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

Abstract

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.

Converting Nanoflower-like Layered Double Hydroxides into Solvent-Free Nanofluids for CO2 Capture

“…The chemical composition of LDHs is usually [M 1– x 2+ M 3+ x (OH) 2 ] x + ·[A x /n n– ·mH 2 O] x ‑ , where M is the metal ion, A n– represents the interlayer anion, x refers to the substance ratio of M 2+ /(M 2+ +M 3+ ), and m is the number of interlayer water molecules. , The main laminate is covalently bonded between atoms, while the interlayer is weakly interacted, such as hydrogen bonding, ionic bonding, etc. Furthermore, the flexibility and versatility of LDHs’ layered crystal structure have made them receive extensive concern in adsorption, − catalysis, , anticorrosion, , energy storage, , etc. Notably, LDH nanosheets (LDH-NSs) have a wide distribution of active sites on their surfaces .…”