Search

Thiolate (SR) protected noble metal nanoclusters have grasped immense attention because of their promising applications in electrocatalysis, electrochemical sensors, photoluminescencse, supercapacitor and energy production. Among the noble metals, numerous reports have highlighted interesting results for Au 25 (SR) 18 , Au 22 (SR) 18 and Ag 44 (SR) 30 clusters but Pd and Pt nanoclusters are less addressed. Room temperature ionic liquids (RTIL) show enhanced electrocatalytic activity and stability as a binding matrix as compared to commercial binders like Nafion, Polyvinylidene fluoride (PVDF) and so on. Here, we have synthesised water-soluble thiolate 3-mercaptopropyl sulfonate (MPS) capped Palladium nanoclusters (Pd-MPS NCs). Further, Poly Acrylamide Gel Electrophoresis (PAGE), a separation technique was used to isolate size-dependent NCs and their electrocatalytic activity for the hydrogen evolution reaction (HER) with room temperature ionic liquid as a binding matrix was demonstrated. The electron microscope images of isolated Pd-MPS NCs from these three bands (obtained from PAGE separation) resulted with size ranges of 0.8-1.8 nm, 2-4 nm and 4.2-8 nm respectively. Among the three bands obtained from PAGE gel from the crude Pd NCs, the ultrasmall Pd m (SR) n NCs was isolated from the lower band resulted in high HER activity with less overpotential of 197 mV and a Tafel slope of 125.2 mV dec-1 as compared to Pd-MPS NCs obtained from the other two distinctive bands. [Display omitted] • A stable and water-soluble 3-mercaptopropyl sulfonate (MPS) protected atomically precise Pd nanoclusters was achieved. • As achieved Pd-MPS NCs was subjected to isolation using PAGE technique which resulted in three distinct bands of ultrasmall Pd m (SR) n NCs. • HR-TEM images of the three isolated Pd m (SR) n NCs were in the size range of 0.8-1.8 nm, 2–4 nm and 4.2-8 nm respectively. • RTIL matrix assisted Pd m (SR) n NCs exhibited tunable HER activities with lesser overpotential and Tafel slope values as compared to their larger clusters. [ABSTRACT FROM AUTHOR]

Water-soluble, stable, and monodisperse palladium nanoclusters (PdNCs) were synthesized using NaBH4 as a reductant and lipoic acid as a ligand. PdNCs, measured by high-resolution transmission electron microscopy, showed a round shape and a diameter of 2.49 ± 0.02 nm. It was found that each PdNC contains 550 Pd atoms on average. These PdNCs offer high amplification as a label of biochemical reactions when inductively coupled plasma-mass spectrometry (ICP-MS) is used as a detector. In addition, PdNCs have catalytic activity on electrochemical reactions, allowing detection by linear sweep voltammetry (LSV). As a proof of applicability, a competitive immunoassay based on PdNC labels was developed for the determination of glial fibrillary acidic protein (GFAP) in human serum, comparing ICP-MS and LSV detection. GFAP is a biomarker for differentiating between patients with ischemic stroke (IS) and hemorrhagic stroke (HS). The limit of detection (LoD), corresponding to IC10 (4-parameter logistic curve), was 0.03 pM of GFAP, both by ICP-MS and LSV, being lower than the 0.31 pM LoD provided by the ELISA commercial kit. Using the error profile method, 0.03 pM and 0.11 pM LoDs were obtained respectively by ICP-MS and LSV: LoD is lower by ICP-MS due to the better precision of the measurements. The analyses of human serum samples from IS, HS, and control (CT) donors using PdNC labels and detection by ICP-MS and LSV were validated with a commercial ELISA kit (for CT donors only ICP-MS provided enough sensitivity). Results point out toward the future use of PdNCs as a label in other immunoprobes for the determination of specific proteins requiring very low LoDs as well as the development of electrochemical decentralized methodologies. [ABSTRACT FROM AUTHOR]

