Interaction of alkali metals with the Fe3O4(1 1 1) Surface

The adsorption and interaction of alkali metals (Li, Na, K, Rb and Cs) with the Fetet1-terminated Fe3O4(1 1 1) surface have been computed at the level of density functional theory. At low coverage, adsorption of alkali metals on site-1 (Oa–Oc–Od) is energetically more favorable than on site-2 (Oa–Oc–Od). Li has the strongest adsorption energy, followed by K, Rb, Cs and Na. The computed net charges show that the alkali metals can donate electrons to surface Fe and O atoms in the order of Li < Na < K ≈ Rb ≈ Cs. It is also noted that increasing the coverage does not significantly improve the promoting effect of alkali metals. In addition, alkali metals can move facilely on the Fe3O4(1 1 1) surface.