posted on 2024-03-18, 16:40authored byHugo Cabrera-Tinoco, Luis Borja-Castro, Renato Valencia-Bedregal, Adela Perez-Carreño, Aldo Lalupu-García, Ismael Veliz-Quiñones, Angel Guillermo Bustamante Dominguez, Crispin H. W. Barnes, Luis De Los Santos Valladares
Graphene doped with different transition metals has been
recently
proposed to adsorb CO2 and help reduce the greenhouse effect.
Iron-doped graphene is one of the most promising candidates for this
task, but there is still a lack of full understanding of the adsorption
mechanism. In this work, we analyze the electronic structure, geometry,
and charge redistribution during adsorption of CO2 molecules
by single vacancy iron-doped graphene by DFT calculations using the
general gradient approximation of Perdew, Burke, and Ernzernhof functional
(PBE) and the van der Waals density functional (vdW). To understand
the impact of the pyridinic-N coordination of the iron atom, we gradually
replaced the neighboring carbon atoms by nitrogen atoms. The analysis
indicates that chemisorption and physisorption occur when the molecule
is adsorbed in the side-on and end-on orientation, respectively. Adsorption
is stronger when pyridinic-N coordination increases, and the vdW functional
describes the chemical interactions and adsorption energy differently
in relation to PBE without significant structural changes. The development
of the chemical interactions with the change of coordination in the
system is further investigated in this work with crystal overlap Hamilton
population (COHP) analysis.