior [2], and now have shown that NR as well as RR spectroscopy has sufficient sensitivity to extend the studies of kinetic processes to include those occurring at electrode surfaces.

Abstract: The electrical double-layer at a solid electrode does not in general behave as a pure capacitance but rather as an impedance displaying a frequency-independent phase angle different from 90°. Ways are indicated how to analyse the interfacial impedance if such a complication arises in the presence of a faradaic process, both on the supposition that the double-layer behaviour is due to surface inhomogeneity and on the supposition that it is a double-layer property per se. As examples, the equations derived are successfully applied to a totally irreversible and an ac quasi-reversible electrode process at a gold electrode.

Abstract: In this paper, density functional theory (DFT) calculations are performed to analyze the electrochemical water-splitting process producing molecular oxygen (O 2 ) and hydrogen (H 2 ). We investigate the trends in the electro-catalytic properties of (1 1 0) surfaces of three rutile-type oxides (RuO 2 , IrO 2 , and TiO 2 ). The two first of these oxide anodes show lower O 2 -evolving over-potentials than metal anodes, due to weak O binding but strong hydroxyl (HO ∗ ) binding on the surface. Furthermore, the binding energies of O, HO, and HOO on the (1 1 0) surfaces fulfill universal linear relations similar to those found on metal surfaces.

Abstract: Summary The effects of a strong adsorption of the depolarizer and/or of the product of the electrochemical reaction on the currents obtained in polarography and in linear potential sweep voltammetry (l.p.s.v.) are considered. (a) A study of the surface electrochemical reaction (reaction of molecules in the adsorbed state) is presented. Mathematical expressions are derived for the current when the reaction is reversible (Brdicka prewaves or postwaves) for polarography and l.p.s.v. The case where the product of the reaction undergoes an irreversible chemical reaction of the first or second order in l.p.s.v. has been treated. Experimental examples are given: the theory accounts for the characteristics of the Brdicka prewaves and postwaves and of the adsorption peaks obtained in l.p.s.v. (b) The electrochemical process is modified by a film of adsorbed molecules (autoinhibition or autocatalysis). Three types of autoinhibition are considered: (I) The inhibiting film is constituted of the molecules of the depolarizer itself. (II) The molecules of the film result from a chemical reaction which occurs parallel with the inhibited electrochemical reaction. (III) The film is made of the final product of the inhibited electrochemical reaction. Mathematical expressions for the i−t curves and for the polarograms have been derived and experimental examples are given. In case III, autoinhibition waves similar in shape to Brdicka prewaves are often observed (pseudo-prewaves); criteria permitting a distinction to be made between prewaves and pseudo-waves are discussed. The case of an autocatalysis by the product of the reaction has been treated; an experimental example is given. The equations of the i−t curves (polarography) and i−E curves (l.p.s.v.) have also been calculated when the electrochemical reaction is irreversible. These equations are obeyed for small coverages. When the film of the depolarizer is compact anomalies appear, which are due to interactions between the molecules.