First-principles study of the nature of small nickel sulfide particles

The nature of small nickel sulfide clusters was explored using the atoms in molecules theory and a based-electrostatic potential methodology. It was found that Ni3S4, whose structure corresponds to a C-3V {7, 9, 3} pyramid, should be (at 0 K) the most stable of the studied nickel sulfide clusters. Electrostatic potential results suggest that the Lewis acidity of the studied cluster is much larger (and therefore much more HDS reactive) than the respective acidity of the practically inactive Ni3S2 (111) surfaces. Atomistic thermodynamic calculations have shown that at typical HDS working conditions very small particles of non supported nickel sulphide should be mainly present as Ni3S4 cluster.