Electronic structure and stability of the pentlanditesCo9S8and(

Abstract

First-principle electronic structure investigations of transition-metal sulfides Co 9 S 8 and related alloys with the unique structure of pentlandite are carried out using density-functional theory within the local-density approximation. The total-energy calculations for Co 9 S 8 and (Fe,Ni) 9 S 8 alloys have been computed and we predict equilibrium lattice parameters that are on average 1% smaller than in the experiment. The heats of formation have been calculated, the theoretical prediction for Co 9 S 8 being in excellent agreement with that available in the Thermocalc database. The predicted heat of formation for the Fe 5 Ni 4 S 8 alloy is very close to Co 9 S 8 , reflecting the fact that the Fermi level is found to fall in a pseudogap for an average number of valence electrons per atom e/aϭ7.58. Furthermore, we determined the individual bond energies for Co 9 S 8 and Co 8 S 8 to stress the contribution of the octahedral metal cobalt to the stability of the Co 9 S 8 phase.

D-tracer study of butadiene hydrogenation and tetrahydrothiophen hydrodesulphurisation catalysed by Co9S8

“…This distance is similar to the nearest neighbour distance in cobalt metal which is 0.251 nm. Considerable orbital overlap between these ions contributes to the electronic [10], magnetic [11,12], and metallic [13] properties of Co 9 S 8 . Of the 32 octahedral holes, 28 are pseudooctahedral, distorted, and empty, whereas four are truly octahedral and each contains a Co atom in a formally zero oxidation state.…”

Hierarchical CoNi‐Sulfide Nanosheet Arrays Derived from Layered Double Hydroxides toward Efficient Hydrazine Electrooxidation

“…DFT calculations were carried out to give an insight into the activity of CoNi‐alloy@CoNi‐sulfide toward hydrazine electrooxidation. The as‐obtained CoNi‐sulfide (Ni 3 Co 6 S 8 ) possesses a face‐centered cubic structure ( Figure a) . The CoNi‐oxide (NiCo 2 O 4 ) with face‐centered cubic structure was used as a control sample (Figure S21, Supporting Information).…”

One-step solid phase synthesis of a highly efficient and robust cobalt pentlandite electrocatalyst for the oxygen evolution reaction

“…30,33,34 In addition, theoretical studies also suggest the superior stability of Co 9 S 8 over other cobalt sulfides owing to its unique crystal structure. 35 In the primitive unit cell of Co 9 S 8 , there is one Co atom at the octahedral site (Co(O)), and the remaining eight Co atoms are at the tetrahedral sites (Co(T)). The formation of Co(O) and S further stabilises the Co 9 S 8 crystals.…”