Highly Active Bimetallic Nickel-Palladium Alloy Nanoparticle Catalyzed Suzuki-Miyaura Reactions

Kinetically Controlled Synthesis of Metallic Glass Nanoparticles with Expanded Composition Space

Nanoscale metallic glasses offer opportunities for investigating fundamental properties of amorphous solids and technological applications in biomedicine, microengineering, and catalysis. However, their top-down fabrication is limited by bulk counterpart availability, and bottom-up synthesis remains underexplored due to strict formation conditions. Here, a kinetically controlled flash carbothermic reaction is developed, featuring ultrafast heating (>105 K s-1) and cooling rates (>104 K s-1), for synthesizing metallic glass nanoparticles within milliseconds. Nine compositional permutations of noble metals, base metals, and metalloid (M1─M2─P, M1 = Pt/Pd, M2 = Cu/Ni/Fe/Co/Sn) are synthesized with widely tunable particle sizes and substrates. Through combinatorial development, a substantially expanded composition space for nanoscale metallic glass is discovered compared to bulk counterpart, revealing that the nanosize effect enhances glass forming ability. Leveraging this, several nanoscale metallic glasses are synthesized with composition that have never, to the knowledge, been synthesized in bulk. The metallic glass nanoparticles exhibit high activity in heterogeneous catalysis, outperforming crystalline metal alloy nanoparticles.

Sustainable Routes for the Synthesis of Renewable Adipic Acid from Biomass Derivatives

Adipic acid (AA) is a key industrial dicarboxylic acid intermediate used in nylon manufacturing. Unfortunately, the traditional process technology is accompanied by serious environmental pollution. Given the growing demand for adipic acid and the desire to reduce its negative impact on the environment, considerable efforts have been devoted to developing more green and friendly routes. This Review is focused on the latest advances in the sustainable preparation of AA from biomass-based platform molecules, including 5-hydroxymethylfufural, glucose, γ-valerolactone, and phenolic compounds, through biocatalysis, chemocatalysis, and the combination of both. Additionally, the development of state-of-the-art catalysts for different catalytic systems systematically is discussed and summarized, as well as their reaction mechanisms. Finally, the prospects for all preparation routes are critically evaluated and key technical challenges in the development of green and sustainable processes for the manufacture of AA are highlighted. It is hoped that the green adipic acid synthesis pathways presented can provide insights and guidance for further research into other industrial processes for the production of nylon precursors in the future.

Prospects and Applications of Palladium Nanoparticles in the Cross-coupling of (hetero)aryl Halides and Related Analogues

Discovering efficient methods for the formation of carbon-carbon bonds is a central ongoing theme in organic synthesis. Cross-coupling reactions catalysed by metal nanoparticles are attractive alternatives to the traditional use of metal counterparts due to the catalytic tunability, selectivity, recyclability and reusability of the nanoparticles. The ongoing search for sustainable processes demands that reusable and environmentally benign catalysts are used. While the advantages of nanoparticles catalysts over bulk catalysts cannot be overemphasised, the problem of sintering, agglomeration and leaching are drawbacks to their full industrial applications. Hence, efforts are being made towards advancing the efficiency of the catalytic nanoparticle systems over the years. This review presents the progress, the challenges and the prospects of palladium nanoparticle with focus on Heck, Suzuki, Hiyama and Sonogashira cross-coupling reactions involving (hetero) aryl halides and the analogues.