The rational fabrication of Pt‐free catalysts for driving the development of practical applications in alkaline water electrolysis and fuel cells is promising but challenging. Herein, a promising approach is outlined for the rational design of multimetallic catalysts comprising multiple active sites including Pd nanoclusters and Ru single atoms anchored at the defective sites of Ni(OH)2 to simultaneously enhance hydrogen evolution reactions (HER) and ethanol oxidation reactions (EOR). Remarkably, Pd12Ru3/Ni(OH)2/C exhibits a remarkably reduced HER overpotential (16.1 mV@10 mA cm−2 with a Tafel slope of 21.8 mV dec−1) as compared to commercial 20 wt.% Pt/C (26.0 mV@10 mA cm−2, 32.5 mV dec−1). More importantly, Pd12Ru3/Ni(OH)2/C possesses a self‐optimized overpotential to 12.5 mV@10 mA cm−2 after 20 000 cycles stability test while a significantly decreased performance for commercial 20wt.% Pt/C (64.5 mV@10 mA cm−2 after 5000 cycles). The mass activity of Pd12Ru3/Ni(OH)2/C for the EOR is up to 3.724 A mgPdRu−1, ≈20 times higher than that of commercial Pd/C. Electrochemical in situ Fourier transform infrared measurements confirm the enhanced CO2 selectivity of Pd12Ru3/Ni(OH)2/C while synergistic and electronic effects of adjacent Ru, Pd, and OHad adsorption on Ni(OH)2 at low potential play a key role during EOR. [ABSTRACT FROM AUTHOR]

The transition toward hydrogen gas (H 2 ) as an eco-friendly and renewable energy source necessitates advanced safety technologies, particularly robust sensors for H 2 leak detection and concentration monitoring. Although palladium (Pd)-based materials are preferred for their strong H 2 affinity, intense palladium-hydrogen (Pd-H) interactions lead to phase transitions to palladium hydride (PdH x ), compromising sensors' durability and detection speeds after multiple uses. In response, this study introduces a high-performance H 2 sensor designed from thiolate-protected Pd nanoclusters (Pd 8 SR 16 ), which leverages the synergistic effect between the metal and protective ligands to form an intermediate palladium-hydrogen-sulfur (Pd-H-S) state during H 2 adsorption. Striking a balance, it preserves Pd-H binding affinity while preventing excessive interaction, thus lowering the energy required for H 2 desorption. The dynamic adsorption-dissociation-recombination-desorption process is efficiently and highly reversible with Pd 8 SR 16 , ensuring robust and rapid H 2 sensing at parts per million (ppm). The Pd 8 SR 16 -based sensor demonstrates exceptional stability (50 cycles; 0.11% standard deviation in response), prompt response/recovery (t 90 = 0.95 s/6 s), low limit of detection (LoD, 1 ppm), and ambient temperature operability, ranking it among the most sensitive Pd-based H 2 sensors. Furthermore, a multifunctional prototype demonstrates the practicality of real-world gas sensing using ligand-protected metal nanoclusters., (© 2024 Wiley‐VCH GmbH.)

The monomeric hemeprotein myoglobin (Mb) has immense biological importance as it is first released from damaged muscles in case of an injury. Since excessive release of Mb damages kidney and causes acute renal failure, monitoring of Mb is relevant. A novel and cost-effective fluorescence sensor for label free determination of Mb has been developed. The turn-off assay is based on methionine stabilized palladium nanoclusters (Met-PdNCs). The Met-PdNCs have been characterized by spectroscopic techniques such as fluorescence, UV–Vis spectroscopy, FTIR and microscopic technique TEM along with DLS. The quenching mechanism was attributed to the synergistic effects of agglomeration-induced quenching and inner filter effect. The developed sensor exhibited a linear range of 1.00 × 10−5 M to 8.00 × 10−7 M with a limit of detection of 1.67 × 10−7 M. The practicality of the developed Mb sensor was validated through spike recovery analysis and a classic spectrophotometric method. [ABSTRACT FROM AUTHOR]

[Display omitted] • Transfer hydrogenation under air conditions. • Green reactions based on aqueous phase. • The synergistic action of two reaction mechanisms. • No organic solvents are used in the reaction and post-treatment process. • 35 examples, 100 % selectivity, yield up to 99 %. A green synthesis of anilines by the non-hydrogen reduction of nitro compounds is described. The reaction and post-treatment purification processes can produce high-purity target products without the use of organic solvents. The key to success lies in the synergistic action of two reaction mechanisms. The hydrogen transfer system is significantly accelerated by the presence of binaphthyl-palladium nanoclusters, which permits the catalyzed selective transfer hydrogenation under air conditions, providing a general preparation of aromatic amines in good-to-high yields with excellent chemoselectivities. Benefitting from the heterogeneous manner in water, successful recycling of the catalysts was further achieved with high reaction efficiency maintained. Meanwhile, the ICP analysis results show that the residual palladium content in the target product was below 5 ppm. [ABSTRACT FROM AUTHOR]

