Sonoelectrochemical exfoliation of graphene in various electrolytic environments and their structural and electrochemical properties

Graphene synthesized via electrochemical exfoliation of graphite is considered to be a simple, fast, and scalable technique. This exfoliation technique leads to the formation of multi-layer graphene sheets with some defects, which is feasible for developing supercapacitor electrodes due to the presence of various pseudocapacitive functionalities. We report the exfoliation of multi-layer graphene via pulse sonication assisted electrochemical exfoliation technique (sonoelectrochemical) and studied the effect of three different aqueous electrolytes having acidic, neutral, and basic properties. The pulse (2/4) of 2 s sonication and 4 s rest time significantly improve the exfoliation process without hindering the electrochemical reaction that takes place on the graphite. The structural quality and functional groups attached to the surface of the exfoliated graphene sheets were evaluated using spectroscopic techniques. The investigation reveals that the nature of electrolyte and intercalation ions highly influences the exfoliation duration, yield, size, and quality of the graphene. The graphene layers exfoliated in sulfuric acid and ammonium sulfate electrolytes possessed many defect sites than those exfoliated in KOH. However, this graphene demonstrated better electrochemical performance than the graphene exfoliated in KOH electrolyte due to the presence of various electroactive defect sites on the surface and edges of the graphene.