From a potential application point of view, it is important to understand the water transport in graphene-based nanochannels with impurities. For example, GOMs exhibit promising membrane properties . The two key parameters for using GOMs as water purification membranes are first, their capability to reject certain solutes and, secondly, letting pass as much solvent as possible . The recent advance in controlling the interlayer space of GOMs via intercalation of cations is a promising approach to tune the porosity . With that potentially controlling the rejection of dissolved ions in aqueous solution using GOMs . Here, the intercalation of K + prevents swelling of GOMs in a wet environment . Without control, swelling leads to an increase in interlayer space and hence an increase in pore size of the GOMs. Intercalation with K + prevents swelling and reduces the interlayer space of wet GOMs, allowing the rejection of smaller species . Higher cation concentration led to even lower interlayer space of wet GOMs 17 . The cation intercalated GOMs exhibit various performance improvements, including long-term aqueous stability and strength, and excellent molecular separation performance .