Nanocomposites and nanomaterials

Electrocatalytic properties of the mechanochemicaly prepared 2D-materials in hydrogen and oxygen reduction reactions
Kozarenko O.A., Kondratyuk A.S., Posudievsky O.Yu., Koshechko V.G., Pokhodenko V.D.
L.V. Pisarzhevsky Institute of Physical Chemisrtry of the National Academy of Science of Ukraine. Prospect Nauki, 31, Kyiv-03028, Ukraine. 
E-mail: kozarenko-olga@ukr.net

This work is devoted to the study of the electrocatalytic properties of 2D-materials in hydrogen reduction and oxygen reduction reactions. We used a highly efficient and “green” mechanochemical method that does not require the use of toxic solvents to prepare these materials. 
The nanocomposites gMoS2/Gr и gMoSe2/Gr were prepared by simultaneous mechanochemical delamination of bulk molybdenum disulfide and diselenide with graphite. These materials exhibit high electrocatalytic properties in the hydrogen reduction reaction (HER) from water. It has been established that glassy carbon electrode modified with the prepared electrocatalysts is capable to stable operating for long time at overpotential 300 mV and to provide current density ~100 mА/сm2 in case of gMoS2/Gr and ~140 mА/сm2 in case of gMoSe2/Gr.
It has been shown that mechanochemical doping of multilayer graphene with nitrogen by itself (Gr-N) and along with fluorine (Gr-N,F) improves their electrocatalytic properties in oxygen reduction reaction (ORR) in alkaline medium. It has been established that the nature of doping atoms effects on activity of graphene in ORR. The introduction of such electronegative atom as fluorine to the graphene structure leads to some deterioration of its electrocatalytic properties. It leads to increase of the electricity quantity expended on 2ē-mechanism in ORR as well as shift of the onset potential to more negative range in comparison with Gr-N. It has been established that Gr-N is able to stable operating for at least 5 hours as electrocatalyst in ORR and possesses high methanol and CO tolerance.