Synthesis of Hollow N,P-Doped Carbon/Co₂P₂O₇ Nanotubular Crystals as an Effective Electrocatalyst for the Oxygen Reduction Reaction

Abstract

Herein, N,P-rich carbon/carbon/Co₂P₂O₇ hollow nanotubes with a multilayered wall structure were successfully fabricated for the ORR electrocatalyst. The hollow tube structure catalysts were obtained by carbonizing Co₂P₂O₇/C coated with the phytate-doped PANI. The Co₂P₂O₇/C was obtained by phosphorylating a basic cobalt carbonate with phytic acid (PA). Onset and positive half-wave potentials were measured at 0.90 and 0.84 V, respectively, with a diffusion-limited current density of 4.58 mA/cm². Effect of the thickness of polyaniline (PANI) in the electrocatalyst precursor was also investigated. The specific surface area as well as the content of graphitic N altered as the time of PANI polymerization increased, resulting in remarkably different catalytic activities. This study of hollow nanotube catalysts exhibits efficient noble-metal-free oxygen reduction reaction electrocatalysts for other chemical systems, which will provide abundant electrochemical active centers and sufficient energy.