The electrooxidation of chemisorbed co on polycrystalline platinum: A mechanistic interpretation of the anodic current peak multiplicity

The electrooxidation of CO on polycrystalline Pt in 1 M HClO4 at 23°C under potentiodynamic conditions exhibits a double current peak. Whether a single or a double current peak is formed depends to a great extent on the amount of CO surface coverage. The present report attempts to explain the behaviour of the electrochemical reaction in terms of a single model involving the participation of two CO adsorbed states on polycrystalline Pt.Instituto de Investigaciones Fisicoquímicas Teóricas y AplicadasFacultad de Ciencias Exacta

Modulated reflectance spectroscopy and voltammetry of the sulphide/gold system

The electroadsorption of sulphide species on gold and the growth of sulphur multilayers have been investigated by optical and electrochemical techniques in sodium tetraborate buffer as the supporting electrolyte (pH 7.0 and 9.2) at 25°C. Differential reflectance spectra indicate that the adsorption of sulphide begins inside the hydrogen evolution reaction (HER) region. The HER is catalysed by the presence of sulphide species on the electrode. During the growth of sulphur multilayers, soluble polysulphide species can be optically detected either as intermediates under diffusion-controlled kinetics or as products of a chemical reaction between sulphide ions and the deposited sulphur layer. The steep fall in the integral reflectance at 0.4 V (vs. SHE) is interpreted through the incorporation of light-absorbing polysulphides into the structure of the deposited sulphur layer.Instituto de Investigaciones Fisicoquímicas Teóricas y AplicadasFacultad de Ciencias Exacta

Potentiodynamic current/potential characteristics of theoretical mechanisms related to the electrochemical formation and electroreduction of monolayer films on inert electrodes

The current/potential curves of various mechanisms related to the electrochemical formation and electroreduction of monolayer films on inert electrodes, involving a single surface covering species and two surface covering species are presented. The potential perturbation functions consist both of single either linear or triangular potential sweeps and of triangular modulated linear potential sweeps. A comparison of the theoretical Eli displays obtained with the different potential perturbation techniques is given for the various reaction pathways presented.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Potentiodynamic current/potential characteristics of theoretical mechanisms related to the electrochemical formation and electroreduction of monolayer films on inert electrodes

The current/potential curves of various mechanisms related to the electrochemical formation and electroreduction of monolayer films on inert electrodes, involving a single surface covering species and two surface covering species are presented. The potential perturbation functions consist both of single either linear or triangular potential sweeps and of triangular modulated linear potential sweeps. A comparison of the theoretical Eli displays obtained with the different potential perturbation techniques is given for the various reaction pathways presented.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

The electrooxidation of chemisorbed co on polycrystalline platinum: A mechanistic interpretation of the anodic current peak multiplicity

The electrooxidation of CO on polycrystalline Pt in 1 M HClO4 at 23°C under potentiodynamic conditions exhibits a double current peak. Whether a single or a double current peak is formed depends to a great extent on the amount of CO surface coverage. The present report attempts to explain the behaviour of the electrochemical reaction in terms of a single model involving the participation of two CO adsorbed states on polycrystalline Pt.Instituto de Investigaciones Fisicoquímicas Teóricas y AplicadasFacultad de Ciencias Exacta

Modulated reflectance spectroscopy and voltammetry of the sulphide/gold system

The electroadsorption of sulphide species on gold and the growth of sulphur multilayers have been investigated by optical and electrochemical techniques in sodium tetraborate buffer as the supporting electrolyte (pH 7.0 and 9.2) at 25°C. Differential reflectance spectra indicate that the adsorption of sulphide begins inside the hydrogen evolution reaction (HER) region. The HER is catalysed by the presence of sulphide species on the electrode. During the growth of sulphur multilayers, soluble polysulphide species can be optically detected either as intermediates under diffusion-controlled kinetics or as products of a chemical reaction between sulphide ions and the deposited sulphur layer. The steep fall in the integral reflectance at 0.4 V (vs. SHE) is interpreted through the incorporation of light-absorbing polysulphides into the structure of the deposited sulphur layer.Instituto de Investigaciones Fisicoquímicas Teóricas y AplicadasFacultad de Ciencias Exacta

The electrooxidation of CO: a test reaction in electrocatalysis

This review paper aims to show how the electrochemical behaviour of CO plays a key role in the understanding of the reaction mechanism of many electrocatalytic oxidations of small organic molecules. For that purpose, the adsorption of CO on noble metal electrodes, eventually modified by foreign metal adatoms, is reviewed, taking into account both experimental (electrochemical and spectroscopic techniques) and theoretical (Extended Hückel Model) approaches. Data from the gas phase-solid metal interface are also considered.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA)Facultad de Ciencias Exacta

Solid films and interfaces in fused salt electrochemical systems

The present review deals with two main aspects of the electrochemical formation and characteristics of thin solid films. The first shows, through a few typical examples, that these films occur at different metal-molten electrolyte interfaces and that their average composition depends on how they are formed, i.e. anodically or cathodically. The second aspect deals with the kinetics of thin film formation. The first reaction, which has undoubtedly been the more thoroughly investigated, involves the early stages in the formation of an oxygen monolayer on platinum in molten alkali bisulphates. The electrochemical features of this interface are also found at other metal-molten electrolyte interfaces. Finally, the kinetics of multilayer thin film electroformation are presented to show that the nucleation and film growth laws derived for film formation at metal-solution interfaces also apply to metal-melt interfaces.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

The electrooxidation of CO: a test reaction in electrocatalysis

This review paper aims to show how the electrochemical behaviour of CO plays a key role in the understanding of the reaction mechanism of many electrocatalytic oxidations of small organic molecules. For that purpose, the adsorption of CO on noble metal electrodes, eventually modified by foreign metal adatoms, is reviewed, taking into account both experimental (electrochemical and spectroscopic techniques) and theoretical (Extended Hückel Model) approaches. Data from the gas phase-solid metal interface are also considered.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA)Facultad de Ciencias Exacta

Kinetics of the oxygen evolution reaction on rhodium electrodes with different electrocatalytic activity

It has recently been demonstrated that the potentiodynamic behaviour of Rh/H2SO4(aq) interphases in the potential range of the thermodynamic stability of bulk water is associated with at least two-well defined and different electrochemical characteristics of rhodium, which were referred to as Aand B-type Rh electrodes. The aim of the present report is to show the electrocatalytic difference of A- and B-type electrodes for the 02 evolution reaction, on the basis that the corresponding structures of the electrodes remain stable during the time the electrochemical measurements last.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada