The selective adsorption of formaldehyde and methanol over Al- or Si-decorated graphene oxide: A DFT study

Density functional theory (DFT) calculations are performed to study the adsorption behavior of formaldehyde and methanol on the pristine as well as Al- or Si-decorated graphene oxide (GO). The most stable adsorption configurations, adsorption energies, binding distances and net charge transfers are obtained to understand the impacts of the these molecules on the electronic properties of the pristine or metal-decorated GO surface. The pristine GO exhibits a low sensitivity to both formaldehyde and methanol molecules. However, it is found that the decoration of GO with a Al or Si atom enhances its tendency to adsorb both the above gas molecules. Compared to formaldehyde, methanol is found to have a larger adsorption energy over the decorated GOs, due to the more favorable orbital interaction as well as electrostatic attraction in the resulted complexes. The amounts of charge transfer upon adsorption of formaldehyde and methanol over the Al-decorated GO are larger than those of over the Si-decorated one. Therefore, as a result of interaction with CH₂O and CH₃OH, the electronic properties of the Al-decorated GO change significantly.