Hybrid inorganic-organic solar cells are an attractive alternative energy source because of their low-cost production and ability to make use of a large amount of solar radiation available. This work aims to evaluate different solar cells composed of TiO2 and ZnO with P3OT/P3MT copolymer. Layers of semiconductor oxides were deposited on transparent fluorine-doped tin oxide (FTO) by spin coating and adsorption in the polymer solution. X-ray diffraction (XRD), scanning electron microscopy (SEM), were used to characterize the fabricated semiconductors and curves of current density vs. potential (j-V), photochronoamperometry (j-t) and electrochemical impedance spectroscopy (EIS) were used to determine their electrical characteristics. The XRD analyses confirmed the crystalline nature of the oxide materials. SEM micrographs showed the spherical morphology of ZnO and the poorly defined agglomerate morphology of TiO2. The electrochemical measurements proved that the best cell was produced with P3OT/P3MT copolymer and TiO2, owing to its lower charge transfer resistance, with the following photovoltaic parameters: Voc = 0.615 V ± 0.004, jsc = 1.545 mA cm-2 ± 0.240, FF = 0.637 ± 0.003, and η = 0.617% ± 0.117.

The use of corrosion inhibitors is one of the most common methods to combat acid corrosion. The current studies aim to apply natural products as corrosion inhibitors, once the most used compounds are mostly toxic to the environment and to humans. The present paper purposes the application of an aqueous extract of agro-industrial waste (AEAW) to inhibit the corrosion of stainless steel AISI 304 in sulfuric acid. Gravimetric and electrochemical experiments were performed. The gravimetric experiments revealed that the extract acts as an inhibitor for stainless steel, showing inhibitory efficiency up to 81.6%. The electrochemical tests show that the AEAW makes the steel surface more noble. The extract acts by adsorption in the metallic surface, following a Temkin isotherm. The results indicate that the AEAW is a promising substitute of conventional organic compounds as a corrosion inhibitor to AISI 304 stainless steel in sulfuric acid.

Hybrid solar cells show an increasing number in researches due to its low cost and easy of production. They are composed by and organic material and a semiconductor oxide. The aim of this paper was to synthesis and characterize zinc oxide by coprecipitation and apply it in a hybrid solar cell that uses a P3HT/P3OT copolymer as charge carrier. The cell was assembled in "sandwich" form using FTO/ZnO/P3HT-P3OT as work electrode, (Pt/FTO) as conter electrode and I/I-3 redox couple as electrolyte. Through the X-ray diffractogram the formation of a single ZnO wutzite hexagonal phase was observed. The morphology obtained for the oxide was spherical. The results of photochronoamperometry showed current density values of jP3HT/P3OT =0.55 mA.cm-2 for the cell in the presence of the copolymer and the curve jxV showed an efficiency of 0.16% for the studied cell, demonstrating that the polymer was a satisfactory sensitizer.

Dye-sensitized solar cells (DSSC) have received much attention as an alternative to silicon-based solar cells, due to various advantages. Zinc oxide (ZnO) is an n-type semiconductor employed as photoanode on DSSC. The decrease of charge recombination is an efficient strategy capable of improving the photovoltaic performance of the device. In this perspective, Nb2O5 was added on ZnO solar cells. The oxides were characterized by the X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and X-ray fluorescence (XRF). The photovoltaic parameters were obtained through J-V plots and photocronoamperometry. The results showed that the niobium oxide obtained presented orthorhombic crystal structure and DSSC with the addition of niobium oxide showed better efficiency, of 1.42% when compared the device with only ZnO.

In this study, the corrosion protection provided by films of self-assembled molecules on the AA 2024-T3 aluminum alloy has been evaluated by electrochemical and non electrochemical techniques. The film was obtained by immersion of this alloy samples in a solution of 90 mg L-1 alkane-diphosphonate at 50 °C for 5 minutes. Chromating conversion treatment with trivalent or hexavalent chromium was carried out by immersion of AA 2024-T3 alloy samples for 2 minutes in a 20% (v/v) solution of 650 Chromical TCP (SurTec) at 40 °C. Electrochemical characterization was performed by measurements of the open circuit potential (OCP), potentiodynamic polarization curves (PPC) and electrochemical impedance spectroscopy (EIS) in a solution of 0.5 mol L-1 sodium sulfate buffered with a solution of biphthalate potassium (0.1 mol L-1) and sodium hydroxide (0.1 mol L-1) as the electrolyte. SAM films obtained were analysed by infrared spectroscopy and SAM was found in surface. Surface observation by scanning electron microscopy (SEM) showed that the trivalent chromium layers ere deposited on metal surface. The results show that the surface treatment with self-assembled molecules provides protection against corrosion of the AA 2024-T3 aluminum alloy.

A adsorção das substâncias orgânicas nos metais, em diferentes meios, tem sido atribuída a diferentes efeitos, tais como: tamanho da cadeia carbônica, tipo ou número de heteroátomo presente na estrutura da molécula, reatividade, efeito estérico, entre outros. O objetivo desse trabalho é estudar o comportamento eletroquímico do Indol (C8H7N), para o aço inoxidável AISI 430, quando se muda o meio de estudo de H2SO4 1 mol L-1 para HCl 1 mol L-1. Experimentalmente foram empregadas as técnicas seguintes: medida de potencial de circuito aberto, curvas de polarização potenciodinâmica anódica e catódica, espectroscopia de impedância eletroquímica, microscopia óptica e eletrônica de varredura. Esses resultados sugerem que a adsorção do indol, em presença de SO4-2, é menor em relação ao meio que contem íons Cl-, fato justificado pela ação do indol como ácido fraco, pois o mesmo possui apenas um único par de elétrons, o qual é deslocado e participa do sistema π-elétron aromático. Dessa forma, a primeira etapa da reação do indol, em meio ácido, é a protonação e a geração de um indol cátion.

The adsorption of organic substances in metals and in different media has been attributed to different effects, such as the carbon chain size, type or number of heteroatom in the molecule structure, reactivity, the steric effect, among others. The objective of this work is to study the electrochemical indole behavior for AISI 430 stainless steel (SS), when changing the study media from H2SO4 1 mol L-1 to HCl 1 mol L-1. The experimental techniques used are as follows: the open-circuit potential, anodic and cathodic potentiodinamic polarization, electrochemical impedance spectroscopy, optical microscopy and scanning electron microscopy. These results suggest that the adsorption of indole in the presence of SO4-2 is lower than in the medium containing Cl-, which is justified by the indole action as a weak acid, because it has only a single pair of electrons, which is displaced and takes part in the π-electron aromatic system; thus the first step of the indole reaction in acid media is the protonation and generation of an indole cation.