Hexagonal Boron Nitride Coated Carbon Nanotubes: Interlayer Polarization Improved Field Emission

Abstract

Coating of h-BN onto carbon nanotubes induces polarization at interfaces, and charges become localized at N and C atoms. Field emission of coated tubes is found to be highly stable, and current density fluctuates within 4%. Study further reveals that the electric field established between coatings and tubes facilitates charge transfer across interfaces and electrons are emitted through occupied and unoccupied bands of N and B atoms.

Facile Synthesis of Millimeter-Scale Vertically Aligned Boron Nitride Nanotube Forests by Template-Assisted Chemical Vapor Deposition

“…Figure 5a shows 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 and N-C bonds, respectively. 47 This clearly indicates the presence of BN coatings on the CNTs. These two peaks further shift to 1389 and 801 cm -1 , respectively, after the annealing process and are typical characteristics of BNNTs.…”

“…the weight loss is due to the small traces of carbonaceous residues due to the growth and annealing process, respectively 47. It should be noted that carbon residues are observed in both the EELS and XPS spectra for the as-fabricated BNNTs.…”

“…The first is to employ a chemical conversion process by substitution of boron (B) and nitrogen (N) atoms in replacement for carbon (C), [40][41][42][43][44][45] and the second is by coating the CNTs with BN layers. [46][47][48][49][50] The former, however, requires very high temperature of above 1500 °C and the longest BNNTs formed by conversion could extend up to several microns. 41,42 It should be noted that this method mostly yields semiconducting BN doped CNTs at lower temperatures.…”

“…41,42 It should be noted that this method mostly yields semiconducting BN doped CNTs at lower temperatures. [43][44][45] For the latter, enhanced field emission properties have been observed for BN coated CNTs (BN/CNTs), 47,48,50 and the BN encapsulation can act as a protective layer against oxidation for CNTs. 47,49 However, to the best of our knowledge, fabrication of millimeters-long VA-BNNTs through such coating technique has not been explored.…”

Engineering the interface characteristics on the enhancement of field electron emission properties of vertically aligned hexagonal boron nitride nanowalls

“…A significant improvement of the field emission characteristics was reported for a graphite nanofiber coated with a hBN nanofilm . Moreover, field emission characteristics of carbon nanotube arrays were much improved by coating with hBN films .…”