A comparative DFT study on the CO oxidation reaction over Al- and Ge-embedded graphene as efficient metal-free catalysts

• Published in: Applied surface science 2016-08, Vol.378, p.418-425
• Main Authors: Esrafili, Mehdi D., Nematollahi, Parisa, Abdollahpour, Hadi
• Format: Article
• Language: English
• Subjects: Al-embedded graphene; Aluminum; Atomic radius; Catalysts; CO oxidation reaction; DFT; ER mechanism; Ge-embedded graphene; Germanium; Graphene; LH mechanism; Mathematical analysis; Oxidation; Surface chemistry
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2016.04.012

[Display omitted] •The oxidation of CO by O2 molecule is investigated over Al- and Ge-embedded graphene.•The first reaction pathway of the CO oxidation over both surfaces should proceed with the ER mechanism.•Ge-embedded graphene can be used as a more efficient catalyst for oxidation of CO than Al- embedded graphene. In the present study, by means of density functional theory (DFT) calculations, the catalytic oxidation of CO by O2 molecule is investigated over Al- and Ge-embedded graphene. The large atomic radius of these dopant atoms can induce a local surface curvature and modulate the electronic structure properties of the graphene sheet through the charge redistribution. It is found that the adsorption of molecular O2 over Al- or Ge-embedded graphene is stronger than that of CO molecule. The CO oxidation reaction by molecular O2 on Al- and Ge-embedded graphene is comparably studied. The results indicate that a two-step process can occur, namely, CO+O2→CO2+Oads and CO+Oads→CO2. Furthermore, the computed activation energy (Eact) for the first reaction on Ge-doped graphene is lower than that of Al-doped one, and the formation of second CO2 molecule on both surfaces can occur rapidly due to its low energy barrier (0.1eV).