Synthesis, characterization and thermal properties of graphene/iron oxide II based hybrid nanofluids for thermal applications: Experimental approach

Fe ₂ O ₃ –GNP (graphene nanoplate) hybrid nanofluids were fabricated, optimized, and evaluated to address the challenge of enhancing thermal conductivity while maintaining stability. The nanofluids were synthesized using a one-step ultrasonication method by dispersing Fe ₂ O ₃ nanoparticles and GNPs in a water–ethylene glycol base fluid. High stability was achieved, as confirmed by zeta potential values above 40 mV and no observable sedimentation over 4  weeks. Optimization was conducted using response surface methodology (RSM). Compared with the base fluid, thermal conductivity and electrical conductivity increased by more than 27% and 440%, respectively, while density and dynamic viscosity increased only by 0.6% and 11%. These findings demonstrate the synergistic effect of Fe ₂ O ₃ and GNP nanoparticles and highlight the novelty and effectiveness of the proposed hybrid nanofluids for high-performance heat transfer applications.