Adsorption of Hydrogen Cyanide, Cyanogen Fluoride and Cyanogen Chloride on Iron Decorated Graphene Substrates: A DFT-D2 Study

The widespread and frequent use of hydrogen cyanide (HCN), cyanogen fluoride (FCN) and cyanogen chloride (CNCl) in commercial scenarios is causing harm to the environment and all living beings. This study explores the adsorption properties of HCN, FCN, and CNCl on various types of graphene, including pristine graphene (PG), graphene with mono-vacancies (MVG), and graphene doped with pyridine-like nitrogen (PNG), using density functional theory (DFT). The parallel and perpendicular modes are used for the interaction of adsorbate over the adsorbent. It is found that the HCN/FCN/CNCl shows favourable physisorption over the PG/MVG/PNG with a small adsorption energy and minimal charge transfer. In this case, there is no formation of direct bonds between the adsorbate and the adsorbent. This computational work also investigates the adsorption capacity of Fe-MVG and Fe-PNG to hazardous gases HCN, FCN and CNCl along with their structural properties like bond length, bond order and electronic properties such as density of state, partial density of state, band gap and electron density deference plot. The adsorption capacity of intrinsic graphene can be improved by introducing defects and doping with iron (Fe) metal atoms.