Banca de DEFESA: ANA MELISSA PAULA BRITO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : ANA MELISSA PAULA BRITO
DATE: 22/09/2023
TIME: 13:30
LOCAL: https://meet.google.com/ims-rkcm-pbf
TITLE:

Characterization of the photocatalytic and photoluminescence properties of Bi₂WO₆:xPr³⁺ with added beetroot extract obtained by microwave-assisted hydrothermal.

 

KEY WORDS:

Bismuth tungstate; praseodymium; beetroot extract; microwave-assisted hidrothermal method; photocatalysis and photoluminescence.

PAGES: 88
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
SPECIALTY: Cerâmicos
SUMMARY:

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
(Bi 2 WO 6 ) stands out as a photocatalyst for environmental remediation. In this work,
Bi 2 WO 6 :xPr 3+ (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 Pr 3+ 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 Pr 3+ 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 Bi 2 WO 6 :xPr 3+ 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, Bi 2 WO 6 :xPr 3+ 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.

COMMITTEE MEMBERS:
Presidente - 1883170 - MAURICIO ROBERTO BOMIO DELMONTE
Interna - 1802888 - FABIANA VILLELA DA MOTTA
Externa à Instituição - MARIA INES BASSO BERNARDI - USP