Uniform 3D NiMoS nanoflowers with self-assembled nanosheets were successfully synthesized via a simple hydrothermal growth method using cheap and nontoxic elemental sulfur as sulfur sources. The structure and morphology of the nanomaterials were characterized by SEM, TEM, XRD, Raman and XPS analyses, revealing that the NiMoS nanoflowers were composed of ultrathin nanosheets with a thickness of approximately 6-12 nm. The HRTEM results indicate that the curve/short MoS2 slabs on the nanosheets possess the characteristics of dislocations, distortions and discontinuity, which suggests a defect-rich structure, resulting in the exposure of additional Ni-Mo-S edge sites. The obtained NiMoS nanoflowers exhibited an excellent activity for thiophene hydrodesulfurization (HDS) and 4,6-dimethyldibenzothiophene deep HDS due to their high density of active sites. The outstanding HDS performance suggests that these NiMoS composites with a unique flower-like nanostructure could be useful as promising catalysts for deep desulfurization of fuel oils.

The ability to tune the surface partial charge of noble metal catalysts at the nanoscale size dimension is essential for harnessing the activity of nanocatalysts in many important environmental catalytic reactions, such as hydrocarbon oxidations. We report herein a synthetic pathway to control the catalyst−support interactions and enable a surface partial-charge-tuned enhancement of the nanocatalytic activity using titania-supported Pt nanoparticles for oxidation of toluene as a model system. This pathway involved the onepot wet-chemical synthesis of TiO 2 -supported ultrasmall Pt nanoparticles (1−5 nm) with a controlled morphology and size. The catalysts showed greatly enhanced activities for toluene oxidation, exhibiting a strong dependence on the support morphology (e.g., nanopowders, nanowires, nanotubes, and mesoporous structures). The tunable partial negative charges on Pt were achieved by suppressing roughening of the support surface, favoring O 2 spillover from TiO 2 to Pt. In situ DRIFT data further reveal two parallel pathways responsible for oxidation of the methyl group and opening of the aromatic ring, the latter of which is favored by the partial negatively charged Pt, leading to a high activity. These findings provided insights into tuning nanoscale catalytic properties, which has significant implications for the design of supported noble metal nanocatalysts for environmental catalysis.

Ru nanoclusters on Ni/Ni(OH)2 nanoparticles supported on carbon (Ru/Ni/Ni(OH)2/C) were successfully prepared and characterized. Ru/Ni/Ni(OH)2/C exhibited an unprecedented catalytic activity for naphthalene hydrogenation at room temperature due to synergetic catalysis.

The design of an ideal heterogeneous catalyst for hydrogenation reaction is to impart the catalyst with synergetic surface sites active cooperatively toward different reaction species. Herein a new strategy is presented for the creation of such a catalyst with dual active sites by decorating metal and metal oxide nanoparticles with ultrafine nanoclusters at atomic level. This strategy is exemplified by the design and synthesis of Ru nanoclusters supported on Ni/NiO nanoparticles. This Ru-nanocluster/Ni/NiO-nanoparticle catalyst is shown to exhibit ultrahigh catalytic activity for benzene hydrogenation reaction, which is 55 times higher than Ru-Ni alloy or Ru on Ni catalysts. The nanoclusters-on-nanoparticles are characterized by high-resolution transmission electron microscope, Cs-corrected high angle annular dark field-scanning transmission electron microscopy, elemental mapping, high-sensitivity low-energy ion scattering, and X-ray absorption spectra. The atomic-scale nanocluster-nanoparticle structural characteristics constitute the basis for creating the catalytic synergy of the surface sites, where Ru provides hydrogen adsorption and dissociation site, Ni acts as a "bridge" for transferring H species to benzene adsorbed and activated at NiO site, which has significant implications to multifunctional nanocatalysts design for wide ranges of catalytic reactions.