Density functional theory study on the interaction of CO2 with Fe3O4(111) surface

CO2 adsorption on the Fetet1- and Feoct2-tet1-terminated Fe3O4(111) surface was investigated in order to understand the adsorption mechanism of CO2 by using density functional theory (DFT). Both weak and strong adsorptions exist between the CO2 and the Fe3O4(111) surface. The preferred adsorption site was found to be the Od site on the Feoct2-tet1-termination, after adsorption, the CO2 molecule was bent and the CO bond was elongated, indicating the activation of CO2. And it is found that Feoct2-tet1-terminated Fe3O4(111) surface is more active than Fetet1-terminated surface, CO2 serves as a charge acceptor to withdraw electrons from the Feoct2-tet1-terminated Fe3O4(111) surface. In addition, partial density of states, electron localization function and difference electron density reveal that covalent bond was formed between the C atom of CO2 and the surface O atom. These results provide fundamental insight into the CO2 adsorption mechanism on Fe3O4(111) surface and potential application on the activation of CO2.