Controllable-nitrogen doped carbon layer surrounding carbon nanotubes as novel carbon support for oxygen reduction reaction

Novel nitrogen-doped carbon layer surrounding carbon nanotubes composite (NC-CNT) (N/C ratio 3.3–14.3 wt.%) as catalyst support has been prepared using aniline as a dispersant to carbon nanotubes (CNTs) and as a source for both carbon and nitrogen coated on the surface of the CNTs, where the amount of doped nitrogen is controllable. The NC-CNT so obtained were characterized with scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption and desorption isotherms. A uniform dispersion of Pt nanoparticles (ca. 1.5–2.0 nm) was then anchored on the surface of NC-CNT by using aromatic amine as a stabilizer. For these Pt/NC-CNTs, cyclic voltammogram measurements show a high electrochemical activity surface area (up to 103.7 m2 g–1) compared to the commercial E-TEK catalyst (55.3 m2 g–1). In single cell test, Pt/NC-CNT catalyst has greatly enhanced catalytic activity toward the oxygen reduction reaction, resulting in an enhancement of ca. 37% in mass activity compared with that of E-TEK.