Banca de DEFESA: FELIPE DE MOURA SOUZA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : FELIPE DE MOURA SOUZA
DATA : 11/02/2021
HORA: 14:00
LOCAL: por participação remota
TÍTULO:

Development of palladium and niobium nanoelectrocatalysts for alkaline direct ethanol fuel cells

PÁGINAS: 213
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Físico-Química
ESPECIALIDADE: Eletroquímica
RESUMO:

Fuel cells are promising devices for generating electricity with minimal production of pollutants. This work aims to: synthesize, characterize, evaluate and apply binary Palladium with Niobium electrocatalysts for ethanol oxidation reactions (EOR) in alkaline medium, these materials being subsequently applied in a alkaline direct ethanol fuel cell. Briefly, in chapter 1, by the sol-gel method, where mainly PdO and Nb₂O₅ were obtained, the electrocatalyst Pd₁Nb₁ in mass and supported on Vulcan XC72 (Pd₁Nb₁/C) showed superior electrocatalytic activity for ROE and ADEFC (18 mW cm^-2 . In chapter 2, using the sol-gel method varying the type of carbon black for the Pd₁Nb₁ electrocatalyst, the Pd₁Nb₁ electrocatalyst supported on Printex 6L showed superiority to the other proportions and the commercial benchmark, reaching a maximum power density of 29 mW cm^-2. In chapter 3, using the NaBH4 method, the proportion was varied again, but now with nanoparticles of Pd and Nb metallic. The Pd₁Nb₁ electrocatalyst supported on Printex 6L showed superior electrocatalytic activity than the others, reaching 27 mW cm^-2 of power density. In chapter 4, graphene was synthesized from graphite by a green and simple ultrasonic method and used as a support for Pd nanoparticles. The performance result in ADEFC was 38 mW cm^-2 for graphene synthesized by ultrasonic method, being the highest power density achieved until this study period. Finally, in chapter 5, NaNbO₃ microcubes decorated with Pd nanoparticles were synthesized. The results showed great savings in the amount of Pd and high performance in ADEFC, achieving 18 mW cm^-2 using only 0.16 mg cm^-2  of Pd. The results indicate that Nb decreased the poisoning on the Pd surface due mainly to the bifunctional mechanism in which Nb provides oxygenated species for oxidation in the active poisoned Pd sites, other effects are also present. Therefore, Pd and Nb electrocatalysts have shown promise for use in an ADEFC anode.

MEMBROS DA BANCA:
Presidente - Interno ao Programa - 1544381 - MAURO COELHO DOS SANTOS
Membro Titular - Examinador(a) Interno ao Programa - 1601156 - WAGNER ALVES CARVALHO
Membro Titular - Examinador(a) Externo ao Programa - 2604737 - EVERALDO CARLOS VENANCIO
Membro Titular - Examinador(a) Externo à Instituição - GIUSEPPE ABÍOLA CÂMARA DA SILVA - UFMS
Membro Titular - Examinador(a) Externo à Instituição - FLÁVIO COLMATI JÚNIOR - UFG
Membro Suplente - Examinador(a) Externo ao Programa - 1671298 - RENATO ALTOBELLI ANTUNES
Membro Suplente - Examinador(a) Externo à Instituição - FABIO HENRIQUE BARROS DE LIMA - USP
Membro Suplente - Examinador(a) Externo à Instituição - ESTEVAM VITORIO SPINACÉ - IPEN