Hydrophobic ZIF-8 covered active carbon for CO2 capture from humid gas

The performance of activated carbon (AC) will be severely affected for carbon dioxide (CO 2 ) capture in flue gas, as they usually suffer from competitive adsorption of water vapor. Establishment of a barrier against moisture on the surface of porous adsorbent material could potentially address this issue. Zeolite-like metal–organic frameworks (ZIF-8) as a promising adsorbent material demonstrates hydrophobic properties, large specific surface area, and highly porous structure. Here, by further growth of ZIF-8 on polydopamine (PDA)-coated bio-based carbon (AC@PDA), we fabricate hydrophobic final product (AC@ZIF-8). The CO 2 capture capacities of AC@ZIF-8 was 41.69 cm 3 /g, which is only 13.61% lower than that of the initial AC under dry conditions. The hydrophobic ZIF-8 layer can effectively prevent water molecules from reaching the interior AC. Therefore, the adsorption of CO 2 for AC@ZIF-8 decreased by only 16.74% under high relative humidity, while it decreased by 61.27% for bare AC. This strategy will broaden the applications of carbon-based adsorbents for CO 2 capture under severely humid conditions. We believe that this approach is also applicable for an extensive set of CO 2 capture materials that suffer from water instability.