Metal-inorganic-organic core–shell material as efficient matrices for CO₂ adsorption: Synthesis, properties and kinetic studies

A novel hydrochar-based core–shell material with improved affinity towards CO₂ was synthesized through encapsulation within ZnO shell, followed by chemical grafting to an organic moiety bearing terminal diethanolamino groups and further dispersion of Cu⁰ nanoparticles. Characterization through nitrogen adsorption–desorption isotherms with BET and BJH models, SEM, TEM, zeta potential measurements, FTIR spectroscopy, DSC and XPS analyses revealed a strong influence of the modification procedure on the performance of each material in CO₂ adsorption. The resulting metal-inorganic-organic-core–shell (MIOCS) displayed compacted structure with a wide pore size distribution that imposes intraparticle diffusion as a kinetic-controlling step. Cu-MIOCS showed an appreciable CO₂ retention capacity of 5.42 mmol/g compared to many adsorbents reported so far. This affinity towards CO₂ was explained in terms of physical and non-stoichiometric CO₂ condensation. This finding is of great importance, because it demonstrates that judicious modifications of vegetal-deriving wastes such as woods and other biomasses give rise to added-value materials as low cost and efficient gas adsorbents with high affinity towards CO₂.