Use Of Palladium Nanoparticles Research Articles

Assessment of palladium nanoparticles as chemical modifier for lead determination in leached extracts from petroleum waste by high-resolution continuum source atomic absorption spectrometry

ABSTRACT Palladium nanoparticles were evaluated as a potential chemical modifier for lead determination by high-resolution continuum source graphite furnace atomic absorption spectrometry. Hydrophilic palladium nanocubes and palladium nanospheres were synthesised with sizes varying from 3 to 22 nm. Positive effects in terms of sensitivity and thermal stability upon the use of palladium nanoparticles were observed, especially using the 3 nm spherical-shaped. The mass of modifier influenced the thermal stability and relative signal intensity of the analyte, although the effectiveness of the modifier appeared to be suppressed to an important extent in the presence of matrix components of the leached extracts obtained from petroleum wastes. The optimised pyrolysis and atomisation temperatures were, respectively, 800 °C and 2300 °C, using 200 ng of 3 nm palladium nanoparticles. The limit of detection (4 µg L−1) and the precision (better than 18 %) were considered satisfactory for the proposed analysis. The method accuracy, evaluated by recovery tests and by comparison with the results obtained using inductively coupled plasma mass spectrometry, was proven adequate to enable the determination of Pb in leached extracts from petroleum waste. The method was successfully applied to determine lead in leached extracts obtained from oily sludge and drill cuttings and the obtained concentrations ranged from <13 to 354.4 µg L−1.

Robust Colloidal Synthesis of Palladium-Gold Alloy Nanoparticles for Hydrogen Sensing.

Metal nanoparticles are currently used in a variety of applications, ranging from life sciences to nanoelectronic devices to gas sensors. In particular, the use of palladium nanoparticles is gaining increasing attention due to their ability to catalyze the rapid dissociation of hydrogen, which leads to an excellent response in hydrogen-sensing applications. However, current palladium-nanoparticle-based sensors are hindered by the presence of hysteresis upon hydride formation and decomposition, as this hysteresis limits sensor accuracy. Here, we present a robust colloidal synthesis for palladium–gold alloy nanoparticles and demonstrate their hysteresis-free response when used for hydrogen detection. The obtained colloidal particles, synthesized in an aqueous, room-temperature environment, can be tailored to a variety of applications through changing the size, ratio of metals, and surface stabilization. In particular, the variation of the viscosity of the mixture during synthesis resulted in a highly tunable size distribution and contributed to a significant improvement in size dispersity compared to the state-of-the-art methods.

Simultaneous determination of direct yellow 50, tryptophan, carbendazim, and caffeine in environmental and biological fluid samples using graphite pencil electrode modified with palladium nanoparticles

The present study reports the development of graphite pencil electrode modified with palladium nanoparticles (PdNPs) and its application as an electrochemical sensor for the simultaneous detection of direct yellow 50, tryptophan, carbendazim and caffeine in river water and synthetic urine samples. The combination involving the conductive surface of the graphite pencil electrode (GPE) and the enlargement of the surface area caused by the use of palladium nanoparticles (PdNPs) led to the improvement of the analytical performance of the proposed device. The surface of the GPE-PdNPs was characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The charge transfer kinetics of the electrode was evaluated based on the electrochemical analysis of the potassium ferricyanide redox probe. Using square wave voltammetry (SWV), well-defined and fully resolved anodic peaks were detected for the analytes, with peak-to-peak potential separation not less than 200 mV. Under optimised conditions, the following linear range concentrations were obtained: 0.99–9.9 μmol L−1 for direct yellow 50; 1.2–12 μmol L−1 for tryptophan; 0.20–1.6 μmol L−1 for carbendazim; and 25–190 μmol L−1 for caffeine. The sensor showed good sensitivity, repeatability, and stability. The device was successfully applied for the determination of analytes in urine and river water samples, where recovery rates close to 100% were obtained. Due to its low cost and reusability by simple polishing, the sensor has strong potential to be used as an electrochemical sensor for the determination of different analytes.

