Microscopic Structure and Dynamics of Molecular Liquids and Electrolyte Solutions Confined by Carbon NanoTubes: Molecular Dynamics Simulations

Carbon nanotubes (CNT) are a completely new carbon material that are expected to become typical raw material for nanotechnology, applied to such broad fields as composite materials, electronic devices, drug delivery nanocapsules, etc. (Abrahamson & Nair, 2008; Abrikosov et al., 2005; Ahmad et al., 2006; Ajayan & Zhou, 2001; Avouris, 2002; Back & Shim, 2006; Bordjiba et al., 2008; Danilov et al., 2005; Eletskii, 1997; Hilder & Hill, 2008; Z. Liu et al., 2008; F. Yang et al., 2008; X. Yang et al., 2008; Zhang et al., 2007). One of the most interesting and promising is application of CNTs as electrode materials (Centeno et al., 2007; Janes et al., 2007; Huang et al., 2008; R. Lin et al., 2009). Nanoporous carbon exhibits excellent charge-discharge properties and a stable cyclic life. Moreover, activated composite carbon films generate high specific capacitance, laying the foundation for a new generation of double-layer super-capacitors (SC) (Endo et al., 2008; Huang, et al., 2008; Wu & Xu, 2006). CNT provides an ideal model for investigating the microscopic details of fluid transport in these nanoporous carbon structures. SC design requires polar, but aprotic solvents such as acetonitrile (AN). In spite of the great fundamental and practical importance of AN, its structural and dynamical properties inside CNTs have never been investigated yet. The fuel cells (Li et al., 2004; Maclean & Lave, 2003), which directly transform the chemical reaction energy between hydrogen and oxygen into electric energy, are seen as the energy source of the next-generation. With their environmentally friendly and high efficiency characteristics, the cells are being researched and developed as the future energy for automobiles and as energy generation for the houses. Since the CNTs have the possibility of clearly surpassing raw materials used so far, the aspects of applying it to fuel cell electrodes is under consideration (M.L. Lin et al., 2008). The most promising fuel cells are based on methanol (MeOH, CH3OH) which is renewable and easily storable (Convert et al., 2001; Gu & Wong, 2006; Hsieh & J.Y. Lin, 2009; Hsieh et al., 2009; H.S. Liu et al, 2006; Qi et al.; 2006;