Paradigm-shifting carbon capture with high efficiency and net-negativity through bio-inspired oceanic mineralization

초록

Carbon removal is essential for combating ocean acidification and global warming caused by anthropogenic carbon emissions. However, existing carbon capture technologies face energy and sustainability challenges. Amine-functionalized sorbents for direct air capture (DAC) suffer from high regeneration temperatures and humidity sensitivity, whereas ocean alkalinity enhancement (OAE) risks localized pH spikes and the runaway mineralization. Inspired by marine invertebrates that spatially confine chemical microenvironments for shell formation, we develop a hydrogel platform integrating hydrolyzable amines and calcium-binding carboxylates. Controlled hydrolysis releases alkalinity in stoichiometric synchrony with localized Ca2+ enrichment, driving aragonite precipitation at the gel-seawater interface. The hydrogel sequesters up to 2.85 mmol CO2 g-1, outperforming state-of-the-art DAC benchmarks like amine-functionalized covalent organic frameworks (COFs, 2.05 mmol CO2 g-1). By bypassing the thermal CO2 regeneration and gas compression cycles required in DAC, this platform achieves a net-negative carbon balance of up to -0.198 kg CO2 eq. kg-1 when utilizing biogenic precursors, without relying on renewable energy. Furthermore, the hydrogel demonstrates recyclability through the facile replenishment of renewable amines, coupled with mechanical robustness to withstand repeated detachment and reuse. Consequently, this study validates renewable nitrogen feedstocks as a highly feasible pathway for scalable carbon removal and high-value aragonite recovery.

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