Preparation and Application of Palladium Nanoparticle Impregnated Chloromethylated Polysulfone Matrix as an Efficient Catalytic Membrane for Oxidation of Alcohols

Abstract The use of palladium nanoparticles embedded in a chloromethylated Polysulfone (CMPSf) matrix was developed for highly efficient oxidation of primary and secondary alcohols to corresponding aldehyde and ketone in organic solvent free condition. Pd (Π)/bis (2, 4-dihydroxybenzaldehyde) chelate chemically incorporated onto CMPSf was used to prepare beneficial catalytic membranes. Chemical structure and thermal properties of resulting membranes were characterized via FTIR, 1HNMR, UV-vis, TGA and DSC techniques. Morphology and particle distribution throughout the catalytic membranes was elucidated using FE-SEM. An average particle size of Pd nanoparticles was estimated about 20 nm by XRD technique. ICP technique proved that no Pd particles were leached out of the membrane into the solutions; hence the as-prepared catalytic membranes could be used several times without significant loss in their activities. This is in good accordance with formation of chemical bond between Pd and polymer matrix.

Use of palladium nanoparticles dispersed on GNS - modified with 10 wt%CoMoO4 as efficient bifunctional electrocatalysts

Highly dispersed Pd-nanoparticles (NPs) are obtained on CoMoO4-doped graphene nano-sheets (GNS) by microwave-assisted polyol reduction method for use as electrocatalysts for methanol oxidation (MOR) and oxygen reduction (ORR) reactions. The activity of Pd/10 wt%CoMoO4-GNS towards MOR and ORR has been examined by cyclic (CV) and linear sweep (LSV) voltammetries and chronoamperometry measurements in 1 M KOH at 25 °C . The structural characterization of the hybrid catalyst was performed by X-ray diffraction, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. Results have shown that the novel Pd/10 wt%CoMoO4-GNS electrode has the MOR and ORR activities superior to Pd/GNS.

Palladium Nanoparticles in Polyols: Synthesis, Catalytic Couplings, and Hydrogenations.

Alcohols, in particular polyols, are well-known for the synthesis of metal nanoparticles, often acting as reducing agents, solvents, and stabilizers. Given not only their structural flexibility depending on the number of OH functions and their inherent H bonding interactions, but also the wide range of polyol molecular weights readily available, different physicochemical properties (boiling point, polarity, viscosity) could be exploited toward the synthesis of well-defined nanomaterials. In particular, the relevance of the supramolecular structure of polyols has a fundamental impact on the formation of metal nanoparticles, thereby favoring the dispersion of the nanoclusters. In the field of the metal-based nanocatalysis, palladium occupies a privileged position mainly due to its remarkable versatility in terms of reactivity representing a foremost tool in synthesis. In this review, we describe the controlled synthesis of Pd-based nanoparticles in polyol medium, focusing on the progress in terms of tailoring size, morphology, structure, and surface state. Moreover, we discuss the use of palladium nanoparticles, in a polyol solvent, applied in two of the most relevant Pd-catalyzed processes, i.e., couplings and hydrogenation reactions, including multistep processes.

The use of palladium nanoparticles supported on active carbon for synthesis of disproportionate rosin (DPR)

Disproportionate rosin (DPR) is a mixture of rosin acids with dehydro-abietic acid as its major component. Alkaline salts of DPR are used as emulsifier surfactant in emulsion polymerization reactions. In this work, synthesis of DPR by the use of palladium nanoparticles loaded on activated carbon was studied. The nanocatalyst was characterized by TEM, SEM, XRD, N2 adsorption–desorption and AAS. The reusability of the prepared nanocatalyst was successfully examined three times with only a very slight loss of catalytic activity.

Palladium nanoparticles exposure: Evaluation of permeation through damaged and intact human skin

The intensified use of palladium nanoparticles (PdNPs) in many chemical reactions, jewellery, electronic devices, in car catalytic converters and in biomedical applications lead to a significant increase in palladium exposure. Pd can cause allergic contact dermatitis when in contact with the skin. However, there is still a lack of toxicological data related to nano-structured palladium and information on human cutaneous absorption. In fact, PdNPs, can be absorbed through the skin in higher amounts than bulk Pd because NPs can release more ions. In our study, we evaluated the absorption of PdNPs, with a size of 10.7 ± 2.8 nm, using intact and damaged human skin in Franz cells. 0.60 mg cm−2 of PdNPs were applied on skin surface for 24 h. Pd concentrations in the receiving solutions at the end of experiments were 0.098 ± 0.067 μg cm−2 and 1.06 ± 0.44 μg cm−2 in intact skin and damaged skin, respectively. Pd flux permeation after 24 h was 0.005 ± 0.003 μg cm−2 h−1 and 0.057 ± 0.030 μg cm−2 h−1 and lag time 4.8 ± 1.7 and 4.2 ± 3.6 h, for intact and damaged skin respectively.This study indicates that Pd can penetrate human skin.

