Electrochemical Impedance Spectroscopy Analysis of 2-Mercaptobenzimidazole (2MBI) as Corrosion Inhibitor in HCl 1M

This work presents the results concerning the effect of different concentrations of an organic heterocyclic compound that displays corrosion inhibiting properties, known as 2-mercaptobenzimidazole, 2MBI, in a system comprising samples of the steel type API 5L X52 exposed to HCl 1M. The impedance spectra revealed that there was a continuous increase of |Z| as a function of increasing inhibitor concentrations in the electrolyte. A 200 ppm 2MBI was tested also, however, the greatest corrosion inhibiting efficiency was attained 99%, IE, with much smaller concentrations of the compound. This is sufficient reason to consider it a good corrosion inhibitor in HCl, just as it was effective for H 2 SO 4 . Furthermore, the inhibition kinetics study undertaken indicated that the 2MBI added in a fairly large concentration of 200 ppm in 1M HCl maintains its effectivity up to 32 immersion days. Also, it was observed that the corrosion potential, E corr , became more negative as the 2MBI organic molecules concentration increased in the system, which suggests that this inhibitor may be acting on the cathodic and anodic sites, thus being considered a mixed type inhibitor, in agreement with the corrosion mixed potential theory

2D Materials-based platforms for electroanalysis applications

A new class of nanomaterials called "2D materials" (2DMs) is attracting recently the electrochemical sensing field due to the unique physicochemical properties associated to their chemical structure, formed by ultra-thin layers. In this review, we summarize the recent advances in the electroanalysis area using 2DMs giving first a brief overview on the structure, synthesis and properties of these materials followed by the analysis of their advantages while used in the development of electrochemical sensors

Characterization of black and white chromium electrodeposition films: surface and optical properties

Thin films of black and white chromium have been prepared by electrodeposition on stainless steel substrates. The potentiodynamic and potentiostatic technique was used in order to prepare these materials. XRD, XPS, SEM and spectral reflectance in the UV–Visible–near IR and medium IR ranges, for both films coatings were characterized. From the SEM analysis, it was found while the black chromium has a lamellar morphology that leads to a strong dispersion level, the white one has a flat morphology. The chemical composition of these thin films was determined by XRD and XPS technique. The XRD results showed that in both cases chromium is the main bulk chemical compound in both films. However, from XPS analysis of these surfaces, it was possible to determine that the most external layers of the films are made of different kinds of chromium compounds. The black chromium film has better optical properties to transform solar energy into thermal energy, and these properties remain practically constant even when heat treated to a high temperature, 400 °C. On the other hand the white chromium film is a better substrate for hydrogen evolution reactions than the black one

Construction of Supramolecular Systems for the Selective and Quantitative Determination of Dopamine in the Presence of Ascorbic Acid

AbstractThis work presents the construction of supramolecular systems formed by the modification of carbon paste electrodes, CPE, with multiwalled-carbon nanotubes, MWCNT, and b-cyclodextrin, CPE/MWCNT/β-CD, a novel conducting polymer produced by electrochemical polymerization of β-CD, CPE/poly-β-CD and another formed with MWCNT, β-CD and poly-β-CD, CPE/MWCNT/β-CD/poly-β-CD. With these modified electrodes, analyses were performed to understand the effect of such surface modifications on the electrochemical response of the analyte dopamine, which was surface-immobilized through formation of the said inclusion complex, as evidenced by the adsorption process that controlled the overall reaction rate of the oxidation process. Moreover, it is shown that the heterogeneous rate constant, k0, of Dopamine oxidation is highly increased in the presence of poly-β-CD

Bimetallic PdCo and PdFe electrocatalysts for the electrochemical oxidation of formica acid

Pd, PdCo and PdFe catalysts were prepared by the impregnation method, using sodium borohydride (NaBH4) as the reducing agent and a commercial carbon material (Vulcan XC-72R) as support. The synthesized electrocatalysts were tested for the formic acid oxidation reaction (FAOR) in acid medium (H2SO4 0.5 M). The morphology, composition and particle size of the electrocatalysts were characterized by physicochemical techniques as X-ray diffraction (XRD), scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and transmission electron microscopy (TEM). The catalytic activity was evaluated by cyclic voltammetry (CV) and chronoamperometry techniques (CA)Catalizadores de Pd, PdFe y PdCo fueron preparados por el método de impregnación, usando borohidruro de sodio (NaBH4) como agente reductor y un material de carbono comercial, (Vulcan XC-72R) como soporte. Los electrocatalizadores sintetizados fueron probados para la reacción de oxidación de ácido fórmico (FAOR, por sus siglas en inglés) en medio ácido (H2SO4 0,5 M). La morfología, la composición y el tamaño de partícula de los electrocatalizadores se caracterizaron mediante técnicas físico-químicas como difracción de rayos X (XRD), microscopía electrónica de barrido con espectroscopia por energía dispersiva (SEM-EDS) y microscopia electrónica de transmisión (TEM). La actividad catalítica se evaluó mediante técnicas de voltamperometría cíclica (CV) y cronoamperometría (CA