Electrolyte‐Replacement‐Free Continuous Electrocatalytic Desalination Coupled With CO ₂ Reduction at Record Throughput and Low Cost

Abstract

ABSTRACT Integrating seawater desalination with electrocatalytic reactions offers an attractive pathway to address freshwater scarcity and reduce emissions simultaneously. However, practical implementation has been impeded by slow desalination, electrolyte degradation, and frequent electrolyte replacement, all of which increase operating costs and limit scalability. Here, we report a continuous electrocatalytic desalination system driven by CO 2 electroreduction that fundamentally eliminates the need for electrolyte replacement via a self‐balancing circulating electrolyte architecture. A five‐chamber cell incorporating a salt‐concentration chamber and an interconnected anolyte–catholyte loop enables sustained ion transport while suppressing byproduct accumulation. Coupled with a highly active nanorod cobalt phthalocyanine/carboxylated carbon nanotube catalyst, the device delivers high current density and stable CO 2 ‐to‐CO conversion. Using natural seawater, the cell achieves an ultrafast salt removal rate of 1592.8 µg cm − 2 min − 1 over 90 h of continuous operation without electrolyte replacement, representing one of the highest values reported for electrocatalytic desalination. Simultaneously, CO production proceeds with a Faradaic efficiency of 95.5%–96.4% and a production rate exceeding 683 µmol cm − 2 h − 1 . The desalinated water reaches potable standards with >99% salt removal, while techno‐economic analysis reveals a drastic reduction in daily electrolyte costs. This work establishes a scalable strategy for high‐throughput, low‐cost desalination integrated with CO 2 valorization.