We have investigated the electronic and magnetic properties of ð3; 3Þ and ð4; 4Þ single-walled carbon nanotubes (SWNTs) filled with 3d transition metal (TM) monatomic chains, using first-principles calculations based on the density functional theory to get a thorough understanding of metal atom-filled carbon nanotubes. We have found that the magnetic moment of 3d TM-filled SWNTs decreases when the TM atom changes from smaller atomic radius to larger atomic radius or, when the diameter of the SWNT decreases. Specifically, the magnetic moment increases as the bonding strength between a TM atom and carbon atoms decreases.

We investigated the adsorption of hydrogen peroxide molecules on Fe-filled single-walled carbon nanotubes (SWNTs) based on density functional theory (DFT) calculations. The adsorption possibilities for the hydrogen peroxide molecule were tested by finding the minimum energy as a function of distance of the molecule from the Fe-filled SWNT. Stable structures were obtained by optimizing the hydrogen peroxide (H(2)O(2)) as it was adsorbed on to the Fe-filled SWNT. This study may serve as an initial investigation into the possibility of Fe-filled single-walled carbon nanotubes (SWNTs) as catalyst material for the proton exchange membrane fuel cell (PEMFC).

aIn the previous studies, the stable structures and magnetic properties of Fe-filled single-walled carbon nanotubes (SWNTs) on Ni (111) were investigated based on first principles calculations. The SWNT transformed into arch-like structure when the Fe atom was placed inside it near the Ni surface.In order to fully understand the formation of nanoarch when placed near the metal surface, we have provided a detailed mechanism of the bond-breaking of SWNT and the bond-making of SWNT-Fe and Ni surface.The electron distributions and the number of electrons in the majority and minority spins per atomic orbital were discussed.

The authors investigated the stable structures of (5, 5), (4, 4), and (3, 3) single-walled carbon nanotubes (SWNTs) on the Ti(0001) surface using first-principles calculations based on the density functional theory. They have found that SWNTs with decreasing radius adsorb greatly and transform into archlike structures on the Ti surface. The sp2 orbital characteristics of the carbon atoms hybridized to sp3 orbitals as they bind with Ti atoms and retain their conducting properties. Therefore, they expect that SWNTs with small radii can be used as electronic devices because of its stability on the electrode surface.