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 Ni2+ from CNi mainly remained its pristine molecule in the organometal salt-derived pitch (OP-xCNi), while Ni2+ from NiN occurred complexation reaction with polycyclic aromatic hydrocarbons (PAHs) in the inorganic metal salt-derived pitch (IP-xNiN) due to the weaker binding ability between anions and Ni2+ of CNi than CNi. The XRD and SEM results confirmed that IP-3NiN-ACF contained Ni, NiO, Ni2O3 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 m2/ g and a pore volume of 1.69 cm3/ 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.

    Abstract
        Graphical abstract
    1 Introduction
    2 Experimental
        2.1 Materials
        2.2 Preparation of spinnable pitch and pitch-based activated carbon fibers
        2.3 Material characterization
    3 Results and discussion
        3.1 Analysis of spinnable pitches
        3.2 Melt-spinning analysis of spinnable pitches
        3.3 Stabilization, carbonization and activation behaviors of pitch fibers
        3.4 Properties of pitch-based activated carbon fibers
        3.5 Catalytic activation mechanisms of pitch with metal nanoparticles
    4 Conclusions
    Acknowledgements 
    References

• Genchang Gou(Hunan Province Key Laboratory for Advanced Carbon Materials and Applied Technology, College of Materials Science and Engineering, Hunan University)
• Wenjie Wei(Hunan Province Key Laboratory for Advanced Carbon Materials and Applied Technology, College of Materials Science and Engineering, Hunan University)
• Jianxiao Yang(Hunan Province Key Laboratory for Advanced Carbon Materials and Applied Technology, College of Materials Science and Engineering, Hunan University)
• Jiahao Liu(Hunan Province Key Laboratory for Advanced Carbon Materials and Applied Technology, College of Materials Science and Engineering, Hunan University)
• Yue Liu(Hunan Province Key Laboratory for Advanced Carbon Materials and Applied Technology, College of Materials Science and Engineering, Hunan University)
• Jun Li(School of Chemistry and Biological Engineering, Changsha University of Science and Technology)
• Kui Shi(Hunan Province Key Laboratory for Advanced Carbon Materials and Applied Technology, College of Materials Science and Engineering, Hunan University)