High‐Performance Electrochemical Chloride Ion Storage with Hierarchical Ternary Metal Hydroxides for Sustainable Water Purification

Abstract The increasing demand for clean water and renewable energy drives the need for efficient chloride ion removal from saline water. Here, we present a membrane‐free flow‐through electrochemical system using hierarchical FeCoNi‐layered triple hydroxide nanosheets grown directly on porous nickel foam (FeCoNi‐LTH/NF). The ternary composition uniquely enhances chloride ion adsorption by modulating electronic structure and ion binding energy. The in situ electrode synthesis approach ensures direct, binder‐free contact, enhancing charge transfer and ion storage. Consequently, the FeCoNi‐LTH/NF electrode achieves outstanding chloride removal capacity (180.07 mg g −1 ), rapid adsorption rates, high energy efficiency, and exceptional stability (100% capacity retention after 1000 cycles). This work demonstrates the potential of a hierarchical triple hydroxide electrode as a scalable, cost‐effective, and energy‐efficient solution for sustainable water purification.