CNTs-enabled enhanced capacitive deionization desalination: From material innovation to electrode optimization and device integration

Capacitive deionization (CDI), as an emerging desalination technique, has been intensively explored because of its energy-saving, cost-effectiveness and sustainability. Despite the promise, CDI systems still encounter various challenges involving active sites, mass transfer and stability that severely limit their further application. So far, there is still much-limited review across material, electrodes and devices to cope with the above challenges. Notably, carbon nanotubes (CNTs), have garnered significant attention owing to their exceptional conductivity, high specific surface area (S_BET), unique skeleton role and superior mechanical strength. More importantly, CNTs serve multifunctional roles in CDI systems, including active materials, conductive agents, binders, and even current collectors, while also making for the thick electrode framework construction. Specifically, this review first discusses current challenges in CDI system design. Subsequently, it systemic highlights how CNTs address these issues through material innovation, electrode optimization and device integration. Eventually, a conceptual model for CNT composite self-supporting CDI systems is further proposed, aiming to exploit advanced CDI desalination systems. Overall, this review underscores the pivotal role of CNTs in overcoming technical bottlenecks and driving the practical application of CDI for sustainable water treatment.