Graphene-facilitated synthesized vertically aligned hexagonal boron nitride nanowalls and their gas adsorption properties.

The capability of hexagonal boron nitride (h-BN) to adsorb gas atoms may stimulate various promising applications in environment remediation and energy storage, while the interactivity with gas molecules yet remains challenging due to its inherent chemical inertness. In this article, we report a feasible and effective route for the scalable synthesis of vertically aligned h-BN nanowalls assisted by reduced graphene oxide (rGO) without metallic catalysts. The average thickness of the fine h-BN nanowalls is few-atomic layers about 3.7 nm, that grow on the large substrate-like flakes transformed from the pristine rGO. The hierarchical h-BN nanowalls exhibit an enhanced gas adsorption performance, not only through physisorption owing to the synergistic combination of different porous geometries, but also through chemisorption via the open edge groups. Moreover, it demonstrates a significantly enhanced adsorption of CO2 over CH4 as compared to the h-BN nanosheets with similar sizes. Density functional theory calculations reveal that the -OH edge groups can effectively increase the adsorption capability towards CO2, accompanied by a shortened adsorption distance when the gas molecule is energetically stabilized. The wetting characteristics of h-BN nanowalls was further examined by contact angle goniometry.