Banca de QUALIFICAÇÃO: ALLAN JEDSON MENEZES DE ARAÚJO

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : ALLAN JEDSON MENEZES DE ARAÚJO
DATE: 17/02/2020
TIME: 10:00
LOCAL: Sala de aulas do PPGCEM
TITLE:

DEVELOPMENT OF Ca-COBALTITE-BASED ELECTRODES FOR REVERSIBLE SOLID OXIDE CELLS

KEY WORDS:

Reversible solid oxide cells. Ca3Co4O9-based composites. Mollusk shell. Proteic sol-gel synthesis. Oxygen reduction reaction. Oxygen evolution reaction.

PAGES: 56
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
SPECIALTY: Cerâmicos
SUMMARY:

Materials for solid oxide fuel cell (SOFC) technology have been investigated in order to decrease the operating temperature from 1000 to 600-800 °C. Due to the tremendous importance of electrochemical energy conversion and, therefore, power generation, studies on novel cathode materials for SOFCs have received increasing attention in recent years. The thermoelectric material calcium cobaltite of composition [Ca2CoO3-δ]q[CoO2] (or more commonly Ca3Co4O9, C349) has been studied as a potential candidate for SOFC cathode. Ceramic-ceramic composites, structural doping, and synthesis methods are among the objectives of this field. Another device that has received attention is the solid oxide electrolysis cell (SOEC), which corresponds to the reverse operation of SOFC. The reverse mode is important for fuel production, such as H2 and syngas. With this in mind, the current work focus on the electrochemical characterization of PrOx- and Ce0.9Gd0.1O1.95(CGO)-C349 composites and their mechanisms for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in SOFC and SOEC mode, respectively. In order to improve the electrode performance in both modes, a comprehensive study of the relationships between composition and electrochemical properties of C349-based electrodes will be performed for the first time. Two different routes are used for preparation of powders. In the first route, a novel solid-state reaction using mollusk shell powder (a natural source of CaCO3) and Co3O4 will be carried out to obtain a pure C349 phase, and then another mixture with the phases PrOx and CGO. The second route is a proteic sol-gel synthesis which uses gelatin as a polymerizing agent. Some preliminary results were obtained by X-ray diffractometry (XRD), field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDS) of powders prepared by solid-state reaction. Rietveld refinement XRD results confirm the attainment of the misfit [Ca2CoO3-δ]0.62[CoO2] compound, with the refined lattice parameters for the different subsystems in accordance with the values in their respective ICSD files. FESEM and EDS images show plate-like particles for C349 samples at different calcination temperatures with homogeneous distributions of Ca and Co.

BANKING MEMBERS:
Externo à Instituição - FRANCISCO JOSÉ ALMEIDA LOUREIRO - UA
Presidente - 1300987 - CARLOS ALBERTO PASKOCIMAS
Externo à Instituição - DANIEL ARAÚJO DE MACEDO - UFPB
Interno - 1350249 - RUBENS MARIBONDO DO NASCIMENTO