Theoretical Study on Artificial Polar Surface of Metal Oxide Superlattice

Abstract

Metal oxide material for oxygen reduction reaction (ORR) has been receiving much attention in renewable energy technologies such as fuel cell. Although the catalytic efficiency can be improved by engineering the polarity of metal oxide, the theoretical basis has been little established. Interestingly, the artificial polarity imposed on surface can be induced by constructing superlattice of metal oxides. Therefore, we aim to study electronic properties of superlattices with two different rutile metal oxides. We suggest several (110) superlattice systems in consideration of elastic constants of metal oxides in bulk phase by using density functional theory (DFT) calculation. The systems were modeled in two ways; layer on bulk substrate system and thin layers-stacking system, which exhibited the different electronic properties. The variations of the band gaps and electronic properties were observed through density of state (DOS) analysis. Lastly, in order to verify the performance of the superlattice systems as ORR catalyst, we investigated the adsorption behavior of oxygen molecule on the surface of superlattice system.