Adsorption of ammonium on a pyridine-like nitrogen-doped graphene layer decorated with a monovalent atom

Density functional theory and molecular dynamics were used to study the interaction of an NH$_{4}$ molecule with a pyridine-like nitrogen-doped (PNG) surface. The surface is decorated with an impurity taken from the first row of the periodic table. In this way, we considered six different atoms: H, Li, Na, K, Rb and Cs, to decorate the system. We found two final configurations. One, is with the NH$_{4}$ molecule physisorbed around the impurity. In the second situation, one hydrogen atom of the ammonium molecule, is adsorbed around a nitrogen atom of the surface. The remaining NH$_{3}$ molecule stays physisorbed on the system. The final configuration depends on the initial position of the NH$_{4}$ molecule. In all decoration cases, the system was allowed to follow an evolutionary process using molecular dynamics at 300 K, and atmospheric pressure.