Nanocomposites and nanomaterials

Mechanochemical preparation, structure, physico-chemical characteristics and promising applications of modified graphenes and 2D g-C3N4
A.S. Kondratyuk, O.A. Kozarenko, O.Yu. Posudievsky, V.G. Koshechko, V.D. Pokhodenko
L.V. Pisarzhevsky Institute of Physical Chemistry of the National Academy of Sciences of Ukraine. Prospect Nauki 31, Kiev 03028, Ukraine. E-mail: kon_an@ukr.net

High intensity of research on 2D materials, in particular graphene and its analogue 2D g-C3N4, is due to the prospects for their application in electronics and optoelectronics, energy storage and conversion, catalysis, biology, medicine, and other fields. Physicochemical characteristics of graphene can be changed by doping its lattice with various heteroatoms or grafting functional groups to the carbon skeleton. At the same time, 2D g-C3N4 is a quite chemically inert wide band gap semiconductor which can be used for photo- and photoelectrochemical hydrogen evolution, water pollutants photodegradation and other applications. Despite the rapidly growing number of publications in the field of 2D materials, it is still important to develop efficient and convenient methods of their preparation and modification.
We have developed the mechanochemical methods for preparation of few-layer and monolayer nitrogen and fluorine co-doped graphene, nitrogen doped graphene and monolayer g-C3N4. The prepared 2D materials were characterized using a complex of mutually complementary experimental methods. 
It was shown that the prepared 2D g-C3N4 exhibits high photocatalytic activity in the photocatalytic hydrogen evolution from water under AM1.5G irradiation due to monolayer morphology, high reduction potential, as well as efficient separation and transfer of the photogenerated charges.
It was also found that the doped few-layer graphenes are characterized by a rather high electrocatalytic activity in oxygen reduction reaction. Besides electrocatalytic activity, the glassy carbon electrode modified with nitrogen and fluorine co-doped graphene exhibits the ability to resolve electrochemical responses of biologically active compounds like dopamine, ascorbic and uric acid.