Theoretical Predicted Surface Morphology of FCC Cobalt Nanoparticles Induced by Ru Promoter
The experimental shape control of metallic Co nanoparticles (NPs) remains a great challenge for the direct characterization for further rational design and optimization of efficient nanocatalysts nowadays, especially with low content of promoters involved. Thus, spin-polarized density functional theory (DFT) along with ab initio molecular dynamics (AIMD) simulations have been carried out to investigate the adsorption configurations and growth modes of Run clusters on Co surfaces for systemically exploring the surface morphology of Co NPs induced by Ru promotion in Co-based Fischer-Tropsch synthesis (FTS). The predicted Run aggregation growth modes on Co(100) and Co(110) surfaces combined with those recently results of Co(111) and Co(311) surfaces showed the thermodynamic growth tendency that Run are favorable for planar layered growth on Co surfaces under realistic FTS reaction condition, which is consistent with the experimental EELS spectral results. The addition of Ru promoter has an important role in tuning the stability of the exposed facets of face centered-cubic (FCC) Co NPs, accompanied by the change of morphology from truncated octahedron to rhombic dodecahedron. When at high Ru content, the increased high index Co(311) and Co(110) surfaces including more active step and kink sites are desired for the enhanced activity of FCC Co NPs.