Revealing an Unexpected Chemical Reactivity of Boron Nitride to H 2 O and Alkane Molecules

Herein, substantial experimental evidence reveals the unexpected chemical reactivity of inert hexagonal boron nitride (h-BN) to H2O, CH4, and C2H6 under mild conditions. H2O molecules dissociate at B–N edge sites and insert into the B–N bond even under ambient conditions. Detailed spectroscopic characterization shows this process protonates nitrogen sites and hydroxylates boron sites, forming N–H and B–OH groups. Ultimately, the NH4+ and B(OH)4– ions are released into water as the final products of nitrogen protonation and boron hydroxylation. This reactivity is significantly enhanced at the oxygen-doped B–N edges. Theoretical simulations reveal that strong orbital interactions between the H (1s) orbitals of H2O and the B (2p)/N (2p) orbitals of the B–N edge produce significant chemical stress at the adsorption sites, promoting the dissociation and subsequent insertion of H2O into the B–N bonds. Furthermore, we show that CH4 and C2H6 can be oxidized to CO and trace CH3OH in water over boron nitride at mild temperatures without an additional oxidant. The 18O isotope-tracing experiment confirms that the oxygen in the boron nitride matrix is responsible for the activation and oxidation of the C–H bond of CH4 and C2H6. Simultaneously, the released NH4+ and B(OH)4– ions provide a reaction microenvironment enabling the thermodynamically spontaneous hydration of formed CO to formate. These findings fundamentally challenge the long-standing paradigm of h-BN as a chemically inert material under mild conditions.