Cables of BN-insulated B–C–N nanotubes

Abstract

Nanotubular ropes composed of aligned multiwalled nanotubes having electrically insulating BN-rich outer shells and semiconducting B–C–N inner shells were synthesized through the reaction of aligned CNx (x⩽0.1) nanotube mats with boron oxide and nitrogen at ∼2000–2110 K. The atomic structure and chemical composition of the ropes were analyzed by high-resolution transmission and energy-filtered (Omega filter) electron microscopy. Individual ropes display perfect insulating performance of BN-rich outer layers and excellent field emission and thus conductive properties of inner B–C–N layers. A semiconducting nanometer-scale cable with built-in electrical insulation has thus been realized.

Enhanced electrical conductivities of N-doped carbon nanotubes by controlled heat treatment

“…3 (b, c)). 20 In this context, the introduction of N atoms into the graphitic layer is known to create pentagons which facilitate the formation of distorted or defective layers. 40,46 We noted a distinctive change in the HRTEM images for nanotubes that were thermally treated at 1000 °C and 1500 °C (Fig.…”

“…5 (c)). The N 1s peak was deconvoluted into four peaks: the peak located at 398.5 eV 20 corresponds to pyridine-like N, the peak located at 400.1 eV from the pyrrolic N; the strong signal at 401.4 eV originated from the quaternary graphite-like N or substitutional N; and a weak peak located at 402-405 eV is assigned to an oxygenated N group. 51,52 When as-grown N-MWNTs (containing 2.7 at % of N) were 25 thermally treated at 1000 °C, preferential evolution of the oxygenated N atoms was observed (N content of 0.78 at %; see Table 1), which resulted in a large decrease in the electrical resistance of the individual nanotubes from 54 kΩ to 0.5 kΩ.…”

“…The electrical resistivity of NMWNTs in the bulk state was measured using the four-point 15 probe method (Mitsubishi Chemical, PD-51). The electrical resistance of an individual carbon nanotube was measured by the following procedure: a nanotube suspension was spin-coated on SiO 2 electrode, and the electrode patterns were formed by depositing tungsten (W) on an individual carbon nanotube by 20 focused-ion-beam lithography (SMI2059, SII, Japan), in order to exclude the contact resistance between the carbon nanotube and the electrode. The intrinsic resistance was obtained from the linear current-voltage relationship from -1 to 1 V (Advantest, TR-6143).…”

“…[4][5][6][7][8][9][10][11][12][13][14][15][16][17] The N-doped carbon nanotubes have showed metallic behavior, characterized by the presence of a donor state close to the Fermi level. [18][19][20][21][22][23] In addition, they may have potential applications as efficient supporting materials for 30 anchoring catalytic particles [24][25][26] ; as catalysts for the oxygen reduction reaction in fuel cells [27][28][29][30] ; as high-performance electron field emitters 20,[31][32][33] ; as a highly selective electron transport materials for solar cell 34 ; and as a multifunctional filler in polymeric composites [35][36][37] . In addition, the incorporation of N 35 atoms is known to improve the biocompatibility of carbon nanotubes 38 .…”

Fluorination of CN x Nanotubes

“…N-doping of carbon nanotubes yields electron-rich strictures [5] characterized by metallic behavior and high density of field emission current. [6] In this work, we studied the reactivity of CN x nanotubes towards the fluorinating agent BrF 3 .…”