Comparison of structural, electronic and magnetic properties in nickel-doped graphene containing different pyridinic-N coordination

Recently, single-atom catalysts (SAC) have shown to be an alternative to enable chemical reactions related to the generation of renewable energy and to control environmental pollution. These SACs can be synthesized by modifying the structure of a substrate such as graphene through doping with single transition metal atoms. One of the possible ways to improve its catalytic properties is to modify the coordination of the metal atom with pyridinic-N sites. Thus, understanding the properties of the material when the coordination is modified is crucial for potential applications. In the present work, the electronic, structural and magnetic properties of a graphene sheet doped with a nickel atom were studied by computational simulation using DFT. These properties were inspected by changing the coordination of the nickel atom with pyridinic-N sites. A ∼0.3 eV gap is found when graphene is doped with the nickel atom and it is maintained with the modification of the coordination, except for the substrate with three nitrogen atoms. A change in the chemical nature of the bond between the Ni atom and its neighbours from a pi to a sigma type is also revealed.