Emerging MXene-based electrode materials for efficient capacitive deionization: A comprehensive review

Capacitive deionization (CDI) has been considered a potential desalination technology because of its simple operation, high repeatability and low energy consumption. It is well known that electrode materials play a crucial role in the performance of CDI. As an emerging two-dimensional material, MXene have shown great application potential in CDI due to the unique two-dimensional structure, abundant surface functional groups and excellent physicochemical properties. In order to further improve the desalination performance of CDI, MXene-based electrode materials have received extensive attention and research. In this review, the structure, properties and synthesis strategies of MXene are analyzed to clarify the relationship between properties and desalination performance. The excellent electrical conductivity, mechanical property and hydrophilicity of MXene lay the foundation for the efficient desalination of MXene-based electrode materials. Then, the latest advance of MXene-based electrode materials in CDI is summarized. The optimization strategies of MXene-based materials include surface functional group regulation, in situ derivation and heterostructure construction. Finally, the current challenges and future prospects are presented from the perspectives of novel MXene-based CDI system, desalination mechanism, CDI battery and real water environment, which provides new inspiration and insight for the further development of CDI.