INVESTIGATION OF PROCESS OF ELECTROCHEMICAL GRAPHITE DELAMINATION

In this work, the processes occurring during the electrochemical dispersion of graphite in a solution of sulfuric acid are investigated. The possibility of obtaining colloidal graphene solutions by combining electrochemical and ultrasonic graphite dispersion is shown. It is established that an increase in the operating voltage on the cell leads to the formation of a larger number of surface oxygen-containing groups. This allows increasing the yield of nanoscale particles. Ultrasonic treatment leads to an additional splitting of graphene plates and separation of nanosized particles from insufficiently oxidized particles of graphite. The thickness of graphite particles at each stage of obtaining nanoparticles was studied by X-ray diffraction analysis. It is established that as a result of electrochemical stratification a mixture of large undecomposed graphite particles and nano-sized graphite plates is formed. By ultrasonic dispersion with the subsequent classification of particles, it is possible to obtain colloidal solutions of low-layer graphene with a plate thickness of the order of 1 nm. At a working voltage of the cell equals to 10 V, the yield of nanoparticles is 10%, the change in the operating voltage does not significantly affect the concentration of the resulting colloid. The effect of adding nonionic and anionic surfactants to ultrasonic treatment of electrochemically dispersed graphite on the yield of a nanosized phase and the concentration of the resulting colloid is studied. The use of a nonionic surfactant (OP-10) negatively affects both the yield of nanoparticles and the concentration of the resulting colloid. The use of sodium dodecyl sulfonate in the stage of ultrasonic dispersion makes it possible to increase the yield of nanoparticles to 22% and the concentration of graphene particles in the colloid to 2.7 g/l. The obtained colloidal solutions are stable for more than a year. During this time there was no precipitation observed.