This review provides exhaustive insights into material and process design of adsorption-based direct air capture in the past five years.

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 Mg 2 Al−CO 3 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 CO 2 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.

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