Ultrafine Nanoparticle‐Supported Ru Nanoclusters with Ultrahigh Catalytic Activity

Abstract

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.

Room‐Temperature Morphology‐Controlled Synthesis of Nickel and Catalytic Properties of Corresponding Ru/Ni Catalysts

“…It was mainly because Ru atoms were supported on their surface via galvanic replacement reaction method and readily oxidized upon exposure to air. However, the oxidation state ruthenium specie would be reduced to ruthenium(0) during the process of hydrogenation reaction at above 60 °C …”

Tiny Ruthenium‐Cobalt‐Cobalt Hydroxide Nanoparticles Supported on Graphene for Efficiently Catalyzing Naphthalene Complete Hydrogenation

“…The amount of ruthenium oxidation state is clearly much higher than that of ruthenium reduced state owing to the surface oxidation of small Ru(0) particles in air. But most of RuO 2 would be reduced to Ru(0) during the hydrogenation reaction at above 60 °C . In addition, the RuO 2 /Ru(0) mole ratio on the surface of Ru/Co/Co(OH) 2 /G is obviously much larger than that on the surface of Ru/G (Figure d) due to Ru with higher dispersion in Ru/Co/Co(OH) 2 /G.…”

“…Co/Co(OH) 2 /G was synthesized via chemical reduction strategy with hydrazine hydrate as reducing agent The Ru/Co/Co(OH) 2 /G sample was obtained by galvanic displacement reaction method .…”

“…This is probably because of the nano‐synergetic effect of Ru, Co and Co(OH) 2 active sites originating from the unique and novel nanostructure of Ru islands‐on‐Co/Co(OH) 2 NPs. This proposed effect is that hydrogen is absorbed and activated at ruthenium sites, cobalt hydroxide sites activate naphthalene and cobalt sites plays as a significant role of “bridge” for carrying the activated hydrogen species to the activated naphthalene …”

Nickel Hydroxide–Cobalt Hydroxide Nanoparticle Supported Ruthenium–Nickel–Cobalt Islands as an Efficient Nanocatalyst for the Hydrogenation Reaction

“…The activated Hs peciesr eacts with activatedt oluene through the spillover effect of the Ni and Co sites at the interface between Ru and Ni(OH) 2 -Co(OH) 2 [49][50][51][52][53] to form methyl cyclohexane. To luene is easily adsorbed and activated at the Ni(OH) 2 -Co(OH) 2 sites through electrophilic adsorption interactions between the p electrons of toluene and the positively chargedh oles of the nickel hydroxide-cobalt hydroxide NPs.…”