Catalytic Activity Of Bimetallic Nanoparticles Research Articles

Catalytic activity of bimetallic nanoparticles based on iron and nickel sulfides for hydrogenolysis of heavy oil in case of Boca de Jaruco reservoir

This paper examines the transformation of heavy oil composition in porous media of carbonate reservoir rocks under hydrothermal processes in the presence of transition metal sulfides, which form in-situ from the organic-soluble precursors. It was revealed that catalysts significantly promoted the destruction of asphaltenes. Its content was reduced from 15 wt.% to 12 wt.% in the presence of iron-based catalyst. The bimetallic catalyst based on nickel and iron with the mass ratio of 1:1 exhibited the best performance in terms of reducing heavy oil viscosity. Combination of two different metals allowed to involve the wide ranges of carbon-heteroatom bonds, which are mainly concentrated in resins and asphaltenes, into the hydrogenolysis reactions. Irreversible reduction of heavy oil viscosity in-place not only eases the further downstream processes such as pipeline transportation and refinery, but also decreases carbon footprints of the produced oil owing to the increase in the intensity of hydrogenation processes.

Catalytic activity of bimetallic nanoparticles M@Pd (M = Ni, Cu, Ag, Pt, Au) in deoxygenation of carboxylic acids: a quantum chemical evaluation

Catalytic activity of bimetallic nanoparticles M@Pd (M = Ni, Cu, Ag, Pt, Au) in deoxygenation of carboxylic acids: a quantum chemical evaluation

Biotechnological synthesis of Pd/Ag and Pd/Au nanoparticles for enhanced Suzuki-Miyaura cross-coupling activity.

SummaryBimetallic nanoparticle catalysts have attracted considerable attention due to their unique chemical and physical properties. The ability of metal‐reducing bacteria to produce highly catalytically active monometallic nanoparticles is well known; however, the properties and catalytic activity of bimetallic nanoparticles synthesized with these organisms is not well understood. Here, we report the one‐pot biosynthesis of Pd/Ag (bio‐Pd/Ag) and Pd/Au (bio‐Pd/Au) nanoparticles using the metal‐reducing bacterium, Shewanella oneidensis, under mild conditions. Energy dispersive X‐ray analyses performed using scanning transmission electron microscopy (STEM) revealed the presence of both metals (Pd/Ag or Pd/Au) in the biosynthesized nanoparticles. X‐ray absorption near‐edge spectroscopy (XANES) suggested a significant contribution from Pd(0) and Pd(II) in both bio‐Pd/Ag and bio‐Pd/Au, with Ag and Au existing predominately as their metallic forms. Extended X‐ray absorption fine‐structure spectroscopy (EXAFS) supported the presence of multiple Pd species in bio‐Pd/Ag and bio‐Pd/Au, as inferred from Pd–Pd, Pd–O and Pd–S shells. Both bio‐Pd/Ag and bio‐Pd/Au demonstrated greatly enhanced catalytic activity towards Suzuki–Miyaura cross‐coupling compared to a monometallic Pd catalyst, with bio‐Pd/Ag significantly outperforming the others. The catalysts were very versatile, tolerating a wide range of substituents. This work demonstrates a green synthesis method for novel bimetallic nanoparticles that display significantly enhanced catalytic activity compared to their monometallic counterparts.

PtNi bimetallic nanoparticles loaded MoS2 nanosheets: Preparation and electrochemical sensing application for the detection of dopamine and uric acid

Composite nanomaterials are particularly useful and offer many excellent opportunities for electrochemical sensing application. Depending on the high catalytic activity of bimetallic nanoparticles, the large specific surface area, abundant active edges and co-catalytic function of MoS2 nanosheets, we, for the first time, prepared a novel PtNi bimetallic nanoparticles loaded MoS2 nanosheets (PtNi@MoS2) hybrid material by a co-reduction method for the electrochemical sensing application. The nanocomposite is characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS), and then casted on a bare glassy carbon electrode (GCE) to fabricate an electrochemical sensor (PtNi@MoS2/GCE). The electrochemical investigation showed that the sensor performed good selectivity and wide linear ranges for the simultaneous detection of dopamine (0.5–150 μM) and uric acid (0.5–600 μM). And the detection limits were down to 0.1 μM (S/N = 3) for both analytes.

