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

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 Ca²⁺/CO₃ ^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 cm² 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 CO₂ and a cost of $139 t^-1 CO₂. Extending beyond CaCO₃, we precipitate additional sparingly soluble phases (CaF₂, BaSO₄, PbSO₄) 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.