Effect of co-adsorption of small molecules in air on property of penta-graphene and their proton transfer calculation

Penta-graphene has attracted considerable attention due to its unique structure and novel properties. Herein, we studied the effect of the co-adsorption of small molecules from air on the properties of penta-graphene using first-principles calculations. Our results show that oxygen molecules can be self-decomposed on the surface of penta-graphene and the process of O2 decomposition is an exothermic reaction. On the contrary, the adsorption of H2O or N2 molecule on penta-graphene exhibits weak interaction characteristic. For co-adsorption systems, the adsorption of N2 molecule has no effect on the electronic properties of penta-graphene because the N2 molecule is more inert than other molecules. Hydrogen bonds (H-bonds) have been observed in the co-adsorption of H2O and O2 on penta-graphene. We find that shorter H-bonds lead to higher stability of the systems. We also explore the proton transfer process between H2O and oxidized penta-graphene. Our results show that the proton transfer process is relatively difficult due to the high energy barrier. However, double-proton transfer is an exothermic process since the energy of the final state is 0.11 eV lower than that of the initial state. These results indicate that the configuration of oxidized penta-graphene is complicated. Our research provides a theoretical basis and important guidance for the experimental synthesis and functionalization of penta-graphene.