Chemisorption of Transition-Metal Atoms on Boron- and Nitrogen-Doped Carbon Nanotubes: Energetics and Geometric and Electronic Structures

The well-defined binding between transition-metals (TM) and the sidewall of carbon nanotubes (CNTs) plays a key role in the performance of CNT-based nanoelectronics, as well as the stability of catalysts used in either heterogeneous catalysis or fuel-cell electrocatalysis. Spin-polarized density functional theory calculations demonstrate that either boron or nitrogen doping can increase the binding strength of TM atoms with single-wall carbon nanotubes (SWCNTs), and comparatively, boron doping is more effective. The binding nature can be identified as chemisorption, based on the magnitude of the binding energy and the formation of multiple bonds. The chemisorbed TM atoms can modify the electronic structure of the doped nanotubes in various ways, depending upon the TM and helicity of the CNT, rendering the TM/doped-SWCNT composite viable for a wide range of applications. A total of 11 technologically relevant TMs adsorbed on two distinct and stable doped-SWCNT models have been investigated in this study. The doping sites are arranged in either a locally concentrated or uniform fashion within semiconducting SWCNT(8,0) and metallic SWCNT(6,6). The results serve as a starting point for studying larger, more complex TM nanostructures anchored on the sidewall of boron- or nitrogen-doped CNTs.