In this study, polyaniline (PANI) with abundant protonated regions was used for the first time as a palladium (Pd) support for enhanced performance in hydrogen evolution reaction (HER). For this purpose, the hierarchical Pd@PANI nanofiber electrode was easily synthesized by electrochemical polymerization of aniline on Au followed by potential-controlled electrochemical deposition of Pd nanoclusters on the PANI. The reported catalyst was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and field-emission scanning electron microscopy. Linear sweep voltammetry analysis was performed to evaluate the HER performance. Ion transfer behavior was investigated using electrochemical impedance spectroscopy analysis. The electrochemical tests show that the Pd@PANI/Au electrode has a low overpotential of ∼60 mV at 10 mA cm−2 and a small Tafel slope of 35 mV dec−1 for HER in acidic media, with high catalytic activity and stability. These features will make the Pd@PANI/Au a promising candidate as a high-performance electrocatalyst for HER applications. [Display omitted] • Pd@PANI/Au composites was produced by a facile two-step electrochemical approach. • Pd@PANI/Au composites is studied as high performance HER electrocatalyst. • Pd@PANI/Au shows high catalytic activity and stability for HER. • Delivering low overpotential of 60 mV at 10 mA cm−2 and Tafel slope of 35 mV dec−1. [ABSTRACT FROM AUTHOR]

On the basis of the molecular dynamics results obtained by using the tight binding potential, the heats of melting, crystallization, and also the sublimation and evaporation heats of platinum and palladium nanoclusters were found. The obtained size dependences are linear if the inverse radius is chosen as an argument, which allows extrapolating the dependencies to the corresponding bulk phases and comparing with the tabulated values.

A specific structural transformation of size-selected Pd nanoclusters, from amorphous to highly symmetrical structures, is observed following catalytic reaction using aberration-corrected scanning transmission electron microscopy (AC-STEM). This surprising behaviour, which occurs concurrently with the alkyne hydrogenation reaction, is clearly size-dependent. [Display omitted] • Observation of transformation of mass-selected Palladium nanoclusters under strictly controlled chemical environment (annealing in inert gas, reduction in hydrogen atmosphere, and 1-pentyne hydrogenation). • Establish what role the reaction itself plays in driving the restructure. • Novel structural transformation on size-selected Pd nanoclusters from amorphous to highly symmetrical structures is observed. • Size-dependent transformation phenomena confirmed between Pd clusters of different size in equal treatment. Nanostructured palladium catalysts are used industrially for selective alkyne hydrogenation reactions. However, structural changes can lead to a loss of performance. In this study, we show the evolution of the atomic structure of monodispersed Pd nanoclusters undergoing a vapour-phase 1-pentyne hydrogenation reaction. A specific structural transformation, from amorphous to highly symmetrical structures, is observed at the atomic level with aberration-corrected scanning transmission electron microscopy (AC-STEM). This surprising behaviour which occurs concurrently with the alkyne hydrogenation reaction, is clearly size-dependent. The results provide new understanding of the long-term stability of commercial heterogeneous catalysts. [ABSTRACT FROM AUTHOR]

Encapsulated nanoclusters based on palladium, 12-tunstophosphoric acid and silica was designed by simple wet impregnation methodology. The catalyst was found to be very efficient towards cyclohexene hydrogenation up to five catalytic runs with substrate/catalyst ratio of 4377/1 at 50 °C as well as for alkene, aldehyde, nitro and halogen compounds. Silica encapsulated Pd nanoclusters stabilized by 12-tungstophosphoric acid is proved to be sustainable and excellent for water mediated hydrogenation reaction with very high catalyst to substrate ratio as well as TON. [ABSTRACT FROM AUTHOR]

The electronic structure of the spherical Mackay icosahedral nanosized cluster Pd55(PiPr3)12(μ3‐CO)20 is analyzed by using DFT calculations. Results reveal that it can be considered as a regular superatom with a "magic" electron count of 20, characterized by a 1S2 1P6 1D10 2S2jellium configuration. Its open shell nature is associated with partial occupation of non‐jellium, 4d‐type, levels located on the interior of the Pd55 kernel. This shows that the superatom model can be used to rationalize the bonding and stability of spherical ligated group 10 clusters, despite their apparent 0‐electron count. [ABSTRACT FROM AUTHOR]

