The equilibrium shape of fcc Ru nanoparticles under hydrogen atmosphere.

The experimental shape control of metallic Co nanoparticles (NPs) remains a great challenge in terms of their direct characterization for the further rational design and optimization of efficient nanocatalysts nowadays, especially when a low promoter content is involved. Thus, spin-polarized density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations have been carried out to investigate the adsorption configurations and growth trend of Ru_n clusters on Co surfaces to systemically explore the surface morphology of Co NPs induced by Ru promotion in Co-based Fischer–Tropsch synthesis (FTS). The predicted Ru_n aggregation adsorption patterns on Co(100) and Co(110) surfaces combined with the recent results for Co(111) and Co(311) surfaces show the thermodynamic growth tendency that Ru_n aggregates are favorable for planar layered growth on Co surfaces under realistic FTS reaction conditions, 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 from truncated octahedron to rhombic dodecahedron morphology. At high Ru content, the increased high index Co(311) and Co(110) surfaces, including more active step and kink sites, are desirable for the enhanced activity of FCC Co NPs.

Hydrogen storage has been a bottleneck factor for the application of hydrogen energy. Hydrogen storage capacity for titanium-decorated boron-doped C₂₀ fullerenes has been investigated using the density functional theory. Different boron-doped C₂₀ fullerene absorbents are examined to avoid titanium atom clustering. According to our research, with three carbon atoms in the pentagonal ring replaced by boron atoms, the binding interaction between the Ti atom and C₂₀ fullerene is stronger than the cohesive energy of titanium. The calculated results revealed that one Ti atom can reversibly adsorb four H₂ molecules with an average adsorption energy of −1.52 eV and an average desorption temperature of 522.5 K. The stability of the best absorbent structure with a gravimetric density of 4.68 wt% has been confirmed by ab initio molecular dynamics simulations. These findings suggest that titanium-decorated boron-doped C₂₀ fullerenes could be considered as a potential candidate for hydrogen storage devices.