Effect of anion species on preparation and properties of pitch-based activated carbon fibers by in-situ catalytic activation of metal nanoparticles

The pitch-based activated carbon fibers (ACFs) were prepared from ethylene tar-derived pitches containing nickelocene (CNi) or nickel nitrate (NiN). The effects of different anions and contents of metal salts on the microstructure and surface chemical properties of fibers were investigated. The results revealed that Ni 2+ from CNi mainly remained its pristine molecule in the organometal salt-derived pitch (OP- x CNi), while Ni 2+ from NiN occurred complexation reaction with polycyclic aromatic hydrocarbons (PAHs) in the inorganic metal salt-derived pitch (IP- x NiN) due to the weaker binding ability between anions and Ni 2+ of CNi than CNi. The XRD and SEM results confirmed that IP-3NiN-ACF contained Ni, NiO, Ni 2 O 3 nanoparticles with different size distributions, while OP-3CNi-ACF only contained more uniformly distributed Ni nanoparticles with small size. Furthermore, OP-3.0CNi-ACF presented higher specific surface area of 1862 m 2 /g and a pore volume of 1.69 cm 3 /g than those of IP-3.0NiN-ACF due to the formation of pore structure during the in-situ catalytic activation of different metal nanoparticles. Therefore, this work further pointed out that the desired pore structure and surface chemistry of pitch-based ACFs could be obtained through regulating and controlling the interaction of anion species, metal cations and PAHs during the synthesis of pitch precursors. Graphical abstract