Electrolytic Mineralization of CO2

Abstract Natural rock weathering has the potential to store approximately 10⁵ gigatons of CO₂ as solid carbonates.¹,² However, the conversion of silicates and CO₂ into carbonates is slow, resulting in the mineralization of merely 0.13 gigatons of CO₂ each year.¹ Here, we demonstrate a continuous flow electrochemical reactor capable of capturing and permanently storing CO₂ in the form of inert carbonate minerals. This “weathering electrolyzer” accelerates rock weathering by up to 3 orders of magnitude by electrolytically generating H⁺ and OH– in chambers separated by a Ca²⁺-selective membrane. The H⁺ decomposes silicates into reactive Ca²⁺ species in a chemical chamber, while the OH– reacts with CO₂ and Ca²⁺ to form CaCO₃ mineral in an adjacent cathode compartment. We show that the weathering electrolyzer is capable of mineralizing CO₂ derived from both flue gas and air, while avoiding the need to isolate CO₂ from conventional capture units.