Electrochemical Deposition of Copper in Graphene Quantum Dot Bath: Pool Boiling Enhancement

Copper-graphene composite is synthesized by electrochemical deposition of copper in graphene quantum dot (GQD, 5% w/v) bath and is characterized by electrochemical and spectroscopic techniques. The electrochemical formation of the composite has been investigated by cyclic voltammetry that reveals the oxidation of the composite produces convection at the electrode. From the interaction of GQD with cupric ion the life time of the excited state of GQD has been estimated to be 4.1 × 10 −9 s. The morphology of the composite is having a string like structure as compared to normal cauliflower like copper deposition. Energy Dispersion Analysis X-ray spectrum (EDAX) shows distinct peaks at 0.25 eV and 8.1 keV that are identifiable as due to carbon and Cu of the composite. The copper-graphene composite gave a critical heat flux (CHF) of 216 W/cm 2 and a heat transfer coefficient (HTC) of 86 kW/m 2 C in pool boiling experiments. High speed images were taken using a Photron fastcam for determining the bubble departure diameter. The graphene-copper composite resulted in a 66% increase in CHF over a plain copper surface suggesting it to be an attractive option for pool boiling enhancement. The improved performance has been attributed to the higher thermal conductivity of the graphene layers arising from the porous nature of the surface with an increased surface area.