Regulating the effect of element doping on the CO2 capture performance of kaolinite: A density functional theory study

The CO2 adsorption on clay minerals such as kaolinite, mica and a al. attracts lots of research attentions for the potential applications in slowing down the greenhouse effect. The physical and chemical properties of kaolinites can be adjusted by the internal atomistic structures, especially the substitution of Al in the Al-O tetrahedrons. In this work, we utilize the density functional theory (DFT) calculations to explore the variation of the electronic structures of kaolinite before and after the elemental substitution of Al by Mn, Fe, Co, Ni, and Si, respectively. Then the interactions between CO2 and pristine or doped kaolinites (0 0 1) were systematically investigated by the analysis of the adsorption energy (E-ads), electron transferring and the density of states. Finally, Pearson correlation analysis reveal that the effects of the surface hydroxyl groups of kaolinite and the atomic radius of the doping atoms are the key factors in the kaolinites-CO2 interactions.