Elucidation of the pore structure of graphene oxide (GO) is crucial to understand the promising interfacial properties. Measuring gas adsorption isotherms is the standard method for evaluation of porous solids, which usually employs a vacuum pre-treatment above 373 K. As GO is thermally unstable, we demonstrated that the pre-evacuation of freeze-dried GO at 1 Pa and 298 K for 24 h successfully removed adsorbed water without changing the initial structure. Subsequently, a multiprobe gas adsorption analysis using N-2, Ar, O-2 and H2O was applied for clarification of GO nanoporosity. GO has quite narrow necked pore entrances susceptible to pore-blocking effect. The adsorption amounts of non-polar probes were very small, giving the minimum and maximum BET surface areas with N-2 (largest quadrupole moment) and O-2 (smallest MIN-2 size), respectively. Oppositely, H2O strongly interacts with the functional groups at pores entrances leading to their opening and exposition of the potential porosity.
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