Nonenzymatic sensors based on a metals nanocomposite with high sensitivity, selectivity, and stability has been received considerable interest. In this study, a novel electrochemical nanocomposite sensor based on palladium nanoclusters (PdNCs) decorated electrochemically activated graphene (EAGr) was established for highly sensitive nonenzymatic H2O2 sensor. The PdNCs/EAGr nanocomposite was fabricated via an electrochemical activation of Gr by the potential cycling in the range of +0.6 to −1.8 V, followed by the electrodeposition of PdNCs at −0.4 V applied potential. The homogeneous dispersion of PdNCs/EAGr nanocomposite were characterized by scanning electron microscopy (SEM), X‐ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and linear sweep voltammetry (LSV). The PdNCs/EAGr nanocomposite electrode showed higher electrocatalytic activity towards the reduction of H2O2 in pH 7.0 of 0.1 M PBS by significantly enhancing the reduction peak current and reduced the reduction overpotential as well as eliminated other interfering species responses. The PdNCs/EAGr electrode displayed a wide linear range for H2O2 reduction from 1.0 to 1100 μM with limit of detection 0.02±0.01 μM. The higher sensitivity and selectivity as well as long‐time stability and excellent reproducibility obtained, indicating the proposed sensor is an effective H2O2 based sensor. In addition, the analytical application of the nancomposite sensor was successfully examined for the determination of H2O2 in the real sample of human urine indicating that the appreciable practicality of the nonenzymatic sensor for the determination of H2O2 in physiological fluids. [ABSTRACT FROM AUTHOR]

Abstract This paper develops a simple and green process of synthesizing palladium nanoclusters (PdNCs) capped on the hybrid nanocomposite based on biodegradable polysaccharides, 2-hydroxypropyl-β-cyclodextrin (HPCD) and alginate (Alg) through an ionotropic gelation mechanism. PdNCs were biosynthesized from aqueous extract of Burdock root (BR), Arctium lappa. The nanocomposite PdNCs/HPCD/Alg was characterized by techniques like UV–Vis, FTIR, EDX, FESEM, TEM, HR-TEM and TG-DTA. The crystal palladium nanoparticles were found to distribute in cluster shape with a size of 4–10 nm. EDX data showed that average amount of palladium capped on the hybrid nanocomposite was approx. 4.7% (w/w). PdNCs/HPCD/Alg exhibited highly catalytic activity for degradation of pollutants including 4-nitrophenol, methyl orange and rhodamine B in wastewater and leaching mechanism of the nanocatalyst was showed. In particular, the nanocomposite showed excellent aqueous-phase catalytic performance for free-triphenylphosphine Sonogashira cross-coupling reaction. The nanocatalyst could be efficiently reused without much compromising with its activity. Graphical abstract Unlabelled Image Highlights • Biogenic PdNCs/HPCD/Alg first synthesized by aqueous extract of Arctium lappa • Characterization of the nanocomposite determined by modern analytic technology • Recyclable catalytic activity of PdNCs performed for degradation of pollutants • Recyclable catalytic activity of PdNCs performed for Sonogashira reaction in water [ABSTRACT FROM AUTHOR]

