In situ constructed Ti₃C₂T_x MXene/polypyrrole composite with enhanced sodium storage capacity for efficient hybrid capacitive deionization

Two-dimensional layered material Ti₃C₂T_x MXene is considered an excellent capacitive deionization (CDI) electrode material due to its two-dimensional structure and high conductivity. However, the self-stacking of MXene limits its structural stability and effective ion accommodation in CDI field. In this work, Ti₃C₂T_x MXene/polypyrrole (PPy) is synthesized by in situ polymerization of conductive PPy on the surface of Ti₃C₂T_x MXene nanosheets. The hybrid not only effectively alleviates the self-stacking of MXene to improve the structure stability, but also combines the high conductivity of MXene and the excellent electrochemical capacity of PPy. Therefore, when used as HCDI electrode, Ti₃C₂T_x MXene/PPy displays an excellent desalination performance including a high desalination capacity of 50.64 mg g⁻¹, a superior desalination rate of 16.5 mg g⁻¹ min⁻¹ and excellent cycling stability. Ti₃C₂T_x/PPy should be a very promising electrode material for highly efficient desalination.