Understanding the Electrochemistry of Armchair Graphene Nanoribbons Containing Nitrogen and Oxygen Functional Groups: DFT-calculations

The surface and edges chemistry are vital points to assess a specific application of graphene and other carbon nanomaterials. Based on first-principles density functional theory, we investigate twenty-four chemical functional groups containing oxygen and nitrogen atoms anchored to the edges of armchair graphene nanoribbons (AGNRs). Results for band structures, binding energy, band gaps, electronic charge deficit, oxidation energy (EO), reduction energy (ER), and global hydrophilicity index are analyzed. Among the oxygen functional groups, the carbonyl, anhydride, quinone, lactone, phenol, ethyl-ester, carboxyl, α-ester-methyl, and methoxy act as electron-withdrawing groups, conversely, pyrane, pyrone, and ethoxy act as electron-donating groups. In the case of nitrogen-functional groups, the amine, N-p-toluidine, ethylamine, pyridine-N-oxide, pyridone, lactam, and pyridinium transfer electrons to the AGNRs. The nitro, amide, and N-ethylamine act as electron-withdrawing groups. The carbonyl and pyridinium group-AGNR show metallic behavior. The binding energy calculations revealed that lactam, pyridone, pyrone, lactone, and quinone are the most stable structures. Global hydrophilicity index, quinone, and N-ethylamine groups showed the most significant values, suggesting they are highly efficient in accepting electrons from other chemical species. Besides, we discuss the dependence of EO and ER on the ribbon width and nitrogen-doping.