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 Ti3C2Tx MXene as the substrate to load Fe3O4 nanoparticles for synthesizing Fe3O4@ Ti3C2Tx heterostructure. In the designed heterostructure, the inner Ti3C2Tx 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 Ti3C2Tx 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 Ti3C2Tx MXene, the obtained Fe3O4@Ti3C2Tx 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@ Ti3C2Tx possesses a strong potential for HCDI applications.