Thermodynamic study of functionalization of graphene oxide with amine nitrogen group by DFT calculations

Graphene oxide (GO) is one of the most important derivatives of graphene, which is formed by adding oxygen groups such as epoxy, hydroxyl, and carboxyl. Functionalization of graphene oxide can be done with different groups, such as oxygen and nitrogen. The agent group selected in this research is the amine group. In this research, we functionalize graphene oxide with amine in two ways. In the first type, we add ammonia on the graphene oxide containing epoxy, which opens the ring and forms graphene oxide functionalized with amine. In the second type, we are dealing with the hydroxyl groups of graphene oxide. By adding ammonia on graphene oxide, graphene oxide is functionalized along with water. Calculations related to both types of functionalization have been performed using the most important branch of computational chemistry, namely the density functional theory method. The selected computational level is B۳LYP, and the basis set is ۶-۳۱G(d,p). For a better review and comparison, calculations have been done in two gas and solvent phases. The quantum mechanical indices calculated in this research include HOMO-LUMO energy, chemical softness and hardness, electrophilicity, and dipole moment. Also, the total electronic energy change of the reactions and the thermodynamic parameters calculated in this activity, including enthalpy (ΔrxnH), entropy (ΔrxnS), and Gibbs free energy (ΔrxnG) changes, have been compared for both reactions in both phases. The results of the calculation of thermodynamic parameters confirm the spontaneous and exothermic functionalization of amine that deals with hydroxyl groups in the solvent phase. Among the applications of graphene oxide functionalized with amine, we can mention the improvement of mechanical properties, increase of absorption capacity, development of nanocomposites, application in drug delivery, development of catalytic materials, and development of batteries and hydrogen fuels.

کلیدواژه ها:

Graphene ، Graphene Oxide ، Functionalized Graphene Oxide ، Amine ، Density Functional Theory