Fingerprint Feature of Atomic Intermixing in Supported AuPd Nanocatalysts Probed by X-ray Absorption Fine Structure

We report on a systematic study of AuPd bimetallic nanoparticles (NPs) prepared from two-step sputtering deposition in the suspension of graphene and ionic liquid using X-ray absorption fine structure (XAFS) spectroscopy. As-synthesized AuPd bimetallic catalysts possess well-enhanced activity and stability compared with monometallic (Au-only or Pd-only) catalysts, suggesting the synergistic effect upon alloying. A structural model with the introduction of Pd to Au cluster is provided to study the formation of bimetallic NPs and to offer detailed insights into the local structure information (interaction between Au and Pd). A novel and significant fingerprint is proposed to depict the intermixing structure of AuPd bimetallic NPs. The present XAFS study reveals a fingerprint feature in k-space, which can be an evaluation of the extent of the Au–Pd intermixing on the atomic scale, corresponding to the catalytic activity of bimetallic nanoparticles. The systematic XAFS-based methodology, demonstrated here on ...

Enhanced Reduction of p-Nitrophenol by a Methanogenic Consortium Promoted by Metallic Nanoparticles

The present study reports the synthesis and characterization of metallic nanoparticles (NPs) of Pd and bimetallic alloys of PdCu NPs for their application as catalysts to achieve the microbial reduction of p-nitrophenol (PNP). Addition of bimetallic alloys of PdCu NPs to methanogenic sludge incubations increased up to threefold the rate of reduction of PNP. Moreover, their presence promoted a more efficient and selective reduction of PNP to the desired product (p-aminophenol) with negligible accumulation of toxic intermediates (p-nitroso-phenol and p-hydroxylamine-phenol), which prevailed in sludge incubations lacking nanocatalysts. PdCu NPs synthesized by adding precursors H2PdCl4 and H2CuCl4 independently and simultaneously to the synthesis vessel showed superior catalytic properties as compared to those produced by mixing the same precursors prior addition to the synthesis vessel. The enhanced catalytic properties of bimetallic NPs could be explained by higher physical stability and interfacial arrangement within PdCu alloys promoting a more efficient transfer of reducing equivalents derived from lactate/ethanol fermentation towards the target nitro group in PNP. A wastewater treatment technology, combining the microbial activity of methanogenic consortia and the catalytic activity of bimetallic NPs, is proposed as an alternative for the removal of recalcitrant pollutants from wastewaters.

Role of Ru Oxidation Degree for Catalytic Activity in Bimetallic Pt/Ru Nanoparticles

Understanding the intrinsic relationship between the catalytic activity of bimetallic nanoparticles and their composition and structure is very critical to further modulate their properties and specific applications in catalysts, clean energy, and other related fields. Here we prepared new bimetallic Pt–Ru nanoparticles with different Pt/Ru molar ratios via a solvothermal method. In combination with X-ray diffraction (XRD), transmission electron microscopy (TEM) coupled with energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and synchrotron X-ray absorption spectroscopy (XAS) techniques, we systematically investigated the dependence of the methanol electro-oxidation activity from the obtained Pt/Ru nanoparticles with different compositions under annealing treatment. Our observations revealed that the Pt–Ru bimetallic nanoparticles have a Pt-rich core and a Ru-rich shell structure. After annealment at 500 °C, the alloying extent of the Pt–Ru nanoparticles increased, and mor...

Levelling the playing field: screening for synergistic effects in coalesced bimetallic nanoparticles.

Depending on the synthetic methods, bimetallic nanoparticles can have either core-shell, phase segregated, alloy, or partially coalesced structures, presenting different degrees of atomic mixing on their surface. Along with the variations of size and morphology, the structural differences make it difficult to compare the catalytic activity of bimetallic nanoparticles. In this article, we developed a facile screening method that can focus on the synergistic effects rather than structural differences. Prefabricated nanoparticles are mixed together to form linear aggregates and coalesced to form bimetallic junctions. Their hollow silica shells allow materials transport but prevent further aggregation. With a level playing field, this screening platform can identify the best bimetallic combination for a catalytic reaction, before optimizing the synthesis. This approach is more advantageous than the conventional approaches where structural difference may have dominant effects on the catalytic performance.

ChemInform Abstract: Synergy in the Catalytic Activity of Bimetallic Nanoparticles and New Synthetic Methods for the Prepartation of Fine Chemicals

AbstractReview: [57 refs.

Synergy in the Catalytic Activity of Bimetallic Nanoparticles and New Synthetic Methods for the Preparation of Fine Chemicals

AbstractMetal nanoparticles receive tremendous interest as alternative catalysts in a quest to fill the gap between homogeneous and heterogeneous catalysis with selective and sophisticated reactions that occur in highly recyclable and scalable processes. In this area of research that is growing rapidly, we would like to focus on bimetallic nanoparticles and on how these particular materials have been used recently as nanocatalysts in fine‐chemicals synthesis and transformations. The synergistic effects observed with these nanocatalysts, either as nanoalloys or core–shell objects, that accounts for their superior activity and efficiency are discussed.