Banca de DEFESA: CIRO JOSE FERREIRA RODRIGUES

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : CIRO JOSE FERREIRA RODRIGUES
DATA : 19/08/2017
HORA: 09:00
LOCAL: Sala de aulas do PPGCEM
TÍTULO:

 

PALAVRAS-CHAVES:

SOFC, composite anodes, hydrothermal synthesis, aluminum, tin.

PÁGINAS: 92
GRANDE ÁREA: Engenharias
ÁREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
ESPECIALIDADE: Cerâmicos
RESUMO:

Solid Oxide Fuel Cells (SOFCs) are among modern devices that generate energy from hydrogen sources. SOFCs consist basically of three ceramic constituents acting as electrodes and electrolyte. Yttria-stabilized zirconia/NiO are traditional materials used as mixed anodes that operate with different sources of hydrogen. Although YSZ-NiO depicts high electrical energy conversion, it can only operate between 800 and 1000ºC. Alternative materials based on doped ceria show similarionic conductivity, lower ohmicloss and become operational between 500 and 800ºC. In a mixed anode composition, NiO acts as catalyst in the fuel reform, granting high electrical conductivity. On the downside, the costs of the material are relatively high, and the catalytic activity is decreased by the production of coke. The present study aimed at evaluating the synthesis of mixed ceria-doped anodes using different catalysts, i.e., Al₂O₃ and SnO. NiO was also used as reference for the efficiency of electric conductivity. The following compositions were synthesized by the microwave assisted hydrothermal synthesis: Ce_0.8Sm_0.2O_1.95-Al₂O₃ (SAL).Ce_0.8Gd_0.2O_1.95-Al₂O₃(GAL).Ce_0.8Sm_0.2O_1.95-SnO₂ (SSN).Ce_0.8Gd_0.2O_1.95-SnO₂ (GSN).Ce_0.8Sm_0.2O_1.95-NiO (SNI) and Ce_0.8Gd_0.2O_1.95-NiO (GNI).The powders were characterized by SEM, thermal analysis and XRD. The electrical conductivity was evaluated by cyclic voltammetry. The method of synthesis was efficent in the preparation of all compositions studied. The crystallinity of the powders was compatible with that of other synthesis methods. SAL and GAL depicted high values of electrical conductivity, as a consequence of the relatively low densities of anodic and cathodic current. Measured peak currents were 1.01 x 10^-5 A/mm² for SSN,6.17 x 10^-5 A/mm² for GSN, 1.60 x 10^-5 A/mm² for SNI and 1.81 x 10^-4 A/mm² for GNI. These values suggest the occurrence of electrocatalytic reactions and low electrical conductivity for this kind of electrochemical analysis. 

MEMBROS DA BANCA:
Presidente - 1298936 - ANTONIO EDUARDO MARTINELLI
Externo à Instituição - DANIEL ARAÚJO DE MACEDO - UFRN
Externo à Instituição - DANIEL ZANETTI DE FLORIO - UFABC
Interno - 349770 - DULCE MARIA DE ARAUJO MELO
Interno - 1350249 - RUBENS MARIBONDO DO NASCIMENTO