Las energías renovables son una alternativa segura al problema socio-económico que experimenta la región del Mercosur. El hidrógeno es el acumulador ideal para la energía de origen eolo-eléctrica. Si bien el hidrógeno es el elemento más abundante en la naturaleza, requiere energía para su producción, pues raras veces se lo encuentra libre. Por electrólisis se obtiene hidrógeno puro. Es por ello que en las regiones del Mercosur la conjunción ideal que debe ser explotada es la unión de dos elementos, el viento y el hidrógeno, por cuanto la utilización de celdas de combustible permite obtener energía eléctrica estable en lugares aislados a partir de energía eólica, que es fluctuante. También se están desarrollando métodos de obtención de hidrógeno por reformado de gas natural o biodiesel con muy buenos resultados. Por lo tanto, el presente trabajo tiene como común denominador estudios e investigaciones sobre la energía del hidrógeno y sus consecuencias benéficas en relación con los recursos renovables y no renovables y con la reducción del impacto ambiental durante su utilización. El carácter multidisciplinario de este trabajo ha permitido abordarlo desde un aspecto básico y también tecnológico contemplando distintas posibilidades, como la producción de electricidad en celdas de combustible y la producción de hidrógeno empleando energía eólica y su impacto en la región.

Renewable energies are a safe alternative to the socioeconomic problem that the Mercosur region is experiencing. Hydrogen is the ideal medium for wind and electric energy storage. Although hydrogen is the most abundant element in nature, it requires energy for its production, because it seldom occurs free. Pure hydrogen is obtained by water electrolysis. It is for that reason that in the Mercosur regions the ideal scenario that must be exploited is the combination of two elements, wind and hydrogen, inasmuch as the use of fuel cells allows obtaining steady electric energy in isolated places from wind energy, which is intermittent. Methods for obtaining hydrogen by the reforming of natural gas or biofuel with very good results are also being developed. Therefore, the present work focuses on both studies and research on hydrogen energy and its beneficial consequences in relation to renewable and non-renewable resources, and to the mitigation of the environmental impact during its use. The multidisciplinary character of this work has allowed approaching it from a basic and also technological aspect considering different possibilities, such as electricity generation in fuel cells and hydrogen production using wind energy, and their impact on the region.

The electroadsorption and electroreduction of carbon dioxide, and the subsequent electrooxidation of reduced carbon dioxide was studied on polycrystalline and electrofaceted Pt and on polycrystalline Rh electrodes. The influence of the adsorption potential and the adsorption time was established. Combining voltammetric charge measurements and differential electrochemical mass spectrometry (DEMS) analysis, three adsorbates were tentatively identified, namely COOH and CO in bridge and linear configurations on Pt, and COH in triple and single adsorption configurations on Rh. By applying medium frequency potential routines on the Pt-adsorbate/sulphuric acid interface, the existence of equilibrium between adsorbates was demonstrated.

Se estudia la electroadsorción y la electrorreducción de dióxido de carbono como así también la electrooxidación del dióxido de carbono reducido sobre Pt policristalino y electrofacetado y sobre Rh policristalino. Se determina la influencia del potencial y del tiempo de adsorción. Mediante el empleo de técnicas combinadas voltamperométricas y de espectrometría de masa diferencial (DEMS), se identificaron tres adsorbatos posibles sobre Pt, COOH y CO en configuración lineal y puente, y dos sobre Rh, COH en configuraciones de adsorción simple y triple. Mediante la aplicación de perturbaciones de potencial a la interfase Pt-adsorbato/ácido sulfúrico acuoso, se demuestra la existencia de un equilibrio entre los adsorbatos.

Carbon pencil electrodes are proposed as supporting material for the fabrication of disposable devices through surface modification by bismuth plating and polyaniline formation. The surface characteristics were assessed by fractal analysis under semi-infinite linear diffusion employing a soluble molecular probe, and scanning electron microscopic analysis. The results indicate that the surface topography for bismuth-modified electrodes corresponds to a 2-dimensional smooth surface, while for polyaniline-modified electrodes, a surface fractal dimension of 2.76 was obtained. These topographic characteristics indicate that bismuth-modified carbon electrodes are suitable for anodic stripping analysis, and polyaniline ones, due to the surface irregularities, may result a good supporting material for biomolecules attachment.

Foram aplicadas rotinas combinadas de potencial, envolvendo varreduras voltamétricas e paradas de potencial, na região dos ad-átomos de hidrogênio sobre eletrodos de Pt, em diferentes soluções ácidas, para produzir um aumento da corrente de pico da eletro-desorção do "terceiro" átomo de hidrogênio que aparece cerca de 0.22 V vs. RHE. Este pico pode ser observado para eletrodos de Pt de diferentes topografias. Aparentemente, a contribuição catódica correspondente aparece numa região de potenciais ligeiramente mais positivos que o potencial limiar da reação de desprendimento de hidrogênio. A diferença entre os potenciais de pico referentes as reações redox conjugadas é consistente com uma apreciável irreversibilidade do processo. A pequena carga envolvida neste par de picos é esperada para estados sub-superficiais e intersticiais dos ad-átomos de hidrogênio sobre Pt. Esse tipo de estrutura tem sido predita por cálculos da química quântica.

Combined potential routines involving voltammetric sweeps and potential holdings covering the H-adatom potential range were applied to Pt electrodes in different aqueous acid solutions to produce an enhancement of the "third" H-atom electrodesorption current peak at ca. 0.22 V vs. RHE. This peak can be observed for Pt electrodes of different topographies. Seemingly, the corresponding cathodic current contribution appears in a potential range slightly more positive than the hydrogen evolution reaction threshold potential. The peak potential difference related to the conjugated redox reactions is consistent with an appreciable irreversibility of the process. The small charge involved in this pair of peaks is expected from a subsurface and an interstitial H-adatom state on Pt. This type of structure has been predicted from quantum chemistry calculations.