Polyacrylonitrile-Based Composite Carbon Nanofibers with Tailored Microporosity

Abstract

Carbon nanofibers are currently used in many applications including electrochemical power sources, particularly, fuel cells. Their properties are highly dependent on the micro- and mesoporous structure. Here we provide a porosimetric analysis of the polyacrylonitrile-based electrospun composite Zr- and Ni-containing carbon nanofiber mats by N2 and CO2 adsorption methods for the first time. It was found that pyrolysis temperature affects specific surface area and volume: the values increase for the sample pyrolyzed at 900 °C compared with the initial stabilized nanofibers (300 °C, air) according to the Dubinin --- Radushkevich, non-local density functional theory (NLDFT) and grand canonical Monte-Carlo methods (GCMC). For higher pyrolysis temperatures (1000 and 1200 °C), the porosimetric parameters decrease compared with the one pyrolyzed at 900 °C. According to the NLDFT and GCMC pore size distribution, the difference for pyrolyzed samples is mostly related to a sharp decrease in the specific surface area for pores with a size of ~ 0.5 nm and an increase for pores at 0.55--0.8 nm compared with the initial stabilized sample. The study demonstrates a way to adjust porosimetric parameters depending on the pyrolysis conditions of the nanofiber mats, since it can improve characteristics of such type of carbon materials in electrochemical devices