Banca de DEFESA: MARCOS ROBERTO DA SILVA VICENTE

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : MARCOS ROBERTO DA SILVA VICENTE
DATE: 11/09/2023
TIME: 14:00
LOCAL: https://meet.google.com/agr-fefb-fqy
TITLE:

SYNTHESIS OF SODIUM NIOBATE PEROVSKITES WITH APPLICATION IN CO₂ CONVERSION AND WATER PHOTOSPLITTING

PAGES: 82
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Inorgânica
SPECIALTY: Físico Química Inorgânica
SUMMARY:

Hydrogen gas is considered one of the most promising substances to be used as an alternative to fossil fuels. CO₂, on the other hand, is a gas that promotes the increase of the greenhouse effect and consequently global warming. In this context, photoelectrochemical water spliting, and CO₂ conversion using metal semiconductor oxides as catalysts and sunlight as energy, is an attractive strategy. Among the materials investigated for these purposes NaNbO₃ has shown great promise. However, to increase the catalytic efficiency it is necessary to control the morphology, crystalline structure, optimize the lifetime of the photogenerated charges and modulate the visible light absorption capacity. This work aims to study the optimization of the synthesis of sodium niobate, NaNbO₃, through microwave-assisted hydrothermal routes. These systems were doped with nitrogen from in situ polymerization of graphitic carbon nitride (g-C₃N₄). In addition, platinum was used as a co-catalyst in order to reduce the recombination effects of the photogenerated charges. Scanning electron microscopy images show that different morphologies are obtained from variations in the synthesis conditions. On the other hand, X-ray diffraction analysis and Raman spectroscopy showed that the orthorhombic structure was obtained regardless of the reaction conditions.   It was observed that the incorporation of platinum has a more substantial effect on the reduction of the bandgap energy, while the effect of doping with g-C₃N₄ is still to be studied. Finally, electrochemical characterization of the materials was performed. It was possible to observe that the sensitivity of NaNbO₃ to visible radiation depends on the reaction conditions. Finally, decoration with the lowest platinum plasmonic nanoparticles positively influences the response to light for all materials. For the doped materials, the higher platinum content showed better photoelectrochemical activity results, while for the pure materials, the lower ones. 

COMMITTEE MEMBERS:
Presidente - Interno ao Programa - 2351974 - JULIANA DOS SANTOS DE SOUZA
Membro Titular - Examinador(a) Interno ao Programa - 3298744 - JOSE MIRANDA DE CARVALHO JUNIOR
Membro Titular - Examinador(a) Externo à Instituição - JÚLIO CÉSAR MARTINS DA SILVA - UFF
Membro Suplente - Examinador(a) Interno ao Programa - 3323134 - LUIZ DUARTE RAMOS
Membro Suplente - Examinador(a) Externo à Instituição - IRINA MARINHO FACTORI