Theoretical Investigation of Carbon Dioxide Adsorption on Li⁺-Decorated Nanoflakes

Recently, the capture of carbon dioxide, the primary greenhouse gas, has attracted particular interest from researchers worldwide. In the present work, several theoretical methods have been used to study adsorption of CO₂ molecules on Li⁺-decorated coronene (Li⁺@coronene). It has been established that Li⁺ can be strongly anchored on coronene, and then a physical adsorption of CO₂ will occur in the vicinity of this cation. Moreover, such a decoration has substantially improved interaction energy (E_int) between CO₂ molecules and the adsorbent. One to twelve CO₂ molecules per one Li⁺ have been considered, and their E_int values are in the range from -5.55 to -16.87 kcal/mol. Symmetry-adapted perturbation theory (SAPT0) calculations have shown that, depending on the quantity of adsorbed CO₂ molecules, different energy components act as the main reason for attraction. AIMD simulations allow estimating gravimetric densities (GD, wt.%) at various temperatures, and the maximal GDs have been calculated to be 9.3, 6.0, and 4.9% at T = 77, 300, and 400 K, respectively. Besides this, AIMD calculations validate stability of Li⁺@coronene complexes during simulation time at the maximum CO₂ loading. Bader's atoms-in-molecules (QTAIM) and independent gradient model (IGM) techniques have been implemented to unveil the features of interactions between CO₂ and Li⁺@coronene. These methods have proved that there exists a non-covalent bonding between the cation center and CO₂. We suppose that findings, derived in this theoretical work, may also benefit the design of novel nanosystems for gas storage and delivery.