Hydrogenation, Purification, and Unzipping of Carbon Nanotubes by Reaction with Molecular Hydrogen: Road to Graphane Nanoribbons

Abstract

Reaction of single-walled carbon nanotubes (SWNTs) with hydrogen gas was studied in a temperature interval of 400-550 °C and at hydrogen pressure of 50 bar. Hydrogenation of nanotubes was observed for samples treated at 400-450 °C with about 1/3 of carbon atoms forming covalent C-H bonds, whereas hydrogen treatment at higher temperatures (550 °C) occurs as an etching. Unzipping of some SWNTs into graphene nanoribbons is observed as a result of hydrogenation at 400-550 °C. Annealing in hydrogen gas at elevated conditions for prolonged periods of time (72 h) is demonstrated to result also in nanotube opening, purification of nanotubes from amorphous carbon, and removal of carbon coatings from Fe catalyst particles, which allows their complete elimination by acid treatment.

Edge states in horseshoe-shape carbon nanotubes transformed by hydrogen adsorption

“…2, where both (6,6)CNT-H0b and (5,5)CNT-H0b are transformed into a horseshoe shape. Since a (1) was calculated in terms of the total energy of the pure CNT E tot (CNT), the total energy of the H 2 molecule E tot (H 2 ), and the total energy of the hydrogenated CNT E tot (CNT + 2H). Table I shows E b obtained by using several exchangecorrelation functionals, in comparison to a previous work.…”

“…1 The density functional theory (DFT) calculations have in fact shown that hydrogen adsorption on CNTs may lead to transformation of the CNTs or transformation into a horseshoe shape. [2][3][4][5][6][7] The H-induced transformation of CNTs, which is considered as an origin of the coalescence of single-wall CNTs, 3,8 can be employed for production of well-characterized graphene nanoribbons 1 similarly to the case of oxygen-induced transformation of CNTs.…”

Preparation of Ag–Fe-decorated single-walled carbon nanotubes by arc discharge and their antibacterial effect

“…Tylazin et al [25] have found that the reaction of SWCNTs with hydrogen gas at 550°C and at hydrogen pressure of 50 bar (5 MPa) can successfully remove all carbon coatings enclosing Fe particles in pristine samples. The H 2 -treatment temperature may be decreased at higher pressure to reduce the aggregation of Ag nanoparticles.…”

Novel graphene-based nanostructures: physicochemical properties and applications

“…83 Hydrogenation of CNTs also gives GNRs. 84 It was shown that hydrogenation at 400 ± 550 8C leads to opening of CNTs and formation of hydrogen-terminated GNRs. Yet another method 85 involves the oxidation of CNTs in a solution of PmPV in 1,2-dichloroethane.…”