DFT-based theoretical simulation on electronic transition for graphene oxides in solvent media

Abstract

Electron absorption spectra of graphene oxide (GO) nanosheets in solvents could provide a unique measure of the GO-solvent interaction, which is also important to the GOs-based optoelectronic and photocatalytic applications. In this work, the effects of solvent polarity and solvent-GO hydrogen bonding (HB) interaction on the electron absorption for GO nanosheets in liquid-phase solvents have been investigated by density functional theory. At first, we adopted various types of implicit solvent modes to study the polarity influence on the GO absorption spectra, including non-polar and polar solvents. Then, two representative explicit solvent molecules (NMP and water) have been considered to study the effect of HB interaction on the electronic excitation of GOs. The natural transition orbital (NTO) analysis elucidates that the hole-electron pair transition mechanism for GO electronic excitation is mainly featured by the charge transfer over GO surfaces. The solvatochromic effects were further elucidated by the correlation of the typical excitation energies with the solvent-induced GO dipole and the HB strength. The simulation results provide a new understanding of the influence of solvents on the electronic excitation of nanoscale GOs.