In this work, a detailed chemical route to prepare thermally stable polyaniline (PANI)/carbon black (CB) composites is described. The syntheses were performed by chemical polymerization of aniline over CB particles, using different PANI/CB mass ratios. The thermal and electrical properties were characterized. Composites with mass ratio up to 65:35 (PANI:CB) showed excellent thermal stability maintaining their conducting properties when thermally treated at 230 °C for two hours, which is adequate to process these materials. Moreover, the results showed an important reduction in the surface area of the composites which have a good relationship with the improvement of the rheological properties in melt processing.

The present study aims the development and application of an electrochemical method for simple coumarin determination in aqueous media by using a boron-doped diamond electrode (BDDE). The studies were carried out at pH 8.0 by cyclic voltammetry (CV) and registered an irreversible reduction process controlled by diffusion with the peak potential recorded around -1.6 V. The square wave voltammetry analysis (SWV) showed the reversible behavior of the electrochemical reduction of coumarin at the same pH. Additionally, the reversibility of the process was improved by increasing the solution pH. The chronoamperometry study showed that the coumarin reduction process involves two electrons. From the optimized SWV parameters, the analytical curve was constructed in a linear range between 0.5 × 10-5 and 10.0 × 10-5 mol L-1. The limits of detection and quantification were 1.5 × 10-6 mol L-1 and 4.5 × 10-6 mol L-1, respectively. The coumarin was determined in an aqueous infusion of Mikania glomerata, showing recovery values between 92 and 104%.

Electrochemical behavior of pesticides is extensively studied, but little attention has been given to the study of their degradation products (by-products) by electrochemical methods. However, the degradation products of pesticides can be even more toxic then the parent products and such studies should be encouraged. Therefore, the objective of this work was to evaluate the electroactivity of by-products of imazaquin, methylparathion, bentazon and atrazine, generated by UV irradiation and measured using cyclic and differential pulse voltammetry and UV-visible absorption spectrophotometry. Results have shown that several by-products exhibit electroactivity, allowing, in some cases, the simultaneous determination of both parent and degradation products.

Multilayer graphene (G-US) and multilayer graphene muffled (Gm-US) produced by liquid exfoliation ultrasound were used as support for Pd nanoparticles with a load of 20 wt% for application in an alkaline direct ethanol fuel cell (ADEFC) anode. The multilayer graphene–based electrocatalyst (Pd/G-US) exhibited superior current density and less positive onset potential for ethanol oxidation reaction (EOR) than the commercial Pd/C (AA). Also, the Pd/G-US electrocatalyst showed the less positive onset potential for CO oxidation. In ADEFC experiments, the Pd/G-US catalyst exhibited a superior performance with 38 mW cm−2. The findings suggest that the defective graphene structure promotes electron transport, and the presence of oxygenated species increases hydrophilicity facilitating the oxidation of intermediates. Hence, the synthesized material can be considered as promising support for an anode in ADEFC. Graphical abstract: [Figure not available: see fulltext.]