Síntese de nanofios de Niobato de sódio (NaNbO3) pelo método hidrotérmico assistido por micro-ondas e sua atividade fotocatalítica

Abstract

Sodium niobate (NaNbO3), which has a crystalline structure of the Perovskite type, is gaining more and more attention, as it has characteristics that allow great technological applicability. So far, its particles have been obtained by various routes of synthesis, but it has been reported frequently in cubic form and rarely in the form of nanowires. Therefore, the present work aimed to present a simple, fast and low temperature method for obtaining NaNbO3 nanowires, using the microwave assisted hydrothermal method and analyzing its photocatalytic activity. The samples, of NaNbO3, were subjected to heat treatment, at different temperatures, to analyze the influence on the phase, shape, optical band gap and photocatalytic performance. The photocatalytic activity of the samples was investigated through the photodegradation of Rhodamine B (RhB), a dye widely used in industry and known for its high toxicity, good stability and non-biodegradability. Techniques of thermogravimetric analysis, thermal differential, X-ray diffraction, scanning electron microscopy and UV-Vis spectroscopy were performed to characterize the samples. The Perovskite obtained has an orthorhombic structure, space group Pbma and it has been demonstrated that, as the temperature of the heat treatment increases, this phase is maintained, there is an increase in the values of the optical gap, with a minimum value of ~ 3.35 eV at 350°C and a maximum of ~3.60 eV at 800°C and there is an increase in the degree of crystallinity, reflecting in a better photocatalytic performance, resulting in high rates of RhB photodegradation, with a degradation percentage of ~63.49% at 350ºC and ~ 99.21% at 800ºC. Keywords: sodium niobate; nanowires; microwave-assisted hydrothermal method; heat treatment; perovskite; photocatalysis.