[Display omitted] • Small size Pd nanocluters (2–5 nm) can accelerate the reaction kinetics and have superior catalytic effect. • The Pd nanoclusters and the sulfur vacancy on the substrate have synergistic effect to enhance the catalytic ability for HER. • The catalyst in the form of metal-supported achieves low overpotential (25 mV vs. RHE) at 10 mA cm−2 and high stability. Hydrogen energy is regarded as the clean energy alternative for fossil energy. Hydrogen evolution reaction (HER) is a sustainable way for the production of hydrogen energy. However, commercial platinum (Pt) catalysts for HER are expensive and scarce, which will not fully meet the demand of the future market. Therefore, scientists have been actively exploring alternatives to Pt-based catalysts. Studies have shown that palladium (Pd) and Pt have similar catalytic activity in HER. Small molecular Pd nanoclusters can be used as a perfect HER activity center. Herein, anchoring of Pd nanoclusters (Pd NCs) on sulfur-vacancy-enriched ZnIn 2 S 4 nanosheets (Pd/ZIS-T) has been successfully achieved. The zeta potential value for ZnIn 2 S 4 is −59.9 mV, indicating that the surface of ZnIn 2 S 4 is abundant negatively charged in deionized water, thus providing plentiful anchoring sites to absorb Pd2+. The results show that the synergistic effect of Pd NCs and sulfur vacancies will endow the obtained catalyst with excellent electrocatalytic activity and stability. It also managed to reducing costs by reducing noble metal content. In particular, the Pd/ZIS-T electrocatalyst with excellent performance delivered low overpotential of 25 mV at 10 mA cm−2 and small Tafel slope of 33 mV dec-1 in acidic electrolyte. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide is a low-reactivity reactive oxygen species (ROS); however, it can easily penetrate cell membranes and produce highly reactive hydroxyl radical species through Fenton’s reaction. Its presence in abnormal amounts can lead to serious diseases in humans. Although the development of a simple, ultrasensitive, and selective method for H2O2 detection is crucial, this remains a strategic challenge. The peroxidase mimetic activity of palladium nanoclusters (PdNCs) has not previously been evaluated. In this study, we developed an ultrasensitive and selective colorimetric detection method for H2O2 using PdNCs. An unprecedented eco-friendly, cost-effective, and facile biological method was developed for the synthesis of PdNCs. This is the first report of the biosynthesis of PdNCs. The synthesized nanoclusters had a significantly narrow size distribution profile and high stability. The nanoclusters were demonstrated to possess a peroxidase mimetic activity that could oxidize peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB). Various interfering substances in serum (100 μM phenylalanine, cysteine, tryptophan, arginine, glucose, urea, Na+, Fe2+, PO43−, Mn+2, Ca2+, Mg2+, Zn2+, NH4+, and K+) were included to evaluate the selectivity of the assay, and oxidation of TMB occurred only in the presence of H2O2. Therefore, PdNCs show an efficient nanozyme for the peroxidase mimetic activity. The assay produced a sufficient signal at the ultralow concentration of 0.0625 µM H2O2. This colorimetric assay provides a real-time, rapid, and easy-to-use platform for the detection of H2O2 for clinical purposes.

Atomically precise monodisperse palladium nanoclusters protected by N -acetyl- l -cysteine (Pd n (NALC) m ) ligand were synthesized. Protected nanoclusters block the mesoporous pores of supports and decrease their specific surface area after loading with 1 wt % as found in our previous work. The new synthesized palladium clusters with special crystal structure did not block the mesoporous pores of iron oxide support (α-Fe 2 O 3 ). Moreover, the pore volume and pore diameter of the support was increased by synthesizing palladium clusters with 1 wt % dopant. The doped catalyst was irradiated by microwave synthesis labstation 1 h at 80 °C and 500 W to gently remove of the protected N -acetyl- l -cysteine ligands and produce bare palladium clusters supported on iron oxide. The particles size of the synthesized palladium clusters was investigated by high resolution transmission electron microscope (HRTEM). The spectroscopic properties and chemical composition of Pd n (NALC) m clusters were studied by UV-vis spectroscopy and thermogravimetric analysis (TGA), elemental analysis and atomic absorption spectroscopy. FTIR was used for the free ligand (NALC) and the protected palladium cluster, where the disappearance of the S–H vibrational band at 2535–2570 cm −1 in the palladium clusters spectrum confirmed the ligand is anchored to the cluster surface through the sulfur atom. The crystallinity of the bare iron oxide and the doped palladium clusters (1%Pd n (NALC) m /α-Fe 2 O 3 ) and the microwave treated catalyst (1% Pd n /α-Fe 2 O 3 ) were determined by powder X-ray diffraction analysis. BET surface area, pore volume and average pore diameter were investigated via nitrogen adsorption at −196 °C. The catalytic properties of atomically precise palladium nanoclusters supported on iron oxide were investigated for reduction of cinnamaldehyde as example for α,β-unsaturated aldehydes. The catalytic activity of synthesized catalysts increased in this order 1% Pd n /α-Fe 2 O 3 > 1% Pd n (NALC) m /α-Fe 2 O 3 > Pd n (NALC) m . The catalytic reduction reaction in toluene was performed at temperature 20–80 °C. The aforementioned synthesized catalysts showed 100% chemoselectivity in the reduction of cinnamaldehyde at room temperature. [ABSTRACT FROM AUTHOR]

