Electronic transport properties in the Ni/ZrO2 composite anode: First-principles calculations

• Main Authors: Yun-IHo, 何筠怡
• Other Authors: Yen-Hsun Su
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/ue6r67

碩士 === 國立成功大學 === 材料科學及工程學系 === 106 === With the greenhouse effect existing for many years, many countries have tried to promote renewable energies. Solid oxide fuel cells (SOFC) can be regarded as one of the talented energy. Not only does it have a higher energy density than other types of fuel cells, but also it has advantages of high conversion efficiency and non-pollution. Although Ni/ZrO2 is a classical anode material of SOFC, there has been little discussion on the effect of structure orientations. In this study, we investigate the geometric and electronic properties of Ni/ZrO2 heterostructures from first-principle calculations, focusing on the effect of different orientation angles at the interface. We compare density of states and the transmission spectra of six heterostructures. After optimization, the Ni-O bond and the interfacial spacing decrease, indicating that there might be an interaction at the interface. Also, in density of states, the charge transferred between Ni d orbitals, O p orbitals and Zr d orbitals can be observed. Comparing the transmission coefficients and the local density of states (LDOS) of the heterostructures at the Fermi energy with different orientations, the structure of 30o shows a higher transmission coefficient, and there is LDOS overlaps between Ni and Zr atoms, attributed to the hybridization of Ni-Zr. If we consider application, hydrogen and methane are the common fuels in the usage of SOFC. The open circuit voltages (OCV) are 1.05 V and 1.15 V, respectively. Corresponding to the transmission spectrum and LDOS, the 90o structure shows a higher transmission coefficient. Also there is a hybridization between the interface, which provides the structure a good transport characteristic. In summary, 90o structure shows a better transmission peroperty in application. Overall, the orientation of the interface indeed has effects on the electronic transport properties of the Ni/ZrO2 systems.