Ab initio Studies of O-2 Adsorption on (110) Nickel-Rich Pentlandite (Fe4Ni5S8) Mineral Surface

作者：Mkhonto Peace P; Chauke Hasani R^*; Ngoepe Phuti E

来源：Minerals, 2015, 5(4): 665-678.

DOI：10.3390/min5040516

• nickel-rich pentlandite (Fe4Ni5S8)
• (110) surface
• oxidation
• adsorption energies
• density of states
• Bader analysis
• electronic properties
• isosurface charge density

Ab initio density functional theory was used to investigate the adsorption of oxygen molecule on the nickel-rich pentlandite (110) surface, which is important for mineral extraction. The three most reactive adsorption sites: Fe-top, Ni-top, and fcc-hollow have been considered. Firstly, the non-adsorbed pentlandite surface reflects the Ni atoms relaxing inwards. Consequently, their electronic structure showed high Fe 3d-orbital contribution than the Ni 3d-orbitals at the E-F (indicating that the Fe atoms are more reactive than Ni). Secondly, the O-2-adsorbed surface predicted lowest adsorption energy for Fe-top (-1.902 eV), as a more spontaneous reaction is likely to occur than on fcc-hollow (-1.891 eV) and Ni-top (-0.040 eV) sites, suggesting Fe preferential oxidation. The density of states indicates that the O-2 show prevalence of electrons in the pi(star)(p) antibonding orbitals, and are reduced to zero states at the valence band on metal-bonded oxygen (O1). The sigma(star)(p) orbital is observed to reside just above the E-F for Fe-top and fcc-hollow site, while on Ni-top is half-occupied for both metal-bonded oxygen (O1) and terminal oxygen (O2). Finally, the isosurface charge density difference showed electron (charge) depletion on Ni/Fe metals and accumulation on the O-2 molecule. Bader analysis indicated that the oxidized Fe and Ni atoms adopt more positive charge, while O-2 on Fe-top atoms possesses more negative charge than on Ni-top, resulting with O1 possessing a smaller charge than O2 atom.

• 出版日期2015-12