Metal nanoclusters, with dimensions between atomic and nanoparticles, have attracted a great deal of attention due to their significantly unusual properties. Water-soluble palladium nanoclusters (Pd NCs) with blue-green fluorescence were synthesized by a water bath heating method, with methionine as a stabilizer and ascorbic acid as a reducing agent. We investigated the optimal synthesis conditions, stability, and pH response of the obtained products in detail. The synthesized materials were characterized by ultraviolet-absorption spectroscopy, fluorescence spectroscopy, high-resolution transmission electron microscopy, and atomic force microscopy. These experimental results showed that the Pd NCs had a small size of ~1.91 nm, with a uniform size distribution. Additionally, the Pd NCs emitted blue-green fluorescence under ultraviolet light with a quantum yield of 5.47%. Notably, both stabilizers and reducing agents used in this synthesis method are nutrients for humans, non-toxic, and harmless. This method could be viewed as a biologically friendly and green way of preparing fluorescent metal nanoclusters. The as-prepared fluorescent Pd NCs also possessed excellent fluorescence detection ability and were very sensitive to low concentrations of hemoglobin, with a linear response in the range of 0.25–3.5 μM and a detection limit of 50 nM. [ABSTRACT FROM AUTHOR]

Ultrasmall noble-metal nanoclusters have been gaining extensive attention because of their unique catalytic activity. Herein, we describe a facile in situ method for the preparation of palladium nanoclusters encapsulated in porous carbon nanosheets as effective catalysts for the oxygen reduction reaction (ORR) in alkaline media. Structural characterizations through X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy studies indicate that the Pd clusters were well incorporated into porous carbon nanosheets. The composition of the nanocomposites was manipulated by varying the initial loading ratio of Pd to carbon nanosheets (Pd/CNS). Among the series of samples tested, the sample at a Pd/CNS ratio of 1 : 4 (Pd/CNS-20 %) exhibited the best ORR activity with the most positive onset potential and largest diffusion-limited current density, which was even superior to that of commercial Pd black, along with remarkable long-term durability. The findings highlight the unique advantages of employing ultrasmall ligand-free palladium clusters as cost-effective ORR catalysts with high efficiency and remarkable stability. [ABSTRACT FROM AUTHOR]

Herein, we synthesized some ultra small silver nanoclusters (AgNCs) and palladium nanoclusters (PdNCs) protected by L -glutathione (L-GSH) reduced ligand to study their antimicrobial properties in the visible and dark conditions. These clusters can be dissolved, dried, and redissolved in water without suffering from any agglomeration or degradation. The particles sizes of the synthesized nanoclusters were around 1 nm, which investigated by high-resolution transmission electron microscopy (HRTEM). The optical properties of the synthesized nanoclusters were studied by UV–vis spectroscopy. Ag n (SG) m clusters exhibited two plasmon peaks in the visible region at 478 and 641 nm. However, Pd n (SG) m clusters showed a steep rise absorption in the short wavelength range of the spectrum and featureless in the visible region. Fourier transform infrared spectroscopy (FTIR) was measured for the free ligand and protected clusters Ag n (SG) m and Pd n (SG) m . Compared with palladium nanoclusters (in vitro), silver nanoclusters exhibited higher biocidal activity (MIC). The influence of silver and palladium nanoclusters (0.0, 2.5, 3.5, 5.0, 8.0 mg/l) on soil fungal community density was investigated under dark and light condition. Interestingly, silver NPs were more effective than palladium nanoclusters. Moreover, silver NPs were more effective in light than in the dark. However, palladium nanoclusters showed more or less similar effect under both contrasting conditions. This might be attributed to the disappearance of the plasmonic effect of palladium clusters in the UV–vis region. The novelty of our method is due to using ligand (L-GSH) as a capping agent with palladium. Besides, l -glutathione is considered as a part of the microbial system to detoxify metals. This guarantees the safety of the synthesized nanoparticles to be applied commercially than the naked isotopes. These nanoclusters could be considered a basic unit for medicine industry such as drug delivery tools or applied in paints industry (antimicrobial agents). [ABSTRACT FROM AUTHOR]

Highly dispersed palladium nanoclusters incorporated on amino-functionalized silica sphere surfaces (Pd/SiO2-NH2) were fabricated by a simple utilizing 3-(2-aminoethylamino)propyltrimethoxysilane (AAPTS) as coordinating agent. Uniform palladium nanoclusters with an average size of 1.1 nm can be obtained during the co-condensation of tetraethyl orthosilicate and AAPTS owing to the strong interaction between palladium species and amino groups in AAPTS. The palladium particle size can be controlled by addition of AAPTS and plays a significant role in the catalytic performance. The Pd/SiO2-NH2 catalyst exhibits high for succinic acid with 100% conversion and 94% selectivity towards γ-butyrolactone using 1,4-dioxane as solvent at 240°C and 60 bar for 4 h. Moreover, the Pd/SiO2-NH2 catalyst is robust and readily reusable without loss of its . Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this study, a post-annealing-free, adhesive nickel/phosphorous (Ni/P) layer was deposited on a 3-[2-(2-aminoethylamino)ethylamino] propyl-trimethoxysilane-modified (ETAS-modified) silicon (Si) surface through an electroless deposition process catalyzed by a novel polyvinylpyrrolidone-capped palladium nanocluster (PVP-nPd). ETAS was covalently bonded on the Si surface, whereas the amino groups on ETAS bridged with the palladium core in the PVP-nPd clusters. Because of the mentioned two effects, the deposited Ni/P layer showed superior adhesion on the Si wafer without the requirement of conventional annealing treatment. Compared with the Ni/P films deposited on bare and ETAS-modified Si surfaces by using commercial Sn/Pd colloids, the adhesion of the Ni/P film catalyzed by PVP-nPd on the ETAS-modified Si wafer improved 4- and 2-fold, respectively. [ABSTRACT FROM AUTHOR]

