High-Quality Boron Nitride Nanosheets and Their Bioinspired Thermally Conductive Papers

Hexagonal boron nitride has displayed increased potential in heat dissipation applications due to its desirable high thermal conductivity and remarkable thermal stability. However, the large-yield and high-quality preparation of boron nitride nanosheets (BNNSs) has been still an enormous challenge. In present work, we developed a universal exfoliation strategy to synthesize few-layer and defect-free BNNSs, which involved the intercalation of hexafluorosilicates/sodium hydroxide into BN crystals followed by exfoliation through a mild stirring process. The yield and concentration of as-obtained BNNS reached up to 78.5% and 12.78 mg/mL, respectively. More importantly, this method has been proven to exfoliate other layered materials like graphene (G), MoS₂, and WS₂. These as-obtained BNNSs can be directly used for constructing freestanding papers with high thermal conductivities. Typically, the thermal conductivities of the BNNS-G hybrid paper were up to 63.5 W/mK along the in-plane direction and 7.4 W/mK along the through-plane direction. According to the thermal interface materials performance measures, BNNS-G hybrid paper shows great promising applications for heat transfer in integrated circuit packaging.