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.

in this paper we present a facile method for the synthesis of aminated graphene derivative through simultaneous reduction and amination of graphene oxide via two-step liquid phase treatment with hydrobromic acid and ammonia solution in mild conditions. the amination degree of the obtained aminated reduced graphene oxide is of about 4 at.%, whereas C/O ratio is up to 8.8 as determined by means of X-ray photoelectron spectroscopy. the chemical reactivity of the introduced amine groups is further verified by successful test covalent bonding of the obtained aminated graphene with 3-Chlorobenzoyl chloride. The morphological features and electronic properties, namely conductivity, valence band structure and work function are studied as well, illustrating the influence of amine groups on graphene structure and physical properties. particularly, the increase of the electrical conductivity, reduction of the work function value and tendency to form wrinkled and corrugated graphene layers are observed in the aminated graphene derivative compared to the pristine reduced graphene oxide. As obtained aminated graphene could be used for photovoltaic, biosensing and catalysis application as well as a starting material for further chemical modifications.

We present a study of the process of reduction of thin graphene oxide (GO) films consisting of flakes with lateral size of up to 100 μm through soft ultraviolet irradiation in the argon atmosphere. It was found out that the reduction process leads to a significant decrease in the overall content of the basal-plane functional groups, namely, epoxides and hydroxyls, but with simultaneous increase in the total number of the edge-located carboxyl groups. Obtained transmission electron microscopy images showed that this effect is related to formation of nanoscale holes in the course of reduction. Based on the data obtained, we have proposed a mechanism of the observed GO structural modification in terms of photoinduced chemical reactions between the carbon network and functional groups. These reactions result in progressive growth of the initially existing and newly formed vacancies with formation of the nanoholes with size of up to 100 nm. Thus, reduced graphene oxide films with the restored conjugated network and many edges terminated with carboxyl groups can be probably obtained via the photoreduction process in the argon atmosphere and further used in several applications, such as production of gas sensors and organic light-emitting devices.

No abstract

No abstract