Part of the book: Carbon Nanotubes
In this chapter, we describe how structural parameters affect the reactivity of single-walled carbon nanotubes through global reactivity descriptors obtained by the DFT methods (B3LYP/6-31G(d) with real frequencies in all cases). First, we investigate regular armchair, chiral, and zigzag nanotubes with bumpy defects (five- and seven-membered rings), finding that regular and defective zigzag nanotubes exhibit the greater conductive ability, reactivity, and capacity of nanotubes to be reduced. The bumpy defects favor those properties with greater intensity in chiral nanotubes. We also investigate how the properties of armchair nanotubes change in the presence of bumpy, haeckelite, Stone-Wales, and zipper defects, and we found that armchair nanotubes with zipper defects show greater reactivity and better conducting abilities enhanced by nitrogen doping and longer nanotubes. In addition, for armchair nanotubes containing bumpy defects, our results reveal, considering B3LYP-D3 correction, that bumpy defects confer a greater ability to physically adsorb hydrogen, with adsorption energies of 0.32 eV/adsorbed H2. That value is considered ideal for the reversible adsorption of hydrogen at room temperature and low pressures and therefore favorable for use as a clean energy source. These results contribute to the future design of novel useful materials based in carbon nanotubes.
Part of the book: Density Functional Calculations