MOF-derived bimetallic coordination polymer@cobalt-aluminum layered double hydroxide for highly selective CO2 adsorption: Experiments, mechanisms

• A novel adsorbent (Co-Al-LDH@Hf/Ti-MCP-AS) was prepared by MOF derivatization for the adsorption of CO 2 . • The novel adsorbent shows a very high selective adsorption capacity and reusability for CO 2 . • Thru XPS characterization and DFT computational verification, it is shown that the adsorption mechanism is mainly CO 2 -producing carbamate by acid-base action with adsorbents. Selective capture of CO 2 is one of the most effective strategies for combating the greenhouse effect. In this study, we report the synthesis of a novel adsorbent—an amine-based cobalt-aluminum layered hydroxide with a hafnium/titanium metal coordination polymer (denoted as Co-Al-LDH@Hf/Ti-MCP-AS)—through the derivatization of metal–organic frameworks (MOFs) for selective CO 2 adsorption and separation. Co-Al-LDH@Hf/Ti-MCP-AS achieved the maximum CO 2 adsorption capacity of 2.57 mmol g −1 at 25 °C and 0.1 MPa. The adsorption behavior followed the pseudo-second-order kinetics and Freundlich isotherm models, indicating that chemisorption occurs on a non-homogeneous surface. Co-Al-LDH@Hf/Ti-MCP-AS also exhibited selective CO 2 adsorption in CO 2 /N 2 and excellent stability over six adsorption–desorption cycles. An in-depth analysis of the adsorption mechanism through X-ray photoelectron spectroscopy and density-functional theory and frontier molecular orbital calculations revealed that adsorption occurs through acid–base interactions between amine functional groups and CO 2 and that the tertiary amines (N3) have the highest affinity toward CO 2 . Our study provides a novel strategy for designing high-performance adsorbents for CO 2 adsorption and separation.