Ab initio study of metal-decorated carbon and silicon prismanes as the selective CO2 adsorbents

Abstract

Abstract: In this paper, we conducted comprehensive analysis of the selective adsorption of CO2 by carbon and silicon prismanes along with metal ions. The results of calculations from B3LYP/6-31G(d,p) and M06-2X/6-31G(d,p) levels of theory show that Be2+ , Mg2+ , Ca2+ and Li+ , Na+ , K+ ions are bounded strongly enough to prismanes. The Be2+ ion binds more strongly to the C8 H8 cubane with binding energy 9.66eV compared to Li+ , Na+ , K+ , Mg2+ and Ca2+ ions having binding energies 1.26, 0.63, 0.51, 4.60 and 3.36eV, respectively. Similar results were obtained for larger prismanes C10 H10 and C12 H12 . Instead of binding energy, we determine the adsorption of gases on metal-ion prismane complex along with effect of temperature on different gas adsorption shows that C8H8_Mg2+ and C8H8_Be2+ are active adsorbents at temperatures above room temperature. It is also observed that in comparison to N2 and CH4, CO2 interacts more strongly with all prismanes decorated with metal ions. These non-covalent interaction plots are used to study the prismane and metal-ion interaction. Comparable study of silicon prismanes with M06 2X/6-31G (d, p) basis set, in terms of binding energy, adsorption of gases on prismane along with temperature effect, also possesses similar selectivity to CO2 molecule with even higher adsorption energies. Thus, beryllium-decorated prismanes can be considered as promising adsorbents of carbon dioxide with good selectivity and high adsorption energy.