PdNi Alloy Nanoparticles Research Articles

Graphene-supported NiPd alloy nanoparticles: A novel and highly efficient heterogeneous catalyst system for the reductive amination of aldehydes

A novel and highly efficient heterogeneous catalytic reductive amination of aldehydes is described. The recently developed graphene supported NiPd alloy nanoparticle (G-NiPd) catalyst using ammonia borane (AB) as a green, stable and safe hydrogen donor was used in a water/methanol mixture (v/v=2/3) under ambient conditions. The catalytic system was successfully applied in the reductive amination of various substituted aldehydes with amines and the corresponding products were obtained in (up to) 99% yield in 6h. The G-NiPd catalyst could be recycled up to five times without any significant loss in the product yield.

Highly sensitive electrochemical immunosensor for the detection of alpha fetoprotein based on PdNi nanoparticles and N-doped graphene nanoribbons.

An ultrasensitive sandwich-type electrochemical immunosensor was designed for the quantitative detection of alpha fetoprotein (AFP). The β-cyclodextrins functionalized graphene sheets (CD-GS) were used as the sensing matrix for immobilizing adamantine-1-carboxylic acid functionalized primary anti-AFP (ADA-Ab1) and enhanced the electron transfer. PdNi alloy nanoparticles decorated N-doped graphene nanoribbons (PdNi/N-GNRs) were used as labels of secondary anti-AFP (Ab2), and PdNi alloy nanoparticles (PdNi NPs) exhibited high catalytic performance towards the reduction of H2O2. Meanwhile, with good dispersion, large specific surface area and good catalytic performance, N-doped graphene nanoribbons (N-GNRs) significantly amplified the electrochemical signal. Under the optimal conditions, the electrochemical immunosensor exhibited a wide linear range of 0.0001-16 ng/mL with a low detection limit of 0.03 pg/mL. Additionally, the proposed immunosensor showed high specificity, good reproducibility and long-term stability, which have promising application in bioassay analysis.

Pd–Ni Alloy Nanoparticles as Effective Catalysts for Miyaura–Heck Coupling Reactions

In this work, Pd–Ni alloy nanoparticles (NPs) were produced by a facile and efficient one-pot synthetic strategy in the presence of oleylamine (OAm) and triphenylphosphine (TPP). Transmission electron microscopy (TEM), energy-dispersive spectrometry (EDS) mapping, inductively coupled plasma atomic emission spectroscopy (ICP-AES), and X-ray diffraction (XRD) were used to investigate the structure of Pd–Ni alloy NPs, which demonstrated that the as-prepared alloy NPs possessed uniform sizes and tunable compositions. Importantly, we found that TPP could affect the morphology of the Pd–Ni alloy. When TPP was absent from the reaction, the morphology of the Pd–Ni alloy was not uniform. In addition, the as-prepared Pd–Ni alloy NPs showed conspicuous composition-dependent catalytic activities for the Miyaura–Heck reaction. In the series of the Pd–Ni alloy NPs, Pd1Ni1 has an excellent effect for the Miyaura–Heck reactions. Furthermore, the Pd–Ni alloy NPs were also effective for different substrates in the Miyaura–...

Monodisperse nickel–palladium alloy nanoparticles supported on reduced graphene oxide as highly efficient catalysts for the hydrolytic dehydrogenation of ammonia borane

Addressed herein is the catalysis of reduced graphene oxide-supported monodisperse NiPd alloy nanoparticles (NPs) (rGO-NiPd) in the hydrolytic dehydrogenation of ammonia borane (AB). This is the first example of the use of NiPd alloy NPs as catalyst in the hydrolytic dehydrogenation of AB. Monodisperse NiPd alloy NPs (3.5 nm) were synthesized by co-reduction of nickel(II) acetate and palladium(II) acetylacetonate in oleylamine (OAm) and borane-tert-butylamine complex (BTB) at 100 °C. The current recipe allowed to control the composition of NiPd alloy NPs and to study the composition-controlled catalysis of rGO-NiPd in the hydrolytic dehydrogenation of AB. Among the all compositions tested, the Ni30Pd70 was the most active one with the turnover frequency of 28.7 min−1. The rGO-Ni30Pd70 were also durable catalysts in the hydrolytic dehydrogenation of AB providing 3650 total turnovers in 35 h and reused at six times without deactivation. The detailed reaction kinetics of hydrolytic dehydrogenation of AB revealed that the reaction proceeds first order with respect to the NiPd concentration and zeroth order with respect to the AB concentration. The apparent activation energy of the catalytic dehydrogenation of AB was also calculated to be Eaapp = 45 ± 2 kJ*mol−1.

Pd-Ni alloy nanoparticle/carbon nanofiber composites: preparation, structure, and superior electrocatalytic properties for sugar analysis.