Abstract: Palladium(0) nanoclusters stabilized by poly(4-styrenesulfonic acid-co-maleic acid), PSSA-co-MA, were generated in situ during the hydrolysis of ammonia–borane (AB) from the reduction of potassium tetrachloropalladate(II) in aqueous solution at room temperature. They were isolated from the reaction solution and characterized by UV–visible electronic absorption spectroscopy, TEM, SAED and XRD techniques. The PSSA-co-MA stabilized palladium(0) nanoclusters were used as catalyst in Suzuki–Miyaura cross-coupling reactions of various of arylbromides or aryl iodide with phenylboronic acid in water without any purification process after catalytic hydrolysis of AB. They show excellent catalytic activity in coupling of series of aryl bromides or aryl iodide with phenylboronic acid under the optimized reaction conditions in water. PSSA-co-MA stabilized palladium(0) nanoclusters provided turnover frequency of 1980 and 5940h−1 in Suzuki–Miyaura coupling reactions of phenylboronic acid with p-bromoacetophenone or p-iodobenzene, respectively, which are the highest values ever reported for the Suzuki–Miyaura coupling reactions in water as sole solvent. [Copyright &y& Elsevier]

Preparation of the catalyst has been performed using the direct reaction between the multi-walled carbon nanotubes and zerovalent palladium complex with the easily removed ligand, dibenzylideneacetone, dba. TEM microphotos have been obtained and metal particles dimension measured. Coupling reactions of Suzuki-Miyaura, Heck and Sonogashira are efficiently catalyzed by this catalyst as well as hydrogenation of the triple carbon-carbon bond. The catalyst is re-usable and can work in aqueous media. [ABSTRACT FROM AUTHOR]

Abstract: Palladium (Pd) and palladium–platinum (Pd–Pt) colloidal nanoclusters catalysts have been prepared and immobilized on a magnetic support. Modification effects of magnetic support Fe3O4 and bimetallic structure on the catalysts have been studied by catalytic experiments and computational simulation. The Fe3O4 support benefits to catalytic selectivity of the nanoclusters in the selective hydrogenation of o-chloronitrobenzene to o-chloroaniline. X-ray photoelectron spectroscopy analyses indicate that the interaction between Fe3O4 and Pd atoms modifies catalytic performances of the nanoclusters. Computational simulation gives the atom distribution, in which Pd atoms are enriched on the surface of the Pd–Pt bimetallic cluster, while Pt atoms on the subsurface. It is found that the inner Pt atoms present beneficial modification on catalytic selectivity. In conclusion, the magnetic metal nanocluster catalysts provide good catalytic properties and easy isolation by magnetic field for their reuse. [Copyright &y& Elsevier]

Four lipophilic polystyrene–methacryloylethylensulfonic acid–divinylbenzene gel-type resins, with 2 and 4% cross-linking degree, are synthesized and used as supports for “atomic” dispersion of Pd(II) finalized to the preparation of resins-supported palladium metal catalysts. Properly performed reduction of Pd(II) to Pd(0) achieves homogeneous dispersion of ca. 3 nm metal nanoclusters inside the supports particles in the more cross-linked resin. Resulting resin-supported palladium catalysts are efficient and moderately chemoselective in the hydrogenation of 2-ethylanthraquinone to 2-ethylanthrahydroquinone. [Copyright &y& Elsevier]

Hydroxy-CNT were modified with optically active α-amino acids. The resulting chiral derivatives were directly palladated with Pddba and used to catalyze the hydrogenation of α-acetamidostyrene and α-phenylcinnamic acid as well as the hydroarylation of norbornene with iodoarenes. All the catalytic reactions afforded products containing a new chiral carbon center in high yields, though as racemates. Apparently, asymmetric induction is precluded because the palladium sites on the CNT surface are spatially apart from the chiral carbon centers in amino acid groups. [ABSTRACT FROM AUTHOR]

