Binder-free Ti3C2Tx film electrode with chemical-bonded bridge for high-stability hybrid capacitive deionization

Faradic capacitive deionization (CDI) has emerged as an ideal candidate for developing effective water purification from low-concentration desalinated water. However, long-term desalination-stability CDI still faces the challenge in unstable electrode microstructure after hundreds of ion intercalations. Herein, ethylenediaminetetraacetic acid (EDTA)-modified Ti 3 C 2 T x (denoted as EDTA-Ti 3 C 2 T x ) electrodes are proposed through intense chemical interactions without scarifying Ti 3 C 2 T x electronic conductivity, wherein the formed –COO-terminated bridge stabilizes Ti 3 C 2 T x interlayer spacing for strengthening long-term regeneration desalination. Simultaneously, abundant Na + adsorption sites with highly hydrophilic surface in the binder-free high-conductivity EDTA-Ti 3 C 2 T x accelerated ion electro-sorption with efficient ion permeations. Importantly, in 500 mg L −1 NaCl solutions, EDTA-Ti 3 C 2 T x //activated carbon (AC) assembled CDI device delivered an extremely stable adsorption/desorption with salt adsorption-capacity (SAC) retention of 83 % after 500 cycles and a high desalination capacity of 51.0 mg g −1 . In addition, the EDTA-Ti 3 C 2 T x presented without d -spacing changes after 100 cycle desalinations that was significantly different from structural collapse in Ti 3 C 2 T x . This study offers a new idea to overcome poor electrochemical desalination stability via organic molecules stabilized Ti 3 C 2 T x structure.