Thermal conductivity enhancement in gold decorated graphene nanosheets in ethylene glycol based nanofluid

M C Mbambo; M J Madito; T Khamliche; C B Mtshali; Z M Khumalo; I G Madiba; B M Mothudi; M Maaza

doi:10.1038/s41598-020-71740-1

Thermal conductivity enhancement in gold decorated graphene nanosheets in ethylene glycol based nanofluid

Sci Rep. 2020 Sep 7;10(1):14730. doi: 10.1038/s41598-020-71740-1.

Authors

M C Mbambo^{1

2

3}, M J Madito⁴, T Khamliche^{5

4}, C B Mtshali⁴, Z M Khumalo⁴, I G Madiba^{5

4}, B M Mothudi⁶, M Maaza^{5

4}

Affiliations

¹ UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria, South Africa. mbamboc@webmail.co.za.
² iThemba LABS-National Research Foundation, 1 Old Faure Road, PO Box 722, Somerset West, Western Cape Province, 7129, South Africa. mbamboc@webmail.co.za.
³ Department of Physics, College of Science, Engineering and Technology, University of South Africa, Private Bag X6, Florida, Johannesburg, 1710, South Africa. mbamboc@webmail.co.za.
⁴ iThemba LABS-National Research Foundation, 1 Old Faure Road, PO Box 722, Somerset West, Western Cape Province, 7129, South Africa.
⁵ UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria, South Africa.
⁶ Department of Physics, College of Science, Engineering and Technology, University of South Africa, Private Bag X6, Florida, Johannesburg, 1710, South Africa.

Abstract

We report on the synthesis and thermal conductivity of gold nanoparticles (AuNPs) decorated graphene nanosheets (GNs) based nanofluids. The GNs-AuNPs nanocomposites were synthesised using a nanosecond pulsed Nd:YAG laser (wavelength = 1,064 nm) to ablate graphite target followed by Au in ethylene glycol (EG) base fluid to obtain GNs-AuNPs/EG hybrid nanofluid. The characterization of the as-synthesised GNs-AuNPs/EG hybrid nanofluid confirmed a sheet-like structure of GNs decorated with crystalline AuNPs with an average particle diameter of 6.3 nm. Moreover, the AuNPs appear smaller in the presence of GNs which shows the advantage of ablating AuNPs in GNs/EG. The thermal conductivity analysis in the temperature range 25-45 °C showed that GNs-AuNPs/EG hybrid nanofluid exhibits an enhanced thermal conductivity of 0.41 W/mK compared to GNs/EG (0.35 W/mK) and AuNPs/EG (0.39 W/mK) nanofluids, and EG base fluid (0.33 W/mK). GNs-AuNPs/EG hybrid nanofluid displays superior enhancement in thermal conductivity of up to 26% and this is due to the synergistic effect between AuNPs and graphene sheets which have inherent high thermal conductivities. GNs-AgNPs/EG hybrid nanofluid has the potential to impact on enhanced heat transfer technological applications. Also, this work presents a green synthesis method to produce graphene-metal nanocomposites for various applications.