A comparative theoretical study of CO oxidation reaction by O2 molecule over Al- or Si-decorated graphene oxide

Using density functional theory calculations, the probable CO oxidation reaction mechanisms are investigated over Al- or Si-decorated graphene oxide (GO). The equilibrium geometry and electronic structure of these metal decorated-GOs along with the O2/CO adsorption configurations are studied in detail. The relatively large adsorption energies reveal that both Al and Si atoms can disperse on GO quite stably without clustering problem. Hence, both Al- and Si-decorated GOs are stable enough to be utilized in catalytic oxidation of CO by molecular O2. The two possible reaction pathways proposed for the oxidation of CO with O2 molecule are as follows: O2+CO→CO2+Oads and CO+Oads→CO2. The estimated energy barriers of the first oxidation reaction on Si-decorated GOs, following the Eley-Rideal (ER) reaction, are lower than that on Al-decorated ones. This is most likely due to the larger atomic charge on the Si atom than the Al one, which tends to stabilize the corresponding transition state structure. The results of this study can be useful for better understanding the chemical properties of Al- and Si-decorated GOs, and are valuable for the development of an automobile catalytic converter in order to remove the toxic CO molecule.