Phenothiazines (PTZs) and their derivatives are a group of compounds that have diverse applications in medicine, the dye industry and advanced materials. Due to the electron–hole donating characteristic, these compounds have also been applied in batteries and solar energy devices. PTZs can be converted into stable radical cations by chemical and photochemical reactions. The PTZ radical cations are reactive for polymerization. The photochemical formation of PTZ radical cations is favored in aggregates by the Type I mechanism in which one molecule in the triplet excited state abstracts one electron from a neighbor molecule. In the present study, 10H‐phenothiazine (PHT) was dissolved in chloroform and converted to the radical cation species (PHT•+) by UV light irradiation. The radical cation was characterized by UV–visible absorption and electron paramagnetic resonance techniques. Addition of α‐Fe2O3 nanorods and nanowires to PHT•+ chloroform solution promoted its color change from orange to blue‐green. Absorption measurement revealed a significant decrease of the UV and visible bands assigned to radical cation species and the appearance of a broad band at the spectral region of 650 nm. The blue‐green solution was dried, leading to the formation of crystals that were characterized using the X‐ray diffraction technique. Considering possible PHT oligo(poly)merization, the crystals were analyzed using matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry that corroborated the formation of oligomers containing three, four and five PHT residues and their sulfoxide derivatives. The PHT oligomers retained photosensitivity and exhibited an electron paramagnetic resonance signal indicating possible applications as hole donors in electronic devices. Oligomerization was also obtained by aggregation of PHT•+ in sodium dodecylsulfate micelles indicating that proximity and orientation of the free radical molecules is the mechanism for the oligomerization. Therefore, a new route for PHT oligomerization catalyzed by α‐Fe2O3 nanowires is proposed. The method is readily available, inexpensive and environmentally safe. © 2022 Society of Industrial Chemistry.

RESUMO SOBRINHO, Luiza Ferreira. Oxidação eletroquímica do etanol em eletrólito alcalino utilizando nanocompósito a base de grafeno/ paládio. 2018 xx p. Dissertação (Mestrado em Tecnologia Nuclear) -Instituto de Pesquisas Energéticas e Nucleares -IPEN-CNEN/SP. São Paulo. Nesse estudo foi sintetizado e caracterizado o óxido de grafeno (OG) a partir do método de Hummers modificado. O OG foi utilizado como suporte para nanopartículas de paládio para uso como eletrocatalisador em células a combustíveis abastecidas diretamente a etanol. O uso de carbono grafite como suporte de nanopartículas metálicas é deteriorado com mais rapidez, levando a diminuição do tempo de vida útil da célula a combustível. O objetivo principal foi a incorporação do paládio no óxido de grafeno via feixe de elétrons, e a comparação com o catalisador incorporado por via química, utilizando o borohidrato de sódio. Foram utilizadas técnicas de caracterização tais como: termogravimetria (TG), difração de raios-X (DRX), as espectroscopias de Raman e infravermelho com transformada de Fourier (FT-IR), microscopia de transmissão eletrônica (MET), Espectroscopia de fotoelétrons por raios-X (XPS) e estudos voltamétricos como a voltametria cíclica e cronoamperometria. Os resultados indicaram que para a dose de 288 kGy, houve a incorporação, porém, não foi suficiente para que houvesse a redução dos grupos oxigenados, estudos com o oxido de grafeno previamente reduzido via térmica e incorporado via feixe de elétrons foram comparados na mesma dose. Palavras-chave: óxido de grafeno; paládio; voltametria cíclica; célula à combustível. ABSTRACT SOBRINHO, Luiza Ferreira. Electrochemical oxidation of ethanol in alkaline electrolyte using graphene / palladium base nanocomposite. 2018 xx p. Dissertação (Mestrado em Tecnologia Nuclear) -Instituto de Pesquisas Energéticas e Nucleares -IPEN-CNEN/SP. São Paulo.In this study, graphene oxide (GO) was synthesized by the modified Hummers method and characterized. GO was used as support for palladium nanoparticles as an electrocatalyst on direct ethanol fuel cell (DEFC). One of the drawbacks using carbon graphite as a support for metal nanoparticles was because it deteriorates more quickly, leading to shortened fuel cell life. The main objective was the incorporation of Pd on the graphene oxide by the electron beam and was compared with the chemical incorporation, using sodium borohydride. Characterization techniques such as thermogravimetry (TG), X-ray diffraction (XRD), Raman spectroscopy and Fourier transform infrared (FT-IR), electron transmission microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and voltammetric studies such as cyclic voltammetry and chronoamperometry. The results indicated that at a dose of 288 kGy, there was an incorporation, however, it was not enough for there to be a decrease in the groups of oxygenates, studies with the graphene oxide downloaded through the thermal and through electron beams were compared in the same dose.

Graphene oxide (GO) can be partially reduced to graphene-like sheets by removing the oxygen-containing groups and recovering the conjugated structure. In this work, the thermal reduction of GO powder has been carried out using back pumping vacuum pressures and investigated employing X-ray diffraction analysis. The experimental results of estimating the number of graphene layers on the reduced powder at various temperatures (200 – 1000 °C) have been reported. Electrical changes have been produced in a graphene oxide with the vacuum reduction process. This study has shown that the ideal processing temperature for reducing graphene oxide nanomaterial was about 400 °C. It has also been shown that at 600 °C the number of layers in the reduced nanomaterial increased. The internal series equivalent resistance (ESR) has been improved substantially with the vacuum thermal treatment even at temperatures above 400 °C. ESR was reduced from 95.0 to about 13.8 Ω cm2 with this processing. These results showed that the process can be applied to the reduction of graphene oxide to produce supercapacitor nanomaterials. The advantage of employing this method is that the processing is a straightforward and low cost thermal treatment that might be used for large amount of nanocomposite material.