Facile fabrication of intercalation-type pseudocapacitive S-Ti3C2Tx/PANI/F-Ti3C2Tx cathode for asymmetric capacitive deionization

Abstract

Although tremendous efforts have been paid on Ti3C2Tx as a cathode for capacitive deionization (CDI), its structural instability and easy agglomeration have always limited such a promising application. In this study, a hybrid of hollow Ti3C2Tx spheres and flakes was synchronously fabricated by a novel sacrificial-templated method for the first time, and then immobilized/bonded together by in-situ polymerization of polyaniline, which was labelled as S-Ti3C2Tx/PANI/F-Ti3C2Tx. The highest specific capacitance of S-Ti3C2Tx/PANI/F-Ti3C2Tx in 1 M NaCl solution was measured to be 102 F·g−1, and diffusion capacitance of the as-obtained S-Ti3C2Tx/PANI/F-Ti3C2Tx was calculated to be 63%. Thus, a high salt adsorption capacity of 76 mg·g−1 with a maximum salt adsorption rate of 11.45 mg·g−1·min−1 was obtained, which is much higher than that of Ti3C2Tx-related materials in literature for asymmetric CDI system. Moreover, such a superior desalination performance was verified stable at almost 100% after 30 cycles. Besides the ion intercalation and fluoro/hydroxyl groups of Ti3C2Tx, the high performance and stability of the as-obtained S-Ti3C2Tx/PANI/F-Ti3C2Tx should also be ascribed to the beneficial effects of immobilization/bonding role of conductive PANI between S-Ti3C2Tx and F-Ti3C2Tx. This study gives a new perspective to promote the real applications of CDI by designing highly capacitive and stable electrode materials.