Self‐Biased Electro‐Mineralization via Programmable Field Engineering for Energy‐Efficient Ocean Carbon Removal

ABSTRACT Gigaton‐scale carbon removal demands geologic permanence at low land, water, and energy cost. Ocean pathways are promising, but many electrochemical routes require large pH swings, membranes/sorbents, and suffer from fouling. We report the self‐biased electro‐mineralization as a practical route to ocean carbon removal. Porous core‐shell electrodes program interfacial fields that direct Ca 2+ /CO 3 2− transport and trigger in‐pore crystallization in simulated seawater, without membrane stacks or large bulk pH swings. Field strength is tunable via core/shell ratio, polymer chemistry, and fixed‐charge density, enabling the architecture to deliver long‐duration, fouling‐resistant operation (>2000 h), ∼25% DIC conversion under flow. A 400 cm 2 cell and a simple 100‐liter stirred reactor show that the microscale, uniform field both preserves performance under geometry area scale‐up and enables low‐overhead capacity expansion. Techno‐economic analysis projects an energy consumption of 44 kJ mol −1 CO 2 and a cost of 139 t −1 CO 2. Extending beyond CaCO 3, we precipitate additional sparingly soluble phases (CaF 2, BaSO 4, PbSO 4) from complex brines, establishing a platform also supporting resource recovery. These results shift ocean mineralization from bulk‐solution manipulation to programmable reaction‐environment design, advancing a scalable, cost‐effective pathway to climate relevant carbon removal.