Catalytically active nanosized Pd9Te4 (telluropalladinite) and PdTe (kotulskite) alloys: first precursor-architecture controlled synthesis using palladium complexes of organotellurium compounds as single source precursors

Several intermetallic binary phases of Pd-Te including Pd3Te2, PdTe, PdTe2, Pd9Te4, Pd3Te, Pd2Te, Pd20Te7, Pd8Te3, Pd7Te2, Pd7Te3, Pd4Te and Pd17Te4 are known, and negligible work (except few studies on PdTe) has been done on exploring applications of such phases and their fabrication at nanoscale. Hence, Pd(ii) complexes Pd(L1)Cl2 and Pd(L2-H)Cl (L1): Ph-Te-CH2-CH2-NH2 and L2: HO-2-C6H4-CH[double bond, length as m-dash]N-CH2CH2-Te-Ph were synthesized. Under similar thermolytic conditions, complex Pd(L1)Cl2 with bidentate coordination mode of ligand provided nanostructures of Pd9Te4 (telluropalladinite) whereas Pd(L2-H)Cl with tridentate coordination mode of ligand yielded PdTe (kotulskite). Bimetallic alloy nanostructures possess high catalytic potential for Suzuki coupling of aryl chlorides, and reduction of 4-nitrophenol. They are also recyclable upto six reaction cycles in Suzuki coupling.

Heterogeneous catalysis by ultra-small bimetallic nanoparticles surpassing homogeneous catalysis for carbon-carbon bond forming reactions

Palladium catalyzed cross-coupling reactions represent a significant advancement in contemporary organic synthesis as these reactions are of strategic importance in the area of pharmaceutical drug discovery and development. Supported palladium-based catalysts are highly sought-after in carbon-carbon bond forming catalytic processes to ensure catalyst recovery and reuse while preventing product contamination. This paper reports the development of heterogeneous Pd-based bimetallic catalysts supported on fumed silica that have high activity and selectivity matching those of homogeneous catalysts, eliminating the catalyst's leaching and sintering and allowing efficient recycling of the catalysts. Palladium and base metal (Cu, Ni or Co) contents of less than 1.0 wt% loading are deposited on a mesoporous fumed silica support (surface area SABET = 350 m2 g-1) using strong electrostatic adsorption (SEA) yielding homogeneously alloyed nanoparticles with an average size of 1.3 nm. All bimetallic catalysts were found to be highly active toward Suzuki cross-coupling (SCC) reactions with superior activity and stability for the CuPd/SiO2 catalyst. A low CuPd/SiO2 loading (Pd: 0.3 mol%) completes the conversion of bromobenzene and phenylboronic acid to biphenyl in 30 minutes under ambient conditions in water/ethanol solvent. In contrast, monometallic Pd/SiO2 (Pd: 0.3 mol%) completes the same reaction in three hours under the same conditions. The combination of Pd with the base metals helps in retaining the Pd0 status by charge donation from the base metals to Pd, thus lowering the activation energy of the aryl halide oxidative addition step. Along with its exceptional activity, CuPd/SiO2 exhibits excellent recycling performance with a turnover frequency (TOF) of 280 000 h-1 under microwave reaction conditions at 60 °C. Our study demonstrates that SEA is an excellent synthetic strategy for depositing ultra-small Pd-based bimetallic nanoparticles on porous silica for SCC. This avenue not only provides highly active and sintering-resistant catalysts but also significantly lowers Pd contents in the catalysts without compromising catalytic activity, making the catalysts very practical for large-scale applications.

A magnetically retrievable air and moisture stable gold and palladium nanocatalyst for efficient C-C coupling reactions

In this study, we report the synthesis of a highly stable, magnetically retrievable gold and palladium nanocatalyst (AuPd@AMNPs), highly active in Suzuki cross-coupling and related homocoupling reactions. The active catalytic component in this system is palladium, which can only be stabilized in the presence of gold nanoparticles. There is no significant loss of activity even after prolonged storage exposed air and moisture. The versatile nature AuPd@AMNPs is demonstrated through the selective catalysis of the homocoupling of phenylboronic acid under low concentrations of O₂ and the oxidation of phenylboronic acid to phenol under high O₂ concentrations. AuPd@AMNPs also demonstrated Ullmann-type homocoupling of 4-iodotolene with excellent yields. The magnetically retrieved catalyst could be re-used up to six times in Suzuki-Miyaura cross-coupling with consistently high activity and with a minimal loss of the noble metal species. Through these reactions we show that the gold-stabilized AuPd@AMNPs can be used as stable and recyclable palladium reservoir for multiple palladium-catalysed reactions.

