Scalable Synthesis of Amine-Grafted Ultrafine Layered Double Hydroxide Nanosheets with Improved Carbon Dioxide Capture Capacity from Air

The development of efficient adsorbents is one of the key technologies for direct air capture (DAC). Herein, a facile and scalable method to synthesize amine-functionalized layered double hydroxides (LDHs) as efficient DAC adsorbents is presented. Specifically, ultrafine and exfoliated Mg2Al–CO3 LDH nanosheets were generated within 2 min via rapid nucleation and aging followed by organic solvent treatment, and they remained exfoliated on the powders after vacuum drying. The well-dispersed LDH nanosheets were grafted with a high density of monolayered aminosilane (5.51 mmol N g–1), leading to a good CO2 adsorption capacity (0.68 mmol g–1) among amine-grafted adsorbents. Additionally, it exhibited good stability with no degradation over 200 adsorption–desorption cycles under ∼20% humid air at 25 °C.