Metal‐Organic Framework Sub‐Nanochannels Formed inside Solid‐State Nanopore with Proton Ultra‐High Selectivity.

Metal‐Organic frameworks (MOFs) have the advantages of high porosity, angstrom‐scale pore size, and unique structure. In this work, a kind of MOFs, UiO‐66 and its derivatives (including aminated UiO‐66‐(NH2)2 and sulfonated UiO‐66‐(NH‐SAG)2), were constructed on the inner surface of solid‐state nanopores for ultra‐selective proton transport. UiO‐66 and UiO‐66‐(NH2)2 nanocrystal particles were in‐situ grown at the orifice of glass nanopores firstly, which were used to investigate the ionic current responses in LiCl and HCl solutions when the monovalent anions (Cl−) were unchanged. Compared with UiO‐66‐modifed nanopores, the aminated MOFs modification (UiO‐66‐(NH2)2) can improve the proton selectivity obviously. However, when the UiO‐66‐(NH‐SAG)2 nanopore is prepared by further post‐modification with sulfo‐acetic acid, lithium ions can hardly pass through the channel, and the interaction between protons and sulfonic acid groups can promote the transport of protons, thus achieving ultra‐high selectivity to protons. This work provides a new way to achieve sub‐nanochannels with high selectivity, which can widely be used in ion separation, sensing and energy conversion. [ABSTRACT FROM AUTHOR]