Terpyridine-based Pd(ii)/Ni(ii) organometallic framework nano-sheets supported on graphene oxide-investigating the fabrication, tuning of catalytic properties and synergetic effects

Tailoring the structures of catalysts and the arrangement of organic bimetallic catalysts are essential in both fundamental research and applications. However, they still impose enormous challenges such as size and active species distribution, ordered uniformity, and controllable composition, which are critical in determining their specific activities and efficiency. Herein, a novel terpyridine-based hetero-bimetallic Ni/Pd nanosheet supported on graphene oxide (denoted as GO@Tpy-Ni/Pd) was fabricated, which exhibited higher catalytic activity, substrate applicability and recyclability for the Suzuki coupling reaction under mild conditions. The catalytic mechanism was heterogeneous catalysis at the interface and the synergetic effect between Pd and Ni resulted in a little Ni(0)/Pd(0) cluster including Pd(ii)/Ni(ii) as a whole being formed through electron transfer on the catalytic surface. This phenomenon could be interpreted as the nanoscale clusters of Ni/Pd being the real active centre stabilized by the ligand and GO and the synergetic effect. The absorption and desorption of different substrates and products on Ni/Pd clusters, as calculated by DFT, was proved to be another key factor.

The synergistic effect between Ni and Pd atom was the crucial factor for enhancing catalytic activity.

Synergistic effect of the Pd–Ni bimetal/carbon nanofiber composite catalyst in Suzuki coupling reaction

A novel Pd₁Ni₄ bimetal nanocomposite catalyst was prepared and showed better performance than their monometallic counterpart. What's more, the catalyst could be reused ten times without significant change in catalytic activity, which met the request of sustainable chemistry.

Pd–Ni Bimetallic Nanoparticles Supported on Zro2 as an Efficient Catalyst for Suzuki–Miyaura Reactions

Pd–Ni bimetallic nanoparticles (BMNPs) supported on ZrO2 were prepared by an impregnation–reduction method. The BMNPs showed excellent catalytic performance in Suzuki carbon–carbon cross-coupling reactions and almost quantitative conversion of the substrates was obtained under mild conditions in the absence of ligand. The excellent catalytic performance of the bimetallic catalyst could be a result of the synergistic effect between the two metal components. The catalyst showed outstanding recyclability during the reaction process; no obvious decrease in catalytic performance was observed after five cycles.

Ultrasonic assisted synthesis of palladium-nickel/iron oxide core-shell nanoalloys as effective catalyst for Suzuki-Miyaura and p-nitrophenol reduction reactions

In this study, ultrasonic assisted synthesis of Pd-Ni/Fe₃O₄ core-shell nanoalloys is reported. Unique reaction condition was prepared by ultrasonic irradiation, releasing the stored energy in the collapsed bubbles and heats the bubble contents that leads to Pd(II) and Ni(II) reduction. Co-precipitation method was applied for the synthesis of Fe₃O₄ nanoparticles (NPs). Immobilized solution was produced by sonicating the aqueous mixture of Fe₃O₄ and mercaptosuccinic acid to obtain Pd-Ni alloys on Fe₃O₄ magnetic NP cores. The catalytic activity of the synthesized Pd-Ni/Fe₃O₄ core-shells was investigated in the Suzuki-Miyaura CC coupling reaction and 4-nitrophenol reduction, which exhibited a high catalytic activity in both reactions. These magnetic NPs can be separated from the reaction mixture by external magnetic field. This strategy is simple, economical and promising for industrial applications.

