High-yield production of graphene flakes using a novel electrochemical/mechanical hybrid exfoliation

This research aims to develop a novel hybrid process of an electrochemical intercalation and mechanical exfoliation for fabricating graphene flakes. Using a rotational tool as electrode, the graphite powders were electrochemically intercalated using ions in electrolyte, and then the expanded graphite powders were mechanically exfoliated for few-layer graphene flakes. To obtain the high-quality graphene flakes, the graphite powders were intercalated in the mixed electrolyte of myristyl alcohol surfactant added in H₂SO₄ solution at the speed of the rotational tool of 2000 rpm and the applied voltage of ± 4 V for 1 h, and then the expanded graphite powders were mechanically exfoliated at the speed of the rotational tool of 10000 rpm for 1 h. The average thickness and lateral size of the graphene flakes was 1.42 nm and 0.5 μm measured by an atomic force microscope, respectively. The maximum C/O and I_2D/I_G ratios of graphene flakes were 22.29 and 1.22 analyzed by an X-ray photoelectron spectroscope and a Raman spectrometer, respectively. Besides, the production yield of the exfoliated few-layer graphene flakes was evaluated that could achieve to 20%, which was approximately 2 times more than the pure electrochemical or pure mechanical exfoliation methods.