Ferroferric oxide@titanium carbide MXene heterostructure with enhanced sodium storage ability for efficient hybrid capacitive deionization

Exploring novel materials with excellent desalination capacity and cycling ability is essential in designing high performance hybrid capacitive deionization (HCDI). Fe₃O₄ enjoys high electrochemical performance, but due to its easy aggregation and poor electrical conductivity, its desalination performance has been severely restricted. In this work, we employed Ti₃C₂T_x MXene as the substrate to load Fe₃O₄ nanoparticles for synthesizing Fe₃O₄@ Ti₃C₂T_x heterostructure. In the designed heterostructure, the inner Ti₃C₂T_x MXene not only works as the conductive substrate for improved electron transfer, but also supplies plentiful sites for the direct growth of uniform Fe₃O₄ nanoparticles. Moreover, the Fe₃O₄ nanoparticles coated on Ti₃C₂T_x MXene could further protect the agglomeration and self-oxidization of MXene. Owing to the novel structural advantages as well as synergistic sodium storage ability from pseudocapacitive Fe₃O₄ and Ti₃C₂T_x MXene, the obtained Fe₃O₄@Ti₃C₂T_x heterostructure exhibits a remarkable desalination capacity of 44 mg g⁻¹ and superior cycling performance over 40 cycles without obvious capacity fading, indicating that Fe₃O₄@ Ti₃C₂T_x possesses a strong potential for HCDI applications.