a b s t r a c tNanocomposites obtained from the polymerization of aniline in the presence of nanoparticles of magnetite (Fe 3 O 4 ) have been investigated in previous studies. However, there is a lack of information available on the redox interaction of the nanoparticle/conductive polymer couple and the stability that such an oxide can give to the organic phase. In this work, Fe 3 O 4 nanoparticles were incorporated into a PANi matrix by the in-situ oxidative polymerization method. A combination of X-ray diffraction, Mössbauer spectroscopy, transmission electronic microscopy, UV-visible spectroscopy as well as the cyclic voltammetric and Raman spectroscopy techniques, was used to understand the redox effect that the partially oxidized nanoparticles produced on the polymer. It was found that magnetite greatly stabilised PANi, mainly by enhancing the Leucoemeraldine/Emeraldine redox couple and also by reducing the bipolaronic state.

The fuel cells are new alternatives for energy production with low environmental impact. Nowadays, conducting polymers are considered the most promising material to manufacture these type of cells because of their easy application and operation, being polypyrrole (PPy) one of them. The electrochemical synthesis of single-layer polypyrrole and two-layers or multiple-layers polypyrrole/platinum (PPy/Pt) films is reported in this paper. The films were obtained by electropolymerisation of pyrrole and cathodic deposition of platinum from ammonium hexachloroplatinate salt on stainless steel 304. The composition, morphology, conductivity and the electrochemical properties of the films were study by Raman Spectroscopy, SEM, Profilometer, impedance and cyclic voltammetry. The possible use of PPy and PPy/Pt films as electrodes for fuel cells is also discussed.Keywords: polypyrrole/platinum, conducting polymers, cyclic voltammetry. IntroducciónLos polímeros conductores son un tipo de materiales que tienen comportamiento redox, además de propiedades combinadas de metales y plásticos. Estos han sido estudiados por sus potenciales aplicaciones como: dispositivos para almacenar carga, materiales para baterías, celdas solares, electrodos modificados, recubrimientos anticorrosivos y transistores moleculares, entre otras [1,2]. Estos polímeros se perfilan como materiales prometedores para la fabricación de celdas de combustible en términos de su aplicación y operación, siendo el polipirrol (PPy) uno de ellos. El PPy presenta alta conductividad eléctrica, estabilidad térmica, resistencia a la oxidación, es de fácil obtención, puede formarse a partir de disoluciones acuosas y en disolventes orgánicos [3]. Además puede obtenerse por polimerización química o electroquímica considerando que la electropolimerización proporciona un mejor control del espesor y de la

In the case of emerging photovoltaic technologies such as perovskite, most published works have focused on laboratory-scale cells, indoor conditions and no international standards have been fully established and adopted. Accordingly, this chapter shows a brief introduction on the standards and evaluation methods for perovskite solar minimodules under natural sunlight conditions. Therefore, we propose evaluating the outdoor performance in terms of power, following the international standard IEC 61853–1 to obtain the performance according to the power rating conditions. After some rigorous experimental evaluations, results shown that the maximum power (Pmax) evolution for the analyzed minimodules could be correlated with one of the three patterns commonly described for degradation processes in the literature, named convex, linear, and concave. These patterns were used to estimate the degradation rate and lifetime (T80). Moreover, ideality factor (nID) was estimated from the open-circuit voltage (Voc) dependence on irradiance and ambient temperature (outdoor data) to provide physical insight into the recombination mechanism dominating the performance during the exposure. In this context, it was observed that the three different degradation patterns identified for Pmax can also be identified by nID. Finally, based on the linear relationship between T80 and the time to first reach nID = 2 (TnID2), is demonstrated that nID analysis could offer important complementary information with important implications for this technology outdoor development, due that the changes in nID could be correlated with the recombination mechanisms and degradation processes occurring in the device.

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