In the present work, a novel chemical reduction followed by calcination at considerably low temperature is used to synthesize copper oxide decorated graphene (CuO/HEG). Graphene has been synthesized via hydrogen induced exfoliation/reduction of graphite oxide. As-synthesized graphene is functionalized in acid medium to decorate copper oxide nanoparticles as well as to disperse it in polar medium. CuO/HEG is dispersed in deionized (DI) water and ethylene glycol without any surfactant, and the thermal transport properties of those nanofluids are studied. Thermal conductivity of CuO/HEG dispersed in DI water based nanofluid shows an enhancement of ∼28% at 25 AC for a volume fraction of 0.05%. In addition to thermal conductivity, the electrical conductivity of the nanofluids is also measured for different volume fractions at different temperatures. Heat transfer coefficient is measured in an indigenously fabricated setup for different volume fractions for different flow rates. © 2011 American Chemical Society.

Sundara Ramaprabhu

Department Of Physics

acid medium

Chemical reduction

COPPER OXIDE NANOPARTICLES

Electrical conductivity

Functionalized

GRAPHITE OXIDE

Low temperatures

Metal oxides

NANO-FLUID

Nanofluids

THERMAL TRANSPORT PROPERTIES

WATER BASED

Calcination

Deionized water

electric conductivity

Ethylene

Ethylene glycol

Graphene

Heat transfer

Metallic compounds

Nanofluidics

Surface active agents

Thermal conductivity of liquids

Titration

Transport properties

Volume fraction

Thermal conductivity

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Journal of Physical Chemistry C

The present study describes a facile synthesis procedure for nanocomposites consisting of 1D carbon nanotubes, 2D graphene and metal-oxide nanoparticles (CuO, ZnO) referred as metal-oxide dispersed on graphene-wrapped carbon nanotubes (CuO/GC and ZnO/GC) nanocomposites. Moreover, nanofluids were prepared by dispersing the above composites and the thermal conductivity of these nanofluids has been measured. Initially, GC was synthesized by a chemical vapor deposition technique using the mixture of graphene oxide (GO) and MmNi3 as catalyst and further purified by removing catalyst impurities and amorphous carbon. Afterwards, synthesis of metal-oxide dispersed on GC nanocomposites has been done. The formation of nanocomposites has been confirmed by X-ray diffraction, scanning electron microscope, and transmission electron microscope. Further, nanofluids were prepared by dispersing nanocomposites (GC, CuO/GC, and ZnO/GC) in de-ionized (DI) water and ethylene glycol (EG) without any functionalization and surfactant. After confirming the stability of nanofluids by zeta potential analysis, thermal conductivity of these nanofluids was measured at different temperatures. GC, ZnO/GC and CuO/GC dispersed DI water based nanofluids show an enhancement of 22.6%, 24.1% and 26.0% for 0.015 vol. % at 50 °C, respectively. Further, an enhancement of 15.5%, 17.7% and 21.2% was observed for GC, ZnO/GC and CuO/GC dispersed EG based nanofluids for 0.015 vol. % at 50 °C, respectively. © 2018 Elsevier B.V.

Thermochimica Acta

An experimental study on thermal conductivity enhancement of DI water-EG based ZnO(CuO)/graphene wrapped carbon nanotubes nanofluids

Herein, we report the fabrication of hydrogen gas sensors based on noble nanometal decorated one dimensional multi walled carbon nanotubes and two dimensional graphene by a simple drop casting technique, with practical applications in view. Pt decorated functionalized graphene sheets (Pt/f-G) and Pt decorated functionalized multi walled carbon nanotubes (Pt/f-MWNT) were synthesized and employed as hydrogen sensors. Systematic investigation of hydrogen sensing, at a low detection level of 4 vol% hydrogen in air, of (Pt/f-G) reveals a response time comparable to that of (Pt/f-MWNT) but with a two fold increase in the sensitivity at room temperature. These sensors were also found to be stable over repeated cycles of hydrogenation and dehydrogenation. © The Royal Society of Chemistry 2009.

Nanoscale

Nanostructured Pt decorated graphene and multi walled carbon nanotube based room temperature hydrogen gas sensor

Copper nanoparticle-loaded multiwalled carbon nanotubes (Cu/MWCNTs) have been synthesized by chemical reduction method using functionalized MWCNTs processed by the chemical vapor deposition technique and copper chloride. Cu/MWCNTs based nanofluids have been synthesized by dispersing nanocomposites of CuZ MWCNTs in deionized water (DI water) and ethylene glycol (EG) polar base fluids without any surfactant. The results showed that well-dispersed Cu/MWCNTs nanofluids with varying concentration of Cu/MWCNTs can be synthesized using the present method. A maximum thermal conductivity at a very low volume fraction of Cu/MWCNTs has resulted due to the homogeneous dispersion of Cu decorated MWCNTs in base fluids and formation of more hydrophilic MWCNTs due to the attachment of oxygen containing functional groups leading to a good interactions of MWCNTs with each other. © 2008 American Chemical Society.

Synthesis and thermal conductivity of copper nanoparticle decorated multiwalled carbon nanotubes based nanofluids

Usual heat transfer fluids with suspended ultra fine particles of nanometer size are named as nanofluids, which have opened a new dimension in heat transfer processes. The recent investigations confirm the potential of nanofluids in enhancing heat transfer required for present age technology. The present investigation goes detailed into investigating the increase of thermal conductivity with temperature for nano fluids with water as base fluid and particles of Al2O3 or CuO as suspension material. A temperature oscillation technique is utilized for the measurement of thermal diffusivity and thermal conductivity is calculated from it. The results indicate an increase of enhancement characteristics with temperature, which makes the nanofluids even more attractive for applications with high energy density than usual room temperature measurements reported earlier.

Fulltext

Journal of Heat Transfer

Temperature dependence of thermal conductivity enhancement for nanofluids

Electrochimica Acta

CuO/graphene composite as anode materials for lithium-ion batteries

International Communications in Heat and Mass Transfer

A comparison of experimental heat transfer characteristics for Al2O3/water and CuO/water nanofluids in square cross-section duct

Synthesis and transport properties of metal oxide decorated graphene dispersed nanofluids

Journal	Journal of Physical Chemistry C
ISSN	19327447
Open Access	No