Electrochemical Exfoliation of Graphite: Effect of Temperature and Hydrogen Peroxide Addition

Controlling the defect density in graphene is critical to manipulate materials properties and functionality through synthesis and processing. In this work, graphene was prepared by electrochemical exfoliation method at different temperatures from 25 to 95 °C with and without the addition of H₂O₂. The effect of both the exfoliation temperature and H₂O₂ addition on governing the defect density and oxygen functional groups in graphene was investigated using Raman spectroscopy analysis and thermogravimetric analysis (TGA), respectively. The number of defects, which can be edge defect or oxygen functional groups, decreases with the increase of exfoliation temperature from 25 to 95 °C. This can be explained by nucleophilicity of hydroxyl ions and peroxide ions. The thermal stability of the as-synthesized graphene increases with increasing exfoliation temperature and the amount of H₂O₂ addition. Transmission electron microscopy (TEM) was performed to characterize the morphology and the layer number of the as-synthesized graphene.