Structural evolution and electrocatalytic application of nitrogen-doped carbon shells synthesized by pyrolysis of near-monodisperse polyaniline nanospheres

Near-monodisperse polyaniline (PANI) colloids with controlled particle size (55-90 nm) were prepared by disperse polymerization of aniline in the presence of a steric stabilizer: polyvinylpyrrolidone (PVP). The silica-coated PANI colloidal nanospheres were further subjected to pyrolysis treatment at different temperatures (400-950 degrees C) to fabricate the nitrogen-doped carbon shells (NCSs). The NCSs so obtained were found to have controllable morphologies and pore sizes (13.4-23.2 nm). A possible structural evolution of the PANI colloids during pyrolysis process is proposed based on results obtained from a variety of characterization techniques. Upon loading Pt metal, the supported Pt/NCS catalysts were found to exhibit superior catalytic performance during electrooxidation of methanol, surpassing that of the conventional Pt/Vulcan XC-72 catalyst. The effects of nitrogen doping and carbon shell structure on Pt dispersion, tolerance of CO poisoning, and electrochemical properties are also examined and discussed.