A hollow titanium oxynitride nanorod array as an electrode substrate prepared by the hot ammonia-induced Kirkendall effect

Abstract

The Kirkendall effect has been widely employed for the preparation of hollow nanostructures along with galvanic replacement and Ostwald ripening as a non-templating method. Despite many successful demonstrations for Kirkendall void formation, they have been mostly confined to the synthesis of hollow metal oxides and sulfides. In this work, we explored the feasibility of the Kirkendall effect for the preparation of a nitride compound in an effort to extend its peculiar merits, and discovered a new mechanism of Kirkendall void formation in the synthesis of hollow titanium oxynitride arrays by the nitridation of TiO₂. Our in-depth study revealed that the reduction power of hot NH₃ played a crucial role in the formation of the Kirkendall void. When employed as an electrode substrate for supercapacitor applications, the hollow titanium oxynitride array showed a superior capacitive performance, which is ascribed to its high electrical conductivity and low density.