Abstract
Detonation nanodiamonds (NDs) were deposited on the surface of aligned carbon nanotubes (CNTs) by immersing a CNT array in an aqueous suspension of NDs in dimethylsulfoxide (DMSO). The structure and electronic state of the obtained CNT–ND hybrid material were studied using optical and electron microscopy and Infrared, Raman, X-ray photoelectron and near-edge X-ray absorption fine structure spectroscopy. A non-covalent interaction between NDs and CNT and preservation of vertical orientation of CNTs in the hybrid were revealed. We showed that current-voltage characteristics of the CNT–ND cathode are changed depending on the applied field; below ~3 V/µm they are similar to those of the initial CNT array and at the higher field they are close to the ND behavior. Involvement of the NDs in field emission process resulted in blue luminescence of the hybrid surface at an electric field higher than 3.5 V/µm. Photoluminescence measurements showed that the NDs emit blue-green light, while blue luminescence prevails in the CNT–ND hybrid. The quenching of green luminescence was attributed to a partial removal of oxygen-containing groups from the ND surface as the result of the hybrid synthesis.
Highlights
Detonation nanodiamonds (NDs) were deposited on the surface of aligned carbon nanotubes (CNTs) by immersing a CNT array in an aqueous suspension of NDs in dimethylsulfoxide (DMSO)
We showed that current-voltage characteristics of the CNT–ND cathode are changed depending on the applied field; below,3 V/mm they are similar to those of the initial CNT array and at the higher field they are close to the ND behavior
One could expect that a CNT–ND material with the CNTs oriented in predominant direction will have anisotropic properties
Summary
Field emission luminescence of nanodiamonds deposited on the aligned carbon nanotube array. Diamond-like carbon coating has been deposited on top of vertically aligned CNT film by PECVD method[1], and the composite film showed enhanced toughness. The use of vertically aligned micrometer-sized carbon fibers consisting of nested cones of graphene sheets yielded continuous deposition of ultrananocrystalline diamond film on the fiber surface, and the hybrid structures exhibited greatly improved field emission performance compared with the uncoated www.nature.com/scientificreports. Near-edge X-ray absorption fine structure spectroscopy (NEXAFS) examination revealed no changes in the electronic state of carbon fibers after the PECVD diamond film deposition. In the present paper we report for the first time the synthesis of an anisotropic CNT–ND hybrid material by impregnation of a CNT array with a suspension of NDs. It is shown that treatment of multiwall CNT array by DMSO–water suspension of NDs preserves vertical nanotube alignment toward substrate. Testing of CNT–ND hybrid under applied voltage reveals field emission electroluminescence of ND particles located at the array surface
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