Novel Pd-Ni alloy nanoparticle/carbon nanofiber (Pd-Ni/CNF) composites were successfully prepared by a simple method involving electrospinning of precursor polyacrylonitrile/Pd(acac)2/Ni(acac)2 nanofibers, followed by a thermal process to reduce metals and carbonize polyacrylonitrile. The nanostructures of the resulting Pd-Ni/CNF nanocomposites were carefully examined by a combination of scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), high-angle annular dark field (HAADF)-scanning transmission electron microscopy (STEM), energy dispersive X-ray (EDX), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and X-ray photoelectron spectra (XPS). For all the nanocomposites, the Pd-Ni alloy nanoparticles (NPs) were dispersed uniformly and embedded firmly within the framework or on the surface of CNF. The size, composition, and alloy homogeneity of the Pd-Ni alloy NPs could be readily tailored by controlling the feed ratio of metal precursors and the thermal treatment process. Cyclic voltammetric studies showed enhanced redox properties for Pd-Ni/CNF-based electrodes relative to the Ni-metal electrode and significantly improved electrocatalytic activity for sugar (e.g., glucose, fructose, sucrose, and maltose) oxidation. The application potential of Pd-Ni/CNF-based electrodes in flow systems for sugars detection was explored. A very low limit of detection for sugars (e.g., 7-20 nM), high resistance to surface fouling, excellent signal stability and reproducibility, and a very wide detection linear range (e.g., 0.03-800 μM) were revealed for this new type of Pd-Ni/CNF nanocomposite as the detecting electrode. Such detection performances of Pd-Ni/CNF-based electrodes are superior to those of state-of-the-art nonenzymatic sugar detectors that are commercially available or known in the literature.

Tandem Dehydrogenation of Ammonia Borane and Hydrogenation of Nitro/Nitrile Compounds Catalyzed by Graphene-Supported NiPd Alloy Nanoparticles

We report a facile synthesis of monodisperse NiPd alloy nanoparticles (NPs) and their assembly on graphene (G) to catalyze the tandem dehydrogenation of ammonia borane (AB) and hydrogenation of R-NO2 and/or R-CN to R-NH2 in aqueous methanol solutions at room temperature. The 3.4 nm NiPd alloy NPs were prepared by coreduction of nickel(II) acetate and palladium(II) acetlyacetonate by borane-tert-butylamine in oleylamine and deposition on G via a solution phase self-assembly process. G-NiPd showed composition-dependent catalysis on the tandem reaction with G-Ni30Pd70 being the most active. A variety of R-NO2 and/or R-CN derivatives were reduced selectively into R-NH2 via G-Ni30Pd70 catalyzed tandem reaction in 5–30 min reaction time with the conversion yields reaching up to 100%. Our study demonstrates a new approach to G-NiPd-catalyzed dehydrogenation of AB and hydrogenation of R-NO2 and R-CN. The G-NiPd NP catalyst is efficient and reusable, and the reaction can be performed in an environment-friendly process with short reaction times and high yields.

Hydrogen Storage in Porous Single-Walled Carbon Nanohorns Dispersed with Pd–Ni Alloy Nanoparticles

Single-walled carbon nanohorns containing Pd–Ni alloy nanoparticles (Pd–Ni/SWCNHs) were prepared by the gas-injected arc-in-water method, and high-pressure H2 absorption by these nanoparticles was investigated using a magnetic suspension balance at 30 °C and 1.2 MPa. The amount of H2 absorbed by them was larger than the predicted combined absorption contributed by Pd–Ni alloy and pure-carbon SWCNHs. This synergetic H2 absorption was induced by the combination of Pd–Ni alloy nanoparticles and SWCNHs and occurred because of a spillover effect. Remarkably, H2 absorption occurred by diffusing into as-grown Pd–Ni/SWCNHs. Opening the pores of Pd–Ni/SWCNHs by a mild oxidation treatment drastically improved the H2 absorption. Consequently, the diffusivity of H2 into Pd–Ni/SWCNHs was enhanced to the point where H2 absorption could reach saturation in an extremely short time.

Molecular Dynamics Simulation of Solidification of Pd-Ni Clusters with Different Nickel Content

Molecular dynamics simulation has been performed for investigating the glass transition of Pd-Ni alloy nanoparticles in the solidification process. The results showed that the Pd-Ni nanoparticles with composition far from pure metal should form amorphous structure more easily, which is in accordance with the results of the thermodynamic calculation. There are some regular and distorted fivefold symmetry in the amorphous Pd-Ni alloy nanoparticles. The nanoclusters with bigger difference value between formation enthalpies of solutions and glasses will transform to glass more easily than the other Pd-Ni alloy nanoclusters.

