Tunable, Multifunctional Ceramic Composites via Intercalation of Fused Graphene Boron Nitride Nanosheets.

Abstract

Ternary two-dimensional (2D) materials such as fused graphene-boron nitride (GBN) nanosheets exhibit attractive physical and tunable properties far beyond their parent structures. Although these features impart several multifunctional properties in various matrices, a fundamental understanding on the nature of the interfacial interactions of these ternary 2D materials with host matrices and the role of their individual components has been elusive. Herein, we focus on intercalated GBN/ceramic composites as a model system and perform a series of density functional theory calculations to fill this knowledge gap. Propelled by more polarity and negative Gibbs free energy, our results demonstrate that GBN is more water-soluble than graphene and hexagonal boron nitride (h-BN), making it a preferred choice for slurry preparation and resultant intercalations. Further, a chief attribute of the intercalated GBN/ceramic is the formation of covalent C-O and B-O bonds between the two structures, changing the hybridization of GBN from sp2 to sp3. This change, combined with the electron release in the vicinity of the interfacial regions, leads to several nonintuitive mechanical and electrical alterations of the composite such as exhibiting higher young's modulus, strength, and ductility as well as sharp decline in the band gap. As a limiting case, though both tobermorite ceramic and h-BN are wide band gap materials, their intercalated composite becomes a p-type semiconductor, contrary to intuition. These multifunctional features, along with our fundamental electronic descriptions of the origin of property change, provide key guidelines for synthesizing next generation of multifunctional bilayer ceramics with remarkable properties on demand.