ИСТИНА

A fast method for preparing aqueous graphene oxide (GO) dispersions by electrochemical oxidation of a graphite anode without preliminary intercalation with oxidizing agents is proposed. Ultrasonic probing was used in the modulation mode of ultrasonic waves (work/rest) for more efficient graphite oxidation exfoliation. It is shown that the mode of ultrasonic modulation 4/2 s is the most effective due to the probe material’s low corrosion while maintaining the optimum synthesis temperature not exceeding 30–35°C and achieving the best characteristics of the resulting product. Three cases of anodic oxidation of graphite to obtain graphene oxide were considered: (1) combined cathode–anode compartment; (2) split cathode-anode salt-bridged compartment; (3) separated anode compartment with a 3.5 kDa dialysis membrane. It has been determined that the approach to synthesis in a divided cathode-anode compartment makes it possible to obtain GO sheets with fewer defects when compared to chemical methods or methods in a combined cathode–anode compartment and makes it possible to control the oxidation degree of the material (C:O ratio), by varying current density. The prepared samples showed good stability for more than six months. The spectral and morphological characteristics were studied. Using chemiluminometry in the luminol, Co(II), and H2O2 system, the antioxidant properties concerning three key reactive oxygen species (H2O2, superoxide anion radical, and hydroxyl radical) were demonstrated. It has also been shown that the prepared GO dispersions do not induce lipid and phospholipid peroxidation.