Gas Flow Rate in the Gas-Injected Arc-in-Water Method as a Critical Factor to Synthesize High-Dispersion Pd–Ni Alloy Nanoparticles in Single-Walled Carbon Nanohorns

Gas Flow Rate in the Gas-Injected Arc-in-Water Method as a Critical Factor to Synthesize High-Dispersion Pd–Ni Alloy Nanoparticles in Single-Walled Carbon Nanohorns

Nanoporous PdNi/C Electrocatalyst Prepared by Dealloying High‐Ni‐content PdNi Alloy for Formic Acid Oxidation

AbstractTo improve the electrochemical performance of Pd‐based catalysts for formic acid oxidation, a carbon supported nanoporous PdNi catalyst is prepared by dealloying high‐Ni‐content PdNi alloy nanoparticles in acid solution. The structure of nanoporous PdNi/C catalyst is characterized by X‐ray diffraction, transmission electron microscopy and X‐ray photoelectron spectroscopy. The electrocatalytic results show that the activity of the nanoporous PdNi/C catalyst is higher than that of nonporous Pd/C catalyst. The results demonstrate that the carbon‐supported nanoporous PdNi catalyst has a potential for application in direct formic acid fuel cells.

One-step synthesis of single-walled carbon nanohorns dispersed with Pd-Ni alloy nanoparticles by gas-injected arc-in-water method and effects of synthesis factors on their hydrogen sensor sensitivity

Single-walled carbon nanohorns (SWCNHs) dispersed with Pd-Ni alloy nanoparticles were synthesized in a technique requiring a single step by a gas-injected arc-in-water method using Pd-Ni-C mixed powders charged in an anode hole. It was found that the Ni/Pd weight ratio in the alloy nanoparticles dispersed in the products uniquely depended on the initial Ni/Pd weight ratio; Pd in the products was enriched by a factor of two when the Ni/Pd weight ratio in the initial mixture was higher than 0.1, while Ni was enriched at a Ni/Pd weight ratio below this threshold. The average diameter of alloy nanoparticles increased with the initial weight of the metallic components, while the average diameter of the discrete forms of the SWCNH aggregates exhibited the opposite tendency. Increasing the amount of the metallic compounds in the initial mixed powders caused the enrichment of Pd. The effect of adding Pd-Ni alloy nanoparticles into the products on the carbonaceous structures of SWCNHs was not detected by Raman analysis. The sensitivities of H2 sensors using the SWCNHs dispersed with Ni, Pd, and Pd-Ni alloy nanoparticles were compared, and the sensitivity of the sensor using the Pd-Ni alloy was the highest.

One-Pot Synthesis of Monodisperse 5 nm Pd–Ni Nanoalloys for Electrocatalytic Ethanol Oxidation

Highly monodisperse 5 nm Pd-Ni alloy nanoparticles (NPs) were prepared by the reduction of Pd(acac)(2)/Ni(acac)(2) mixtures with tert-butylamine-borane complex (TBAB) in the presence of oleic acid (OA) and oleylamine (OAm). Employing TBAB as an effective reductant and OA/OAm combination as an effective stabilizing agent is crucial to the formation of monodisperse Pd-Ni NPs. Experimental results collectively verify that the Pd-Ni alloy NPs form through the sequential nucleation-interdiffusion process and the simultaneous reduction of both metal precursors by the one-pot protocol is the key to the formation of homogeneous NPs. The Pd-Ni NPs were well-dispersed on carbon supports and chemically dealloyed after acetic acid washing through the selective dissolution of the less noble Ni component. The Pd-Ni NP catalysts exhibited much higher electrocatalytic activity and stability for ethanol oxidation than those of a commercial Pd/C catalyst.

Modelling of the Formation of Pd-Ni Alloy Nanoparticles by Interdiffusion

Long–time scale molecular dynamics simulation in combination with the embedded atom method is used to investigate the effect of surface segregation phenomena at 1000 K on the structure of Pd alloy nanoparticles (of diameter of ∼ 4.5 nm) containing ∼ 30 at. % Ni. A core–shell f.c.c. structure was chosen as the initial state wherein a core of Ni atoms is surrounded by shell of Pd atoms. It is found that such nanoparticles form a surface–sandwich structure by interdiffusion. In this structure, the Ni atoms, which mostly accumulate in a layer just below the surface and at the same time are located in the centres of interpenetrating icosahedra to generate a subsurface shell as a Kagomé net. Meanwhile, the Pd atoms occupy the vertices of the icosahedra and cover this Ni layer from inside and outside as well as being located in the core of the nanoparticle forming (according to alloy composition) a Pd–rich solid solution with the remaining Ni atoms. The total atomic fraction involved in building up the shell of the nanoparticle in the form of the Ni Kagomé net layer covered on both side by Pd atoms can be estimated at ∼ 70 %.