Thermochemical Modeling on Graphene Nanosheet Film Exfoliation

Graphene based nanosheet films have gained popularity for use in various applications such as energy storage, selective membranes, semiconductors, and catalysis. Thermal exfoliation is an efficient method for large scale production of reduced graphene nanosheet or reduced graphene oxide (rGO) films. The full thermal exfoliation will lead to the destruction of the original film cast body. As such, partial thermal exfoliation may be used to manufacture rGO films in the original geometry with needed properties. This research provides a simple novel methodology in synthesizing uniform, flexible, and planar rGO films and provides findings acquired through theoretical modeling. The modeling is performed by applying an energy balance on the film during exfoliation. This model considers the heat accumulation, chemical reaction, and the convective heat transfer with the environment. The model is applied to obtain thermal properties and reaction rate law for rGO films. In addition, these constants are used to provide a theoretical sample temperature curve, which has minimal square sum difference with the experimental exfoliation curve. This yields a model that can effectively reproduce various thermochemical processes involving GO thermal exfoliation. Namely, reaction order, activation energy, enthalpy of reaction, specific heat capacity and activation energy were found to be, respectively: 1.59, 196 kJ/mol, 1217 J/g, and 255 J/g K. Modeling GO film thermal exfoliation gives a better understanding of key properties that will aid in fabrication of these rGO films for use in various applications.