Ammonia capture by MN4 (M=Fe and Ni) clusters embedded in graphene

Capture of hazardous gas molecules is crucial in environmental monitoring, public safety, and industrial chemical processing. In this respect, new strategies for capturing air pollutants are needed. Ammonia (NH3), a corrosive and colorless gas, is one of the most abundant nitrogen-containing compounds in the atmosphere and leads to severe health risks. Inspired by recent research on MN4 clusters (M=Fe and Ni) embedded in graphene (MN(4)G), in this study, the interaction of NH3 with MN(4)G was studied by density functional theory calculations. Our results indicate that the adsorption of NH3 on FeN(4)G is generally stronger than that on the NiN(4)G. The metals can form strong M-N bonds with NH3 and enhance the charge transfer from NH3 to MN(4)G systems. The adsorption energy of NH3 on the FeN(4)G system is significantly increased by introducing extra positive charges into the cluster. Our results indicate that the FeN(4)G nanomaterial is an excellent adsorbent for NH3 capture.