Future tasks in interfacial electrochemistry and surface reactivity

Interfacial electrochemistry is a main part of Physical Electrochemistry, which is developing in several directions. In this respect, this note will reflect my personal views in the “to do” list of topics related to well-defined interfacial electrochemistry and its application to the understanding of electrocatalytic reactivity, deliberately limited to single-crystal platinum model electrodes in water electrolyte solutions. Several points are related to ongoing research and others have been suggested in meetings. Because of that, the text has a taste of déjà vu. References are a limited selection of examples for the interested readers.Financial support from MICINN-FEDER (project CTQ2016-76221-P) is greatly acknowledged

Flexible link arm with a passive gravity compensation mechanism: design and modeling

[Abstract] The gravity compensation of flexible link manipulators using mechanisms based on counterweights has been previously studied in the research literature. However, as far as we are concerned, no attempt has been done to study the difficulties and benefits of constructing mechanisms for the same purposes based on springs. This paper presents a gravitational mechanism based on springs for a single-link flexible arm. In specific, we address the mechanical design of the mechanism and the dynamic modeling of the resulting system. To assess the effectiveness of the mechanism and the validity of the dynamic model, we present experimental results.[Resumen] La compensación por gravedad de los manipuladores de enlace flexible que utilizan mecanismos basados en contrapesos se ha estudiado previamente en la literatura de investigación. Sin embargo, en lo que a nosotros respecta, no se ha hecho ningún intento de estudiar las dificultades y los beneficios de construir mecanismos para los mismos propósitos basados en resortes. Este artículo presenta un mecanismo gravitatorio basado en resortes para un brazo flexible de un solo enlace. En concreto, abordamos el diseño mecánico del mecanismo y el modelado dinámico del sistema resultante. Para evaluar la efectividad del mecanismo y la validez del modelo dinámico, presentamos resultados experimentales.Ministerio de Economía y Competitividad; DPI2016-80547-

Editorial

resume

On the activation energy of the formic acid oxidation reaction on platinum electrodes

A temperature dependent study on the formic acid oxidation reaction has been carried out in order to determine the activation energy of this reaction on different platinum single crystal electrodes, namely Pt(1 0 0), Pt(1 1 1), Pt(5 5 4) and Pt(5 4 4) surfaces. The chronoamperometric transients obtained with pulsed voltammetry have been analyzed to determine the current densities through the active intermediate and the CO formation rate. From the temperature dependency of those parameters, the activation energy for the direct reaction and the CO formation step have been calculated. For the active intermediate path, the activation energy are in the range of 50–60 kJ/mol. On the other hand, a large dependence on the electrode potential is found for the activation energy of the CO formation reaction on the Pt(1 0 0) electrode, and the activation energy values for this process range between 20 and 100 kJ/mol. These results have been explained using a reaction mechanism in which the oxidation of formic acid requires the presence of a pre-adsorbed anion on the electrode surface

Effects of the anion adsorption and pH on the formic acid oxidation reaction on Pt(111) electrodes

The effects of solution pH and anion adsorption for the formic acid oxidation reaction on the Pt(111) electrode have been examined using electrochemical techniques. Regarding the pH effects, it has been found that oxidation currents for this reaction increase with pH, which indicates that solution formate is involved in the reaction mechanism. Unexpectedly, the adsorption of sulfate on the Pt(111) electrode has a positive effect on the oxidation of formic acid, which also suggests that adsorbed anions are also involved in the mechanism. The activation energy calculated from temperature dependent measurements diminishes with the solution pH and also in the presence of adsorbed sulfate. These measurements corroborate the involvement of solution formate and anions in the oxidation mechanism. Using these results, a rate equation for the oxidation of formic acid is proposed. The current values calculated from this equation are in very good agreement with the experimental currents in perchloric acid solutions.This work has been financially supported by the MICINN (Spain)(project CTQ2010-16271) and Generalitat Valenciana (project PROMETEO/2009/045, FEDER)

Changes in tobacco imagery and smokers’ depiction in Spanish top-grossing films before and after the implementation of a comprehensive tobacco control policy in Spain

INTRODUCTION As more restrictions on tobacco marketing communication are implemented, tobacco marketing has persisted through smoking in films. Our aims were to assess changes in tobacco imagery exposure in Spanish top-grossing films before and after the banning of tobacco advertising in Spain, and to determine whether the depiction of smoking characters has changed over the years. METHODS A repeated cross-sectional study measured the tobacco content in the 10 Spanish top-grossing films in 2005, 2010 and 2015 (n=30) before and after a complete tobacco advertising ban. We conducted a descriptive and regression analysis of changes in tobacco impressions by year. RESULTS The 30 films contained 1378 tobacco occurrences (90.2% positive for tobacco) with a median length of eight seconds onscreen. Total tobacco occurrences deemed positive for tobacco interests significantly increased in 2010 and 2015 compared to 2005. However, we observed decreased odds of tobacco brands appearances (OR=0.25; p<0.001) in 2010 and of implied tobacco use (OR=0.44; p=0.002), and tobacco brands appearances (OR=0.36; p<0.001) in 2015 compared to 2005. There was a change of pattern in the type of role smokers played from a leading role to a supporting one (p<0.001). The population reach of positive for tobacco occurrence in Spanish top-grossing films decreased from 15.9 (95% CI: 15.86–15.86) per 1000 spectators in 2005 to 0.8 (95% CI: 0.82–0.82) in 2015. CONCLUSIONS The implementation of a ban on complete tobacco product advertising was followed by a decrease in tobacco incidents across top-grossing Spanish films. Yet, exposure to smoking in films is still unacceptably high.Ministry of Universities and Research from the Government of Catalonia 2021SGR0090

