Gas-Phase Oxidation of Spark Plasma Sintered Products of Covalently Crosslinked Carbon Nanotubes
Evgeniya V. Suslova, Vsevolod Epishev, Sergey V. Maksimov, К. И. Маслаков, O. Ya. Isaikina, Serguei V. Savilov
Abstract
Covalently crosslinked 3D structures of carbon nanotubes (CNTs) and CNTs with low-layer graphene fragments (LGFs) are obtained via the hydrolysis of 3-aminopropyltriethoxysilane with oxidized CNTs and/or LGFs. The resulting samples are consolidated into non-disintegrating pellets through spark plasma sintering at 1100°C and 30 MPa. Oxygen-containing groups are eliminated, and the LGF particles are transformed into a mixture of graphene sheets and onion-like carbon nanostructures. The resulting CNT consolidates and mixtures of CNTs with LGF have densities of 0.85 and 0.81 g cm−3 and conductivities of 42 and 57 S m−1, respectively. It is shown that the consolidated samples can be oxidized with nitric acid vapor without disturbing their 3D structure. When oxidative exposure time is increased from 3 to 6 h, the content of oxygen grows from 8.4 to 15.3 at % for 3D-crosslinked CNT structures, and from 14.0 to 16.1 at % for 3D-crosslinked CNT structures with LGFs.