Graphene-coated copper nanoparticles for thermal conductivity enhancement in water-based nanofluid

The integration of metallic nanoparticlcs (NPs) in nanofluids was found to enhance the thermal properties of the mixture and affect the rheological properties of the base liquid. However, due to their size and electrochemical properties, the added metallic nanoparticlcs have a limited contribution to the thermal transport and their stability hinders further development of such an approach in thermal management. We investigated in this work the effect of the presence of graphene as a coating layer of on copper nanoparticles dispersed in water as a water-based graphene coated copper nanofluid. Electronics microscopy was deployed to investigate the presence and the number of layers of graphene around the metallic nanoparticles. The observed particles were found to have a spherical morphology with a full coating of several layers. The elemental characterization of the NPs showed the presence of graphitic structure confirming the nature of the coating. The thermal properties of the fluid were estimated versus loading fraction of graphene coated nanoparticles and temperature using a hot disk method. An increase of up to 17% was recorded at a concentration of 0.1 w.% at 45deg C. Dynamic Light Scattering and zeta potential were used to investigate the electrochemical properties of the produced nanoparticles. The particles were found to present weak surface charges corresponding to a zeta potential of 6mV that promoted the segregation of the NPs. The rheological properties of the resulted fluids were investigated using viscometer. The NFs were found to have a Newtonian behaviour.