Process regulation of the electrochemical exfoliation for graphene production with graphite powder as starting materials

Graphite powder as a raw material for the production of graphene by electrochemical exfoliation is superior to bulk graphite in terms of cost-effectiveness and manufacturing process. However, the current technology is still in its infancy and lacks preliminary systematic research. Therefore, there is a blank in the theoretical basis for process optimization and production regulation. Here, the effects of the main process parameters including graphite powder category, electric field driving force, electrolyte type, and corresponding concentration were systematically investigated on the electrochemical exfoliation and graphene quality. Expanded graphite powder with flake structure, regular graphite layer arrangement, and large graphite layer spacing is superior to natural flake graphite powder and artificial graphite powder for the electrochemical exfoliation to produce graphene. Sulfate ion with large ionic radius is best suitable for intercalation and subsequent expansion to obtain a high graphene yield and a low I D / I G in graphene in aqueous solution. For graphite powder as raw material, there exist optimal values for both electrolyte concentration and driving voltage for graphene production. A high graphene yield of 42.5% with low defect density ( I D / I G  = 0.14–1.43) and oxygen content of 30.54% can be obtained using Na 2 SO 4 at a concentration of 0.1 M at a voltage of 10 V for 4 h. The process optimization and regulation and corresponding influencing mechanisms of process parameters revealed here will provide guidance for the further development of graphene production by electrochemical exfoliation of graphite powder.