Pd(0)-CMC@Ce(OH)(4) organic/inorganic hybrid as highly active catalyst for the Suzuki-Miyaura reaction

A very easy sequential metathesis for the synthesis of Pd(II)-CMC@Ce(OH)₄ organic/inorganic hybrid and its application as effective pre-catalyst for the Suzuki-Miyaura reaction have been reported. It was found that the Pd nanoparticles (Pd NPs) were formed in situ in the course of the Suzuki-Miyaura couplings when Pd(II)-CMC@Ce(OH)₄ was used as a pre-catalyst. The activity of the Pd NPs in the reaction was enhanced synergistically by the unique redox properties (Ce³⁺/Ce⁴⁺) of Ce(OH)₄ and coordination with carboxyl groups as well as free hydroxyl groups of the hybrid of CMC@Ce(OH)₄. The results exhibit the Pd(0)-CMC@Ce(OH)₄ is super over Pd(II)@CMC, Pd(II)@CeO₂, and Pd(II)@Ce(OH)₄ catalysts in the Suzuki-Miyaura reaction. Moreover, the catalyst could be easily separated by simple filtration and reused at least seven runs without losing its activity.

Catalytic aerial oxidation of 5-hydroxymethyl-2-furfural to furan-2,5-dicarboxylic acid over Ni–Pd nanoparticles supported on Mg(OH)2 nanoflakes for the synthesis of furan diesters

Ni–Pd/Mg(OH)₂-catalyzed efficient aerial oxidation of 5-HMF to FDCA for the synthesis of furan diesters as potential precursor for application in biomass-derived plastics.

Recyclable palladium–graphene nanocomposite catalysts containing ionic polymers: efficient Suzuki coupling reactions

Palladium nanoparticles on ionic polymer-doped graphene (Pd–IPG) nanocomposite catalysts exhibited efficient catalytic performance in Suzuki coupling reactions.

Catalytic reduction of 4-nitrophenol over Ni-Pd nanodimers supported on nitrogen-doped reduced graphene oxide

Catalytic reduction of toxic 4-nitrophenol to 4-aminophenol over magnetically recoverable nanocatalysts has attracted much attention. Herein, we report a Ni-Pd/NrGO catalyst through the growth of Ni-Pd nanodimers (NDs) on nitrogen-doped reduced graphene oxide (NrGO). The Ni-Pd NDs show a heterogeneous nanostructure with Ni and Pd subparts contacting with each other, remarkably different from the frequently-observed core/shell nanoparticles (NPs) or nanoalloy. The formation of Ni-Pd NDs follows an initial deposition of Pd NPs on the graphene and in-situ catalytic generation of Ni subparts over the newly-generated Pd NPs. The resulting Ni-Pd/NrGO exhibits a superior catalytic activity towards the reduction of 4-nitrophenol at room temperature with a high rate constant (3400s^-1g^-1) and a low activated energy (29.1kJmol^-1) as compared to unsupported Ni-Pd NDs and supported monometallic catalysts. The conversion rate of 4-NP is calculated to be 99.5% and the percent yield (%) of 4-AP is as high as 99.1%. A synergistic catalysis mechanism is rationally proposed, which is ascribed to the electronic modification of Ni-Pd metals due to the strong metal/support interaction (SMSI) effect as well as the electron transfer between Ni and Pd. The hybrid catalyst shows soft ferromagnetic properties and can be magnetically separated and recycled without obvious loss of activity.

Activated nanostructured bimetallic catalysts for C–C coupling reactions: recent progress

This minireview highlights the recent progress made in the last decade towards the development of activated bimetallic alloy nanoparticle catalysts for C–C coupling reactions, including asymmetric C–C bond coupling reactions.

Access to highly active Ni–Pd bimetallic nanoparticle catalysts for C–C coupling reactions

A facile access to highly active (with enhanced TONs/TOFs) and durable bimetallic Ni–Pd nanoparticle catalysts for C–C coupling reactions was achieved by tuning Ni to Pd atomic ratio in the Ni–Pd nanoparticle catalyst and therefore the electronic charge transfer from Ni to Pd.