Two-dimensional Hexagonal Boron Nitride-Ferrofluid Hybrids Enable Efficient Magnetic Cooling

Abstract

Overheating remains a critical limitation in high-performance electronic and computing systems, necessitating the development of efficient thermal management fluids. In this work, a magnetically responsive hybrid ferrofluid was developed by incorporating two-dimensional hexagonal boron nitride (2D-hBN) nanosheets into a Mn-Zn-ferrite-based ferrofluid. The hybrid system retains magnetic responsiveness while leveraging the high in-plane thermal conductivity and chemical stability of 2D-hBN nanosheets. Structural, spectroscopic, and magnetic characterizations confirm the successful incorporation of hBN within the ferrofluid without compromising the magnetic functionality of the ferrite nanoparticles. The thermal conductivity of the hybrid fluid increased from 0.294 to 0.582 W m-1 K-1, representing nearly a twofold enhancement compared to the base ferrofluid. Cooling experiments performed under different magnetic field strengths demonstrate field-dependent thermal performance. At an applied magnetic field of 0.30 Tesla, the hybrid ferrofluid achieved a maximum temperature drop of ~35 °C, corresponding to more than 50% improvement in cooling efficiency compared to the base ferrofluid under identical heat load conditions. These results highlight the potential of 2D-hBN-modified ferrofluids as promising magnetothermal cooling media for passive and magnetically assisted thermal management applications in next-generation electronic systems.