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.

This paper reports a facile and green method for conversion of graphene oxide (GO) into graphene by low-temperature heating (80 °C) in the presence of a glass wafer. Compared to conventional GO chemical reduction methods, the presented approach is easy-scalable, operationally simple, and based on the use of a non-toxic recyclable deoxygenation agent. The efficiency of the proposed method is further expanded by the fact that it can be applied for reducing both GO suspensions and large-scale thin films formed on various substrates prior to the reduction process. The quality of the obtained reduced graphene oxide (rGO) strongly depends on the type of the used glass wafer, and, particularly, magnesium silicate glass can provide rGO with the C/O ratio of 7.4 and conductivity of up to 33000 S*cm⁻¹. Based on the data obtained, we have suggested a mechanism of the observed reduction process in terms of the hydrolysis of the glass wafer with subsequent interaction of the leached alkali and alkali earth cations and silicate anions with graphene oxide, resulting in elimination of the oxygen-containing groups from the latter one. The proposed approach can be efficiently used for low-cost bulk-quantity production of graphene and graphene-based materials for a wide field of applications.

In this paper, we for the first time demonstrate efficient nitrogen doping of graphene oxide (GO) with nitrogen concentration of up to almost 5 at.% and desired type of the nitrogen species via modified Hummers’ method. Using x-ray photoelectron spectroscopy (XPS), x-ray absorption spectroscopy (XAS) and Fourier transform infrared spectroscopy (FTIR) techniques, we have found out graphitic nitrogen to be the dominant type of the implemented nitrogen species. At the same time, the subsequent GO thermal reduction to graphene appears to result in a transformation of the graphitic nitrogen into pyridines and pyrroles. The mechanisms of the observed GO nitrogen doping and conversion of the nitrogen species are proposed, providing an opportunity to control the type and concentration of the implemented nitrogen within the developed approach. A two-time increase of the graphenes’ conductivity is observed due to the performed nitrogen doping. Further comprehensive electrical studies combined with the transmission electron microscopy (TEM) and density functional theory (DFT) modeling have allowed us to estimate the conductivity mechanism and the impact of the implemented nitrogen. As a net result, a simple method to synthesize GO and graphene layers doped with specific nitrogen species is developed, which leads to new perspective applications for graphene, i.e. supercapacitors, catalysis, and sensors.