PNNL

Abstract

The interfacial region of the graphene oxide (GO)-water system is non homogenous due to the presence of two distinct domains: an oxygen rich surface and a graphene like region. The experimental vibrational sum frequency generation (vSFG) spectra are distinctly different for the fully oxidized GO-water interface as compared to the reduced GO-water case. Computational investigations using ab initio molecular dynamics were carried out to determine the molecular origins of the different spectroscopic features. The simulations were first validated by comparing the simulated vSFG spectra to experiment and the contributions to the spectra from different hydrogen bonding environments and interfacial water orientations were determined as a function of the oxidation level of the GO sheet. The ab initio simulations also revealed the reactive nature of the GO-water interface.