Environment-friendly route for stable aqueous dispersion of reduced graphene oxide for heat transfer application

A simultaneous functionalization and reduction route to prepare stable dispersion of reduced graphene oxide from graphene oxide has been described. Diethanol amine has been introduced for the first time as an environment friendly reducing agent in a simple reflux reaction. Diethanol amine acts as a reducing agent and helps to enhance the stability of dispersion, making hydrogen bonding by virtue of two functional groups. The prepared dispersion of 0.025 mg/mL concentration is stable for months together and has a zeta potential value -45 V at room temperature. UV-Vis study shows peak at 264 nm that is signatory for reduced graphene oxide. TEM images confirm spread thin sheets of graphene of few hundred nanometer lateral dimension. Thermal diffusivity studies suggest nearly 60% enhancement for the dispersion in comparison to base fluid, water. This suggests graphene dispersion is promising for heat transfer applications.