Synthesis of Hollow N,P-Doped Carbon/Co 2 P 2 O 7 Nanotubular Crystals as an Effective Electrocatalyst for the Oxygen Reduction Reaction.

Herein, N,P-rich carbon/carbon/Co 2 P 2 O 7 hollow nanotubes with a multilayered wall structure were successfully fabricated for the ORR electrocatalyst. The hollow tube structure catalysts were obtained by carbonizing Co 2 P 2 O 7 /C coated with the phytate-doped PANI. The Co 2 P 2 O 7 /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/cm 2 . 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.