Understanding CO2 Adsorption on a M1 (M2)-Promoted (Doped) MgO–CaO(100) Surface (M1 = Li, Na, K, and Rb, M2 = Sr): A DFT Theoretical Study

Global warming has become the most serious environmental problem over the past few decades. To identify ways of removing CO2, which is one of the key factors for global warming, this study examined CO2 adsorption on a MgO–CaO(100) surface by density functional theory. Promoters (M1 = Li, Na, K, and Rb) and dopants (M2 = Sr) were introduced to the solid-solution system to explain each chemical effect on the strength of CO2 adsorption on the solid-solution surface. Among the other promoted systems, Li-promoted MgO–CaO(100) showed the highest CO2 adsorption energy of −2.37 eV. Sr doping was found to be useful for making this solid-solution system reversible CO2 adsorbent by tuning the adsorption energy on the surface to −1.93 eV. The charge distribution was analyzed to obtain a deeper understanding of the promoter/dopant effect on CO2 adsorption.