Self-CrosslinkedMXene (Ti 3 C 2 T x )Membranes with Good AntiswellingProperty for Monovalent Metal Ion Exclusion

A 2D membrane-based separation technique has been increasingly applied to solve the problem of fresh water shortage via ion rejection. However, these 2D membranes often suffer from a notorious swelling problem when immersed in solution, resulting in poor rejection for the monovalent metal ion. The design of the antiswelling 2D lamellar membranes has been proved to be a big challenge for highly efficient desalination. Here a kind of self-crosslinked MXene membrane is proposed for ion rejection with an obviously suppressed swelling property, which takes advantage of the hydroxyl terminal groups on the MXene nanosheets by forming Ti–O–Ti bonds between the neighboring nanosheets via the self-crosslinking reaction (−OH + −OH = −O– + H2O) through a facile thermal treatment. The permeation rates of the monovalent metal ions through the self-crosslinked MXene membrane are about two orders of magnitude lower than those through the pristine MXene membrane, which indicates the obviously improved performance of the i...