Anomalous Electronic and Protonic Conductivity of 2D Titanium Oxide and Low-Temperature Power Generation Using Its Protonic Conduction

Abstract

In this study, a titanium-oxide film is fabricated by stacking 2D nanosheets with a thickness of 1 nm layer-by-layer. The electrical properties of the titanium-oxide film are investigated under various temperatures (25-300 degrees C) and a water vapor atmosphere. As a result, it is found that protonic conduction is dominant at low temperatures (<100 degrees C), while electronic conduction is highest at high temperatures (>200 degrees C). The electrical conductivity is about one billion times higher than that of conventional 3D titanium-oxide. Protons, dominant charge carriers at low temperature, are transported along the pathway between layers of nanosheets. The protonic conductivity is as high as 10(-4-5) S cm(-1) due to the increased interfacial density of the film. This anomalous electronic and protonic conduction is expected to be available in various applications. In this study, the developed 2D titanium-oxide with high protonic conductivity is employed in the solid electrolyte of a solid oxide fuel cell using water as a fuel. A competitive power density of approximate to 0.22 mW cm(-2) is obtained at low temperature (75 degrees C) under a water concentration gradient.