Spaced TiO2 nanotube arrays allow for a high performance hierarchical supercapacitor structure

Abstract

In this work, we describe the synthesis and electrochemical properties of nitridated hierarchical TiO₂ nanotubes as an electrode for supercapacitors. The hierarchical TiO₂ nanostructures are formed by a controlled layer-by-layer TiO₂ nanoparticle decoration on self-organized spaced TiO₂ nanotubes. These structures are then annealed in a NH₃ atmosphere at elevated temperature to convert the material to a nitride structure – this drastically enhances their electron-transport properties. The areal capacitance of hierarchical structures can be tuned by changing the number of decorated TiO₂ nanoparticle layers. The capacitance enhancement of the hierarchical structures reaches a maximum when the surface area through nanoparticle deposition is highest and the conductivity via nitridation is optimized.