MXene‐Based Capacitive Deionization–Strong Competitor Among Faradaic Electrode Systems: Current Status and Future Perspectives

Abstract

Capacitive deionization (CDI) of brackish water is emerging as a sustainable and energy efficient desalination processes to mitigate the excessive demand of freshwater. Despite that the porous carbon is prime choice in the conventional CDI; its electrostatic interaction‐based limited salt adsorption capacity (SAC, up to 25 mg g−1) has driven the research interest to explore various Faradaic electrodes for attaining maximum SAC (>100 mg g−1) in supplementation with the other desalination metrics. MXene is one of the newly discovered intercalation‐type pseudocapacitive nanostructures, which promised an excellent desalination performance due to its intriguing properties, such as tuneable interlayer spacing, high electrical conductivity, hydrophilicity, and structural integrity. Furthermore, its compositing/heterostructuring with other electro‐active components significantly improves the desalination activity. This article provides a systematic overview of the MXene‐based electrodes utilized in CDI along with the one‐to‐one comparison with other Faradaic systems. Materials design, structure, cell architecture, desalination metrics‐based performance evaluation, and underlying driving forces behind the salty ions removal activity are the main emphasis of discussion to realize MXene‐based efficient CDI desalination. Lastly, the key issues and perspectives of MXene‐based electrode systems are put forward towards new developments and real time implication.