Green synthesis and catalytic properties of palladium nanoparticles for the direct reductive amination of aldehydes and hydrogenation of unsaturated ketones

This paper reports on the synthesis and use of palladium nanoparticles as heterogeneous catalysts for the reductive amination of aldehydes and hydrogenation of unsaturated ketones. This method has the advantages of high yields, simple methodology and easy work up. The catalyst can be recovered and reused several times without significant loss of catalytic activity.

The use of palladium nanoparticles supported on graphene oxide in the Mizoroki-Heck reaction

We have developed a convenient single-step method for producing palladium nanoparticles on the surface of graphene oxide by reducing palladium chloride with NaBH4. According to transmission electron microscopy data, palladium nanoparticles have a spheroidal shape; their sizes are 6–8 nm. The tests of immobilized palladium nanoparticles have shown that they exhibit high activity in the Mizoroki-Heck cross-coupling reaction.

Liquid–liquid microextraction based on a dispersion of Pd nanoparticles combined with ETAAS for sensitive Hg determination in water samples

A novel and highly efficient microextraction methodology based on the use of palladium nanoparticles (Pd NPs) was developed for the preconcentration and determination of Hg in water samples. Selective separation of the analyte was achieved by application of dodecanethiolate-coated Pd monolayer-protected clusters (C12S Pd MPCs) in a liquid–liquid microextraction technique (LLME). A volume of 20μL of toluene phase containing C12S Pd MPCs was used for extraction and final phase was injected in an electrothermal atomic absorption spectrometer (ETAAS) for Hg detection. The effects of different variables, such as sample volume, extraction time, and NPs dispersion volume were carefully studied. A sensitivity enchancement factor of 95 was obtained under optimal experimental conditions. Furthermore, low detection limit (7.5ngL−1) and good precision (relative standard deviation of 4.1% at 0.25μgL−1 Hg and n=10) were achieved. The proposed method can be considered as a rapid, cost-effective, and efficient alternative for Hg determination in water samples like river, lake, mineral and tap water.

Suzuki-Miyaura cross-coupling of arenediazonium salts catalyzed by alginate/gellan-stabilized palladium nanoparticles under aerobic conditions in water

The use of palladium nanoparticles stabilized by natural beads made of an alginate/gellan mixture in the Suzuki-Miyaura cross-coupling reaction of arenediazonium tetrafluoroborates with potassium aryltrifluoroborates (1 : 1 molar ratio) with loading as low as 0.01–0.002 mol% under aerobic, phosphine-, and base-free conditions in water is described. The catalyst system can be reused several times without significant loss of activity.

Palladium Nanoparticles on Amphiphilic Carbon Spheres: A Green Catalyst for Suzuki–Miyaura Reaction

AbstractWe report the use of palladium nanoparticles stabilized on amphiphilic glucose‐derived carbon spheres as heterogeneous catalysts for Suzuki–Miyaura reactions. Reactions of aryl halides with various boronic acids in the presence of different bases and solvents including organic polar, non‐polar and water as sole solvent without the aid of phase‐transfer catalysts, under phosphine‐free and aerobic conditions have been studied. Especially, deactivated aryl bromides and activated aryl chlorides afforded good isolated yields in pure water. The catalyst was reused for up to four cycles without any marked loss in the activity.

Magnetically Recoverable Palladium Nanocatalyst for Chemoselective Olefin Hydrogenation

Metal nanoparticles proved to be significantly more efficient than their bulk counterparts due to their large surface area. Recently, we reported the use of palladium nanoparticles entrapped in AlO(OH) matrix as the efficient racemization catalyst in the dynamic kinetic resolu-tion of primary amines.

Carbon-Carbon Cross Coupling Reactions in Ionic Liquids Catalysed by Palladium Metal Nanoparticles

A brief summary of selected pioneering and mechanistic contributions in the field of carbon-carbon cross-coupling reactions with palladium nanoparticles (Pd-NPs) in ionic liquids (ILs) is presented. Five exemplary model systems using the Pd-NPs/ILs approach are presented: Heck, Suzuki, Stille, Sonogashira and Ullmann reactions which all have in common the use of ionic liquids as reaction media and the use of palladium nanoparticles as reservoir for the catalytically active palladium species.

