Graphene-assisted Ti3C2 MXene-derived ultrathin sodium titanate for capacitive deionization with excellent rate performance and long cycling stability

Abstract

Sodium titanate (NTO) has limited application in capacitive deionization (CDI) due to its poor conductivity, slow ion deintercalation reaction kinetics, and lattice expansion during charging and discharging. In this work, we design a two-dimensional sodium titanate/graphene (M-NTO/rGO) film material by the solvothermal method, using Ti-MXene as the precursor and graphene as the constraining layer. The ordered two-dimensional structure effectively suppresses interlayer stacking and provides more transmission paths and storage space for Na⁺ ions and electrons. The desalination capacity of M-NTO/rGO can reach 57.57 mg g⁻¹ (30 mA g⁻¹), the desalination rate is 0.019 mg g⁻¹ s⁻¹, and the energy consumption is 0.42 kW h g⁻¹. The NTO derived from Ti-MXene is sandwiched between rGO sheets to maintain a two-dimensional structure, which can alleviate the volume expansion of NTO during charging. After 100 desalination cycles, the desalination capacity remains stable. Therefore, the applied confinement derivation method provides new opportunities for the realization of hybrid materials with two-dimensional ordered structures.