Carbon Dots-Induced Hydrogen-Bonding Traps in RHO Zeolite: Mechanistic Insights and Superior Flue Gas Separation...

Zeolites stand out as promising materials for flue gas separation, however, it poses a significant challenge to conduct pore interior modifications to improve the separation performance. Herein, we present a novel strategy for constructing hydrogen-bonding traps in a small-pore RHO zeolite by embedding carbon dots (CDs), thereby to regulate pore microenvironment and enhance the separation ability of CO₂/N₂. The incorporation of CDs into the RHO zeolite is realized via a straightforward calcination process, which endows the zeolite with the defect sites rich in hydroxyl groups that easily form hydrogen bonds with CDs. Along with ¹H-¹H DQ-SQ experiments, in situ FTIR and DFT calculations, the unique hydrogen-bonding traps are unraveled, which can selectively capture and concentrate CO₂. As a result, the CDs-containing zeolite (R-500) showcases exceptional performance in terms of both CO₂ adsorption (90.40 cm³ g^-1 at 298K and 1 bar) and CO₂/N₂ (15/85) separation (IAST selectivity of 1063.6). Strikingly, a superior CO₂ adsorption with a capacity of 42.9 cm³ g^-1 is achieved in the dynamic separation process (CO₂/N₂ 15/85). The facile synthesis and impressive separation performance of R-500 provides a promising solution for industrial scale CO₂/N₂ separation in flue gas.