ELECTROCHEMICAL DISPERSION OF GRAPHITE IN 58% NITRIC ACID TO PRODUCE MULTILAYER GRAPHENE OXIDE

Abstract

Electrochemical oxidation of graphite powder in 58% HNO3 was studied. Samples of oxidized graphite were obtained with a imparting of the amount of electricity 500, 700, 1500 mAh g-1. The character of the galvanostatic dependencies allows to select a region of the formation of intercalated compounds of graphite prior to the accumulation of quantity of electricity of 500 mA h g-1. It was found that when the quantity of electricity of over 700 mA h g-1 the process of electrochemical peroxidation of intercalated graphite begins with the formation of multilayer graphene oxide, as confirmed by comprehensive studies using X-ray diffraction, scanning electron microscopy, FTIR spectroscopy, laser diffraction. The synthesized multilayer graphene oxide is characterized by the presence of a spectrum of oxygen-containing functional groups, mainly hydroxyl, as well as carboxyl, epoxy and alkoxyl. X-ray images show a peak at 2θ = 11.45° which intensity increases for re-oxidized graphite compounds and also indicate the formation of a multilayer graphene oxide with an interlayer distance of 7.8 Å. The synthesized material in aqueous suspensions under the action of ultrasound is dispersed with a 7-11-fold reduction in particle size. Graphene layers remains layered structure but the degree of their deformation increases, and the thickness of the layers decreases with an increase in the imparted amount of electricity.