Abstract
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.