A facile and efficient ion sieving system for mono-/mono-valent cations built by using the K+-cross-linked graphene oxide membrane

As an emerging and promising two-dimensional (2D) nanoporous membrane material, the K+-cross-linked graphene oxide membrane composed of 2D K+-controlled nanochannels (abbreviated herein as K+-CLGOM) has recently attracted great attention due to its attractive ion-sieving performance. However, the ion-sieving of K+-CLGOM for mono-/mono-valent cations has been still far from satisfactory. In this work, a facile and efficient ion sieving system for mono-/mono-valent cations was built by using the K+-CLGOM, which was firstly applied to supported a simple model of semi-biomembrane, namely oil/water (O/W) interface. As-obtained voltammetric results demonstrate that K+, NH4+ and Rb+ can prefer over Na+ and Li+ to transfer across K+-CLGOM in the trans-membrane system with O/W interface. This work not only provides the membrane-supported O/W interface as a novel platform to explore and understand the ion discrimination of K+-CLGOM, but also help to further exploit the potential applications of K+-CLGOM in the electrochemical ion sieving and extraction.Graphical abstractSchematic illustration for the preparation process of a K+-CLGOM and the mechanism of cation-pi interaction between K+ and graphene oxide aromatic system.