Supramolecular Calix[]arenes-Intercalated Graphene Oxide Membranes for Efficient Proton Conduction.

Graphene oxide (GO) membranes with 2D interlaminar channels have triggered intensive interest as ion conductors. Incorporating abundant ion-conducting sites into GO interlayers is recognized as an effective strategy to facilitate ion conduction. Herein, we designed supramolecular compounds, -sulphonato-calix[]arenes (-SC[]As), as versatile intercalators to acquire highly conductive and robust GO membranes. The SC[]A with ultrahigh ionic exchange capacity (IEC, 5.37 mmol g) imparts sufficient proton donors, and its rigid framework imparts strong support of adjacent nanosheets. We designed three kinds of SC[]As with the same IEC but different sizes as intercalators, endowing the GO/SC[]A membranes with increasing ion concentration and -spacing in the order of GO/SC[4]A < GO/SC[6]A < GO/SC[8]A. Therefore, the interlayers of GO/SC[8]A membranes afforded higher density of proton donors and could accommodate more water molecules to construct more continuous H-bond networks for proton transfer. Accordingly, the proton conductivities exhibited the same increasing trend, up to 327.0 mS cm of GO/SC[8]A-30% at 80 °C, 100% RH, which was 2.80 times higher than that of the GO membrane. Moreover, the GO/SC[]A membranes remained stable in wet state, along with a 66% elevation in mechanical performance compared to the GO membrane.