A DFT study of the electronic structure of cobalt and nickel mono-substituted MoS2 triangular nanosized clusters

Molybdenum disulfide nanoparticles are of interest for their extensive use in heterogeneous catalysis. Here, we report a systematic density functional theory study carried out to investigate the electronic effects of Co(Ni) mono-substitutions on triangular molybdenum sulfide models of nanometric scale. On the basis of the electronic structure, the charge distribution and the Δ(ELUMO − EHOMO) gap analysis, the triangle molecular model with nickel substitution is identified as more favorable for inducing the best catalytic performance. Nickel consistently induces stronger electronic rearrangements than cobalt, on the molybdenum first-neighbor atoms, which are connected with its higher promoting effect. Charge distribution analysis points out a chemical reduction on the molybdenum sites when the cluster is doped. Moreover, nickel substitution produces smaller Δ(ELUMO − EHOMO) gaps than cobalt substitutions, revealing that Ni-doped clusters are more reactive.

Ni promotional effect is observed as an increase of projected density of states above the Fermi level, favoring the donation step in the C–S breaking bond of molecules under HDS process. The projected density of states below the Fermi level is diminished, reducing the states available for charge back-donation.Figure optionsDownload as PowerPoint slide