Enhancement mechanism of field electron emission properties in hybrid carbon nanotubes with tree- and wing-like features

Controlled growth of carbon nanotube–graphene hybrid materials for flexible and transparent conductors and electron field emitters

“…The 3.0NT-G film showed the lowest turn-on electric field of 2.9 V mm À1 and threshold electric field of 3.3 V mm À1 because it possessed the highest CNT density of 161 Â 10 8 cm À2 . The 3.0NT-G film exhibited the best field emission performance with a current density of 1.33 mA cm À2 at an applied field of 4.0 V mm À1 , which is better than that of randomly aligned CNT films on metal, 45,46 ITO glass, 47 Si, [48][49][50] and graphite, 51,52 and is comparable with an un-doped carbon nanotube array on graphene. To describe the electron emission from a metal surface under an applied electric field, the Fowler-Nordheim (F-N) theory is commonly used.…”

Methods for carbon nanotubes synthesis—review

“…They found that both the tree-and wing-like CNTs exhibited lower turn-on field and higher emission current density than the pristine CNTs, which can be ascribed to the effects of branch size, crystal orientation, and graphitic-sheet density. 126 Seo et al investigated the growth of metal-free MWNTs on Corning glass substrates with a microwave PECVD (MPECVD) method using methane and hydrogen gases. An amorphous carbon layer deposited with RF magnetron sputtering was used as a catalyst to grow metal-free CNTs.…”

Coral Reef‐Like Carbon Nanomaterial: Synthesis, Characterization and Mechanism Study

“…The tree‐like CNTs are defined as thin CNTs grown on the trunk or tips of pristine CNTs although some refuse this description and oppose it . In our study, we found that there is a natural occurring figure that can describe the branched‐like materials more specifically than the general term tree.…”

“…Raman spectrum for the coral reef‐like carbon nanomaterials as shown in Figure exhibits doublet at 1306.26 cm −1 and 1589.73 cm −1 with a relative intensity ratio (I D /I G ) of about 1.28 which could be characteristic of disordered carbon and is similar to the case of certain carbon nanotubes. This may be caused by the partial transfer of hybridized carbon from sp 2 to sp 3 on the walls of coral reef‐like carbon nanomaterials during deposition . The strong peak at 1589 cm −1 (G‐band) is closely related to the vibration in all sp 2 ‐bonded carbon atoms in a two‐dimensional hexagonal lattice namely the stretching modes of C=C bonds of typical graphite.…”

“…Plasma enhanced CVD was used to synthesize tree‐like carbon nanotubes (CNTs) with branches of different diameters and the wing‐like CNTs with graphitic‐sheets of different densities . Arc‐plasma assisted CVD from a coal‐based carbon anode using iron as catalyst was utilized to produce carbon micro‐trees with a diameter of 15–25 μm.…”