Solid
adsorbents with high NH3 separation performance
and good stability are particularly important for industrial applications.
In our work, few-layered hexagonal boron nitrides (h-BNs) were synthesized
and proposed as a kind of solid adsorbent by utilizing the abundant
Lewis acidic B atoms on h-BNs. The synthesized h-BNs were investigated
for NH3 separation both experimentally and theoretically.
It is found that the NH3 isotherms of h-BNs slightly deviate
from the ideal profiles, suggesting that the h-BNs enable moderate
interactions with NH3. At the pressure of 0.1 and 1 bar,
the h-BNs can adsorb as much as 2.33 and 8.67 mmol/g of NH3, respectively. The h-BNs also demonstrate highly selective adsorption
of NH3 from other gases such as N2, H2, and CO2, regardless of calculated ideal selectivities
or breakthrough adsorption of mixed gases. The NH3 adsorption
of h-BNs can be completely reversed, and the h-BNs also exhibit high
oxidative resistance, which is of vital importance for the long-term
application in industry. Density functional theory calculations and
molecular dynamics simulations were further conducted to rationalize
the effective separation of NH3 by h-BNs and disclose the
underlying mechanism at the molecular level.