Surfactant-functionalized cation-conductive electrode for scalable electrochemical ion pump desalination

The global challenge of freshwater scarcity has intensified the demand for efficient desalination technologies. Electrochemical ion pumping (EIP) represents an emerging desalination approach that enables continuous ion separation with minimal energy loss. However, current EIP designs rely heavily on structurally intricate electrode assemblies and costly ion-exchange polymers, which together hinder practical deployment. In this study, we propose a simple and scalable fabrication strategy for cation-conductive electrodes (CCE) by in situ anchoring sodium dodecyl sulfate (SDS) onto activated carbon (AC) via hydrophobic adsorption, followed by stabilizing the functionalized carbon within a cross-linked polyvinyl alcohol (PVA) network. The hydrophobic interaction ensures stable attachment of SDS, while the hydrogel network further secures the functionalized carbon within the electrode matrix. This integrated design eliminates the need for separate ion-exchange polymer layers and simplifies the electrode architecture by combining charge functionality and structural support within carbon electrode framework. Structural and surface analyses confirmed the successful introduction of sulfonate groups, leading to increased surface negativity and improved ion accessibility. The optimized electrode achieved an ion flux of 0.09 μmol cm^-2 min^-1 with a specific energy consumption as low as 0.33 J μmol^-1, while maintaining a charge efficiency of 73.4 % during continuous desalination. Scaling-up experiments using multi-electrode stacks demonstrated stable performance and practical applicability. This work provides a simple and effective strategy for fabricating high-performance ion-conductive electrodes, advancing the development of EIP toward efficient and scalable desalination.