Banca de DEFESA: MARCELO FRANCISCO TAGLIALENHA LIMA ISSY DE SOUSA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : MARCELO FRANCISCO TAGLIALENHA LIMA ISSY DE SOUSA
Date: 18/11/2026
TIME: 14:00
LOCAL: Santo André
TITLE:

Halide Double Perovskites for Solar-driven Applications: The Role of Dimensionality and Structural Stability

PAGES: 70
BIG AREA: Ciências Exatas e da Terra
AREA: Física
SUBÁREA: Física da Matéria Condensada
SPECIALTY: Prop. Óticas e Espectrosc. da Mat. Condens; Outras Inter. da Mat. com Rad. e Part.
SUMMARY:

Lead-free halide double perovskites have emerged as promising semiconductor materials for sustainable energy conversion and environmental remediation (solar-driven applications) due to their reduced toxicity, improved chemical stability, and structural versatility. In this work, three-dimensional and two-dimensional silver–bismuth bromide double perovskites are investigated, with emphasis on the comparison between bulk Cs2AgBiBr6 and layered Ruddlesden–Popper phases based on butylammonium spacers. The main goal is to understand how dimensionality affects crystal structure, morphology, optical properties, charge transport, photocatalysis, and photoelectrochemical performance. The materials were synthesized by solution-based crystallization in hydrobromic acid media, using controlled precursor stoichiometry and organic spacer incorporation to tune the dimensionality. Morphological and structural characterizations reveal a clear evolution from lamellar, plate-like microcrystals in the 2D phases to faceted octahedral crystals in the 3D compound. X-ray diffraction and Rietveld refinement confirm the formation of distinct layered and bulk phases, while optical measurements show that dimensional reduction modifies the band structure, excitonic behavior, and light absorption response. The photodegradation of Rhodamine B (RhB) and photoelectrochemical results indicate that aqueous media and dimensionality play a decisive role in balancing light harvesting, charge separation, surface reactivity, and chemical stability. Although the bulk 3D phase showed the highest photoactivity, it was also highly susceptible to rapid structural degradation and phase segregation into BiOBr and AgBr in purely aqueous media. In contrast, the 2D phases exhibited lower photoactivity than the 3D counterpart but showed slower structural degradation and reduced phase segregation. While 2D phases may improve surface exposure and environmental resistance, the 3D phase offers more favorable charge transport pathways. The study also emphasizes the importance of the degradation media, electrolyte, and pH conditions, since the reaction environment strongly affects both activity and stability. Overall, this work establishes dimensionality engineering and media/electrolyte as effective strategies to tune lead-free halide double perovskites for solar-driven hydrogen production and pollutant degradation.

COMMITTEE MEMBERS:
Presidente - Interno ao Programa - 2605463 - JOSE ANTONIO SOUZA
Membro Titular - Examinador(a) Interno ao Programa - 1671275 - DERVAL DOS SANTOS ROSA
Membro Titular - Examinador(a) Externo à Instituição - FELIX GUILLERMO GONZALEZ HERNANDEZ - USP
Membro Suplente - Examinador(a) Interno ao Programa - 1734908 - FABIO FURLAN FERREIRA
Membro Suplente - Examinador(a) Interno ao Programa - 1707133 - ISELI LOURENCO NANTES
Membro Suplente - Examinador(a) Externo à Instituição - SUELEN DE CASTRO - UNIFEI - UNI