Fe–Porphyrin-like Nanostructures for Selective Ammonia Capture under Humid Conditions

We performed a computational search for selective NH3 capture of metal–porphyrin-like graphenes using first-principles density functional theory calculations. Using equilibrium thermodynamics parametrized by the first-principles calculations, we found that NH3 molecules can be selectively adsorbed on a metal atom at room temperature and low pressure while immersed in gas mixtures of NH3 and H2O even. In addition, they could be released at a temperature increase of 150 K. We identified that the optimal candidate for selective NH3 capture under humid conditions was Fe–porphyrin-like graphene, reaching a working capacity of ∼4 mmol/g at ambient conditions. We also found that Fe–porphyrin-like carbon nanotubes selectively captured NH3 under humidity conditions. This study allows us to discover novel promising Fe-anchored carbon materials for the selective capture of ammonia from humid air at ambient temperature and pressure conditions.