Bottom‐Up Synthesis of 2D AlN Nanosheets with Superior Hydrolytic Resistance and Thermal Conductivity

Abstract Advanced electronics require efficient thermal management materials, yet aluminum nitride (AlN) faces critical limitations despite its outstanding thermal conductivity (320 W m ⁻¹ K ⁻¹ ). Conventional spherical AlN suffers from moisture‐induced degradation producing hazardous ammonia gas and requires excessive loading fractions for thermal network formation. Herein, an innovative synthesis strategy producing 2D AlN nanosheets is developed through graphene oxide‐templated chemical deposition followed by carbothermal nitridation. The synthesized 2D AlN features ultrathin architecture (1–2 nm thickness) with remarkable aspect ratios approaching 50. Epoxy composites containing 2D AlN achieve superior thermal performance (5.35 W m ⁻¹ K ⁻¹ at 60 vol.%) compared to spherical AlN systems (3.80 W m ⁻¹ K ⁻¹ ), attributed to enhanced percolation behavior at lower concentrations. Density functional theory calculations reveal quantum size effects elevate nitrogen 2p electronic states, increasing kinetic barriers against hydrolytic attack mechanisms. Under accelerated aging conditions (85 °C, 85% humidity), 2D AlN composites maintain thermal properties with negligible degradation over 200 h. This morphological engineering approach unlocks new possibilities for robust thermal interface applications in demanding electronic environments.