OXYGEN TRANSPORT KINETICS OF SURFACE Pt &Ag-MODIFIED PEROVSKITE OXIDE La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF)

Zhu, Shaochen (2017) OXYGEN TRANSPORT KINETICS OF SURFACE Pt &Ag-MODIFIED PEROVSKITE OXIDE La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF).

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Abstract:0.4Co0.2Fe0.8O3-δ (LSCF) perovskite oxide is considered as a promising candidate for intermediate temperature solid oxide fuel cell (IT-SOFC) cathode material, due to its excellent mixed ionic and electronic conductivity, high oxygen reduction activity and high stability. Recent research shows that with catalytic metals coated on the surface, the surface exchange performance of LSCF can be further enhanced[1], while the mechanism needs to be further investigated. In this study, dense perovskite La0.6Sr0.4Co0.2Fe0.8O3-δ membranes were fabricated using commercial powders. The prepared membranes were polished and thermo-treated to achieve a smooth surface. Platinum and silver nanoparticles were homogenously deposited on the membrane surface by sputtering to modify the membrane surface. The influence of metal deposition on the surface oxygen reduction reaction (ORR) was investigated. The kinetic parameters of oxygen transport, the oxygen diffusion coefficient (Dchem) and the surface exchange coefficient (kchem) were characterized by electrical conductivity relaxation (ECR). The ECR measurements were conducted in the range of 600 °C to 900 °C with an oxygen partial pressure (PO2) step change from 0.215 atm to 0.464 atm and vice versa. The results reveal that the oxygen diffusion in LSCF is independent to the platinum deposition but greatly affected by the silver deposition. For bare LSCF, the surface exchange coefficient is of a factor of 10 higher than the literature values at 800 °C, and is not further promoted by either of these catalytic particles.
Item Type:Essay (Master)
Faculty:TNW: Science and Technology
Subject:51 materials science
Programme:Chemical Engineering MSc (60437)
Link to this item:http://purl.utwente.nl/essays/73369
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