In Situ Monitoring the Molecular Diffusion Process in Graphene Oxide Membranes by ATR-FTIR Spectroscopy

Graphene oxide (GO) membranes have been widely explored for molecular separation, but the molecular diffusion behavior inside GO membranes and the interaction between the diffusates and GO sheets during diffusion is still unclear and rarely studied. In this paper, time-dependent attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy was used for the first time to in situ monitor the diffusion processes of several typical organic solvents through GO membranes. The diffusion coefficients of the solvents and the evolution of molecular interaction during diffusion were investigated. The diffusion coefficients of the solvents decrease with the increase of their interaction with the oxygen-containing functional groups on GO sheets. In addition, when diffusing into GO membranes, solvent molecules exhibit a different aggregation form compared with their bulk states. Time-dependent ATR-FTIR spectroscopy can be an efficient and powerful technique to explore the molecular diffusion mechanism ...