Single-walled carbon nanotube (SWCNT) functionalized with Pd nanoclusters have been shown experimentally to be effective H2S gas sensors. To this end, we have modeled a field-effect transistor with semiconducting SWCNT functionalized with palladium nanoclusters as the channel. Using non-equilibrium Green's function method combined with density functional theory, we have investigated the effect of Pd nanoclusters on the electrical properties of the device and the sensing ability of the device as an H2S gas sensor at zero bias voltage. We have modeled two devices, one with Au electrodes and the other with SWCNT electrodes to show the effect of Au electrodes on the electrical properties of the device. In order to analyze the reason for the changes in the electrical properties of the device, charge transfer and electrostatic potential of the system are investigated. Results show that in both devices, functionalization with Pd nanoclusters results with the accumulation of charge on the channel while H2S adsorption causes charge depletion in the channel. In all cases, both charge transfer and electrostatic gating are responsible for the changes in the charge-carrier concentration in the channel. Due to significant changes in the electrical properties of the device after H2S adsorption, detection is possible with high sensitivity. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide is a low-reactivity reactive oxygen species (ROS); however, it can easily penetrate cell membranes and produce highly reactive hydroxyl radical species through Fenton's reaction. Its presence in abnormal amounts can lead to serious diseases in humans. Although the development of a simple, ultrasensitive, and selective method for H2O2 detection is crucial, this remains a strategic challenge. The peroxidase mimetic activity of palladium nanoclusters (PdNCs) has not previously been evaluated. In this study, we developed an ultrasensitive and selective colorimetric detection method for H2O2 using PdNCs. An unprecedented eco-friendly, cost-effective, and facile biological method was developed for the synthesis of PdNCs. This is the first report of the biosynthesis of PdNCs. The synthesized nanoclusters had a significantly narrow size distribution profile and high stability. The nanoclusters were demonstrated to possess a peroxidase mimetic activity that could oxidize peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB). Various interfering substances in serum (100 μM phenylalanine, cysteine, tryptophan, arginine, glucose, urea, Na+, Fe2+, PO43−, Mn+2, Ca2+, Mg2+, Zn2+, NH4+, and K+) were included to evaluate the selectivity of the assay, and oxidation of TMB occurred only in the presence of H2O2. Therefore, PdNCs show an efficient nanozyme for the peroxidase mimetic activity. The assay produced a sufficient signal at the ultralow concentration of 0.0625 µM H2O2. This colorimetric assay provides a real-time, rapid, and easy-to-use platform for the detection of H2O2 for clinical purposes. [ABSTRACT FROM AUTHOR]

Herein, we report on the synthesis of ultrasmall Pd nanoclusters (∼2 nm) protected by L-cysteine [HOCOCH(NH 2 )CH 2 SH] ligands (Pd n (L-Cys) m ) and supported on the surfaces of CeO 2 , TiO 2 , Fe 3 O 4 , and ZnO nanoparticles for CO catalytic oxidation. The Pd n (L-Cys) m nanoclusters supported on the reducible metal oxides CeO 2 , TiO 2 and Fe 3 O 4 exhibit a remarkable catalytic activity towards CO oxidation, significantly higher than the reported Pd nanoparticle catalysts. The high catalytic activity of the ligand-protected clusters Pd n (L-Cys) m is observed on the three reducible oxides where 100 % CO conversion occurs at 93-110 °C. The high activity is attributed to the ligand-protected Pd nanoclusters where the L-cysteine ligands aid in achieving monodispersity of the Pd clusters by limiting the cluster size to the active sub-2-nm region and decreasing the tendency of the clusters for agglomeration. In the case of the ceria support, a complete removal of the L-cysteine ligands results in connected agglomerated Pd clusters which are less reactive than the ligand-protected clusters. However, for the TiO 2 and Fe 3 O 4 supports, complete removal of the ligands from the Pd n (L-Cys) m clusters leads to a slight decrease in activity where the T 100% CO conversion occurs at 99 °C and 107 °C, respectively. The high porosity of the TiO 2 and Fe 3 O 4 supports appears to aid in efficient encapsulation of the bare Pd n nanoclusters within the mesoporous pores of the support., (© 2020 Wiley-VCH GmbH.)