Synthesis and thermo-physical properties of deep eutectic solvent-based graphene nanofluids

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Deep eutectic solvents (DESs) are emerging as promising media for various applications.
• Graphene oxide nanoparticles (GNPs) offer unique properties for thermal management.
• Surfactant-free nanoparticle dispersion in solvents remains a challenge.

Purpose of the Study:

• To synthesize and characterize novel graphene nanofluids (GNFs) using DESs.
• To investigate the stability and thermo-physical properties of these GNFs.
• To explore their potential as advanced heat transfer fluids.

Main Methods:

• Synthesized ammonium and phosphonium-based DESs with varying molar ratios.
• Dispersed functionalized graphene oxide nanoparticles (GNPs) at 0.01-0.05 wt% concentrations.
• Employed high-speed homogenization and ultrasonication for stable suspensions.
• Assessed nanofluid stability via visual observation, centrifugation, and zeta potential studies.
• Measured thermal conductivity and specific heat of the synthesized GNFs.

Main Results:

• Achieved homogeneous and stable graphene nanofluids without surfactants.
• Confirmed excellent dispersion and absence of particle agglomeration or sedimentation.
• Observed a maximum thermal conductivity enhancement of 177%.
• Demonstrated stability over 4 weeks and under high-speed centrifugation.
• Thermo-physical properties were dependent on DES composition and GNP concentration.

Conclusions:

• Introduced a new class of surfactant-free graphene nanofluids based on DESs.
• These GNFs exhibit superior thermal conductivity and stability for heat transfer applications.
• The study highlights the tunability of these fluids by adjusting DES and GNP parameters.