Hierarchically tubular nitrogen-doped carbon structures for the oxygen reduction reaction

Abstract

Rational design and synthesis of nitrogen-doped carbon structures are promising for renewable energy applications such as the oxygen reduction reaction (ORR). Here we develop a hierarchically tubular nitrogen-doped carbon structure by a simultaneous etching and regrowth method, using Cu₂O nanowires as sacrificial templates. This hierarchical structure presents a large surface area (398 m² g⁻¹), attributed to the numerous tiny nanotubes grown on the surface of the hierarchical structure. In addition, a high nitrogen doping ratio (8.03%) with major pyridinic and graphitic nitrogen atoms is obtained, via the Cu–N interaction from original Cu₂O templates. This hierarchically tubular carbon structure exhibits excellent ORR catalytic activity, with high onset and half-wave potentials, large limiting current densities, and good stability.