The use of palladium nanoparticles supported with MCM-41 and basic (Al)MCM-41 mesoporous sieves in microwave-assisted Heck reaction

A series of supported catalysts has been obtained by grafting of chemically generated palladium nanoparticles onto basic, Cs + ion-exchanged molecular sieves (Al)MCM-41 and onto the non-basic, parent material MCM-41. Catalytic activity of the catalysts has been investigated in the Heck reaction between bromobenzene and butyl acrylate under microwave irradiation. The activity of the bifunctional catalysts (Pd@Cs +-(Al)MCM-41) and the activity of Pd@MCM-41 combined with sodium acetate as an external base were considerably higher under microwave irradiation than activities observed for the same catalytic systems under the conventional heating. The Pd@MCM-41/NaOAc system showed higher conversions than the bifunctional catalysts presumably due to a different nature and accessible amount of the base. On the other hand, microwave irradiation seems to increase the rate of aggregation of the metallic particles and thus also catalyst deactivation as compared with the usual heating.

Suzuki‐ and Heck‐Type Cross‐Coupling with Palladium Nanoparticles Immobilized on Spherical Polyelectrolyte Brushes

AbstractWe report on a systematic study of the use of palladium nanoparticles immobilized on spherical polyelectrolyte brushes – Pd@SPB – for Heck‐ and Suzuki‐type coupling reactions. The spherical polyelectrolyte brush particles serving as carriers for the palladium nanoparticles consist of a solid polystyrene core with a radius of 46 nm onto which long chains of cationic polyelectrolytes are grafted. The palladium nanoparticles have directly been generated within this brush layer and the stabilization of the nanoparticles is effected by the colloidal carriers, no further surface stabilization is necessary. We demonstrate that these composite particles present robust catalysts for the Heck‐ and Suzuki‐type coupling reactions. This was shown by carrying out the Suzuki‐ and Heck‐type coupling reactions at relatively low temperatures (Suzuki reaction: 50 °C, Heck reaction: 70 °C). We demonstrate that the catalytic composite particles are not changed by these reaction conditions and retain their full activity for at least four runs. The yields obtained for both reactions are good to excellent. The mild operation conditions of the palladium nanoparticles are traced back to the absence of surface stabilization. Further mechanistic implications are discussed.

The use of palladium nanoparticles supported on MCM-41 mesoporous molecular sieves in Heck reaction: A comparison of basic and neutral supports

Bifunctional supported catalysts were prepared by grafting of chemically reduced palladium nanoparticles onto basic MCM-41-type solid supports. The supports were obtained by ion-exchange with Cs + or K + ions from both in-synthesis and post-synthesis Al-doped mesoporous molecular sieves MCM-41 (i.e., (Al)MCM-41 and Al-grafted MCM-41). For a comparison, Pd@Cs +-exchanged zeolite Y and the non-basic Pd@MCM-41 catalyst were also prepared. All supported catalysts were tested in Heck reaction of butyl acrylate and bromobenzene to give n-butyl cinnamate. Catalysts Pd@Cs +-(Al)MCM-41 and Pd@Cs +-Al-grafted MCM-41 proved to be superior to the analogous catalysts reported in the literature in terms of turnover number and turnover frequency. Most active, however, were catalytic systems obtained from combination of the simple, non-basic Pd@MCM-41 with an external base, which gave the coupling product in 33% after 20 h at 160 °C in N,N-dimethylacetamide in the presence of sodium acetate and at 1 mol.% palladium loading.

The electroanalytical detection of hydrazine: A comparison of the use of palladium nanoparticles supported on boron-doped diamond and palladium plated BDD microdisc array

We show that both a random distribution of palladium nanoparticles supported on a BDD electrode or a palladium plated BDD microelectrode array can each provide a sensing platform for the electrocatalytic detection of hydrazine. The palladium nanoparticle modified electrode displays a sensitivity and limit of detection of 60 mA mol(-1) L and 2.6 microM respectively while the array has a sensitivity of 8 mA mol(-1) L with a detection limit of 1.8 microM. The beneficial cost implications of using palladium nano- or micro-particles in sensors compared to a palladium macroelectrode are evident. Interestingly the array of the nanoparticles shows similar sensitivity and limit of detection to the microelectrode array which probably indicates that the random distribution of the former leads to 'clumps' of nanoparticles that effectively act as microelectrodes.