Molten salt etching synthesis of Ti3C2Tx/Ni composites for highly efficient capacitive deionization

Capacitive deionization (CDI) has garnered significant attention as a promising solution to address the issue of freshwater scarcity. Developing novel electrodes with high salt removal capacity and good stability is crucial for the high-performance CDI devices. In this study, Ti3AlC2 is employed as a precursor to prepare Ti3C2Tx/Ni composite for the CDI anode and cathode using the molten salt etching method. The Ti3C2Tx/Ni composite exhibits a well-preserved accordion-like morphology of Ti3C2Tx, with Ni nanoparticles uniformly distributed on the surface and between layers. The Ti3C2Tx/Ni composite possesses a large interlayer spacing and high specific surface area, which can effectively trap Cl− and Na+ ions. Moreover, the Ti3C2Tx/Ni interface can improve electronic conductivity and enhance ion transport. As a result, the Ti3C2Tx/NiǁTi3C2Tx/Ni CDI symmetry device exhibits a salt removal capacity of 49.4 mg g−1 in a 500 μS cm−1 NaCl solution at an applied voltage of 1.2 V with a removal rate of 3.00 mg g−1 min−1. After 30 cycles, the Ti3C2Tx surface remains unoxidized, and the salt removal capacity increases, indicating that the surface functional groups (−Cl and −O) and Ni nanoparticles can alleviate oxidation and facilitate the cycle stability of the Ti3C2Tx/Ni composites.