(A) sintering-/coking-resistant metal-oxide nanocomposite catalyst for solid oxide fuel cell anodes

Abstract

Despite unique catalytic activity and high surface-to-volume ratio, metal nanoparticles (NPs) have not actively been used for high-temperature applications because they are usually apt to agglomerate into larger crystallites upon annealing, thus leading to degradation in catalytic performance. Among the many research efforts to enhance the thermal stability of NPs, we decorate metal NPs with Al2O3 nanolayers via ALD, thus enabling to obtain thermal durability of particles. Although there have been many studies to stabilize NPs with ALD, there are a few reports about the utilization of ALD on electro-catalysts in high temperature applications such as solid oxide fuel cells (SOFCs) or solid oxide electrolysis cells (SOECs). In this thesis, to obtain high cell performance of SOFC anode, I have taken the initial tasks such as synthesis of particles and the evaluation of the electrochemical activity of the ALD coated NPs. Not only the successful fabrication of NPs but also the investigation of their growth mechanism have been discussed. Finally, feasibility of enhancing cell performance using stabilized NPs by ALD were confirmed. Morphology and properties of NPs were investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), UV spectra and zeta potential measurement. Physical attributes of ALD layers are characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD). Performance investigation of symmetric cells (anode/electrolyte/anode) with and without ALD coatings conducted by electrochemical impedance spectroscopy (EIS) are presented. These observations provide feasibility of ALD coating for the achievement of physically and chemically stabilization of nanoparticles for electrochemical catalysts