Subsize Ti3C2Tx derived from molten-salt synthesized Ti3AlC2 for enhanced capacitive deionization

Ti3C2Tx is a promising intercalation-type electrode material for capacitive deionization (CDI). However, Ti3C2Tx, obtained from traditional synthesized Ti3AlC2, is with large particle size and undersized interlayer space, which can easily lead to the longer ion diffusion path, fewer adsorption sites, and higher ion diffusion barrier in CDI process. In this work, subsize and Na+ intercalated Ti3C2Tx (Na+-Ti3C2Tx-MS) was prepared by HF etching KCl-assisted molten-salt synthesized Ti3AlC2 and following NaOH treatment. The Na+-Ti3C2Tx-MS achieves a high electrosorption capacity of 14.8 mg/g and a high charge efficiency of 0.81 at the applied voltage of 1.2 V in 100 mg/L NaCl solution. Besides, the stable desalination performance of Na+-Ti3C2Tx-MS has been confirmed. The superior performance of Na+-Ti3C2Tx-MS can be attributed to the subsize particle and larger interlayer space. Both two factors can effectively increase ions adsorption sites, shorten diffusion path lengths, and reduce diffusion barriers in the CDI process.