The selectivity of the transition metals encapsulated in a Fe9O12 cage

Abstract

The transition metals (TM) doping a Fe9O12 cage have been systemically studied by density functional theory. And then the structures, electronic and magnetic properties of them have been discussed. It can be found that V, Nb, Mo, Ta and W atoms prefer to encapsulate in a Fe9O12 cage and then form a core@shell structure. Here, Ta@Fe9O12 is proposed to be the most favorable structure. Zr, Hf and Ta atoms are conducive to stabilize a Fe9O12 cage. All the TM doping Fe9O12 clusters are more kinetically active. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of TM doping Fe9O12 clusters are mostly by virtue of d orbital distribution. More electrons are transferred from the Zr and Hf atoms to the Fe9O12 cage than from other transition metals. Only the spin values of Mn, Cr, and Ti atoms in a Fe9O12 cage are higher than 2.5 μB.