Wave function and molecular reactivity study of char with different edges and the chemisorption properties of nitric oxide

Abstract

Molecular reactivity of simplified char models with armchair and zigzag edges and chemisorption properties of nitric oxide were studied with wave function theory and density functional reactivity theory. By comparing the electronegativity, electrophilicity and nucleophilicity of different models, it was concluded that chemisorptions of nitric oxide onto carbon models were electrophilic reactions. Electrons transferred to nitric oxide during chemisorption processes. The lowest unoccupied molecular orbital (LUMO), the highest occupied molecular orbital (HOMO), value of electron localization function, electrostatic potential distribution on van der Waals surface and electron density difference of char models with armchair and zigzag edges were analyzed. Zigzag edges were packed with more lone pair electrons, making them more vulnerable to electrophilic attacks. Double descriptors of different models were analyzed to elucidate why NO was more inclined to be chemisorbed at edges rather than onto carbon plane. The specific adsorption sites at edges were predicted by comprehensive analyses of atomic charge, condensed local electrophilicity, condensed local softness and the contribution to HOMO/LUMO orbital of each atom. Energies released from NO chemisorptions in different modes were calculated with and without considering London dispersion interaction. The thermodynamic results were consistent with the predictions of wave function theory and density functional reactivity theory. The dispersion effect should be considered when simulating carbon-based material systems.