Caracterização das propriedades fotocatalíticas e fotoluminescentes de Bi2WO6:xPr3+ com adição de extrato de beterraba obtidos pelo método hidrotérmico assistido por microondas

Abstract

Green synthesis has shown to be a promising for obtaining nanoparticles because it is an economical and ecologically correct alternative. Due to its interesting structural and electrochemical properties and the use of different ways of obtaining it, bismuth tungstate (Bi2WO6) stands out as a photocatalyst for environmental remediation. In this work, Bi2WO6:xPr3+ (x = 0; 1 and 3 %molar) nanoparticles, with addition of beetroot extract (BE), were synthesized by the microwave-assisted hydrothermal method at 150°C for 60 min. Thus, the samples were structurally characterized by the X ray diffraction (XRD) and their morphology was investigated by the field emission scanning electron microscopy (FESEM). Photocatalytic activity of the samples was quantified by the UV-visible (UV-Vis) spectroscopy technique through the degradation of methylene blue (MB) and crystal violet (CV) dyes by ultraviolet and solar irradiation. Optical properties were investigated using the photoluminescence (PL) technique. The XRD patterns showed that the samples have an orthorhombic crystalline structure and good crystallinity, without the presence of secondary phases, which indicates that the presence of the Pr3+ dopant and the addition of beetroot extract do not generate additional phases. In addition, the crystallite size ranged from 6.48 nm to 10.27 nm, a slight increase was noted when the Pr3+ dopant was inserted, but as the amount of BE increased, the crystallite size decreased. The FESEM micrographs showed that the obtained nanoparticles have a predominantly flower-like morphology. The bandgap energy of the Bi2WO6:xPr3+ ranged from 3.56 eV to 3.65 eV. Photocatalytic tests indicated that all the samples have potential for MB and CV degradation. In addition, PL spectra found that the nanoparticles had a color rendering index (CRI) greater than 80%, which makes this nanomaterial a potential for applications in high quality white light emitting diodes (LED’s). Furthermore, it was observed that the active photocatalytic mechanism consists of superoxide and holes. Therefore, Bi2WO6:xPr3+ nanoparticles, using green synthesis and sunlight, is a promising, efficient and economical alternative for the degradation of organic dyes as well as for LED’s applications.