A new truck prototype for transporting flexible manipulators

[Resumen] Este trabajo se ocupa del diseño mecánico y la descripción de los diferentes componentes de una base móvil novedosa para un manipulador móvil flexible. Un manipulador móvil flexible normalmente se compone de múltiples enlaces flexibles montados en una plataforma móvil. Este trabajo se centra en la descripción de la plataforma móvil. La plataforma móvil de este trabajo tiene dos configuraciones diferentes para llevar a cabo diferentes tareas. Además, en este trabajo se muestran algunas hipótesis y resultados experimentales como un primer paso para poder obtener un modelo cinemático del sistema más adelante.[Abstract] This work is concerned with the mechanical design and the description of the different components of a novel mobile base for a flexible mobile manipulator. A flexible mobile manipulator is normally composed of multiple flexible links mounted on a mobile platform. This work is focused on the description of the mobile platform. The mobile platform of this work has two different configurations in order to carry out different tasks. Also, some hypothesis and experimental results are shown in this work as a first step to be able to obtain a kinematic model of the system later.Ministerio de Educación, Cultura y Deporte; FPU14/02256Ministerio de Economía, Industria y Competitividad; DPI2016-80547-

Role of oxygen-containing species at Pt(111) on the oxygen reduction reaction in acid media

The oxygen reduction reaction (ORR) is one of the fundamental reactions in electrochemistry and has been widely studied, but the mechanistic details of ORR still remain elusive. In this work, the role of electrochemically oxygenated species, such as adsorbed hydroxide, OHads, adsorbed oxygen, Oads, and Pt(111) oxide, PtO, in the ORR dynamics is studied by employing electrochemical techniques, i.e., combining rotating disk mass-transport control with potential sweep rate perturbation. In this framework, a reduction peak at 0.85 V, E ORR, is detected. This peak shows a different electrochemical dynamics than that of Pt(111) oxides. The data analysis suggests that neither OHads nor Oads are the main bottleneck in the mechanism. Instead, results support the reduction of a soluble intermediate species as the rate determining step in the mechanism. On the other hand, PtO species, which are generated at relatively high potentials and are responsible of surface disordering, strongly inhibit the ORR as long as they are adsorbed in the electrode surface.This study has been carried out in the framework of the European Commission FP7 Initial Training Network “ELCAT,” Grant Agreement No. 214936–2. Supports from the Spanish MINECO though project CTQ2013–44083-P and GV through PROMETEOII/2014/013 (FEDER) are greatly acknowledged

Thermodynamic properties of hydrogen–water adsorption at terraces and steps of Pt(111) vicinal surface electrodes

In this work, the effect of temperature on the adsorption states of Pt(111) vicinal surface electrodes in perchloric acid is studied through a thermodynamic analysis. The method allows calculating thermodynamic properties of the interface. In this framework, the concept of the generalized isothermand the statistical thermodynamics description are applied to calculate formal entropies, enthalpies and Gibbs energies,ΔGi0, of the adsorption processes at two-dimensional terraces and one-dimensional steps. These values are compared with data from literature. Additionally, the effect of the step density onΔGi0 and on the lateral interactions between adsorbed species,ωij, at terraces and steps is also determined. Calculated ΔGi0 , entropies and enthalpies are almost temperature-independent, especially at steps, but they depend on the step orientation. In contrast,ΔGi0 and ωij at terraces depend on the step density, following a linear tendency for terrace lengths larger than 5 atoms. However, while ΔGi0 increases with the step density, ωij decreases. Results were explained by considering the modification in the energetic surface balance by hydrogen, Hads, andwater,H2Oads, co-adsorption on the electrode, which in turn determines the whole adsorption processes on terraces and steps.This study has been carried out in the framework of the European Commission FP7 Initial Training Network “ELCAT”, Grant Agreement No. 214936-2. Support from the Spanish MINECO though project CTQ2013-44083-P and GV through PROMETEOII/2014/013 (FEDER) are greatly acknowledged

Oxygen reduction on nanostructured platinum surfaces in acidic media: Promoting effect of surface steps and ideal response of Pt(1 1 1)

In this paper, the role of surface steps on the electrocatalytic activity of platinum nanostructured surfaces for the oxygen reduction reaction (ORR) in acidic medium is evaluated by using stepped surfaces of structure Pt(S)[n(1 1 1) × (1 1 1)] with large terraces (20 ≤ n ≤ 50). It is realized that the inclusion of an even low amount of surface steps enhances the ORR, and linear activity trends are measured when currents at constant potential are plotted vs. the step density. As a consequence, an ideal ORR curve for a defect-free Pt(1 1 1) surface is extrapolated at zero defect density from experimental data and can be compared to that of a quasi-perfect Pt(1 1 1) electrode. It is clearly shown that surface steps promote the electrode activity toward ORR in acid medium. Results are discussed in light of available theoretical and experimental data.This work has been financially supported by a grant from COLCIENCIAS and the Universidad Nacional de Colombia in the framework of the National Program of Formation in Innovation Leaders (Contract No. 472 of 2007). Support from the Spanish MICYNN though project CTQ2010-16271 and GV through PROM-ETEO/2009/045 (FEDER) are also greatly acknowledged