PdRu Nanoparticles Research Articles

C3N4 modified PdO-Ru-functionalized ZnO long-grained nanoparticles for fast detection of ppb-level triethylamine

Triethylamine is a vital chemical raw material, but its leakage will pollute the environment and harm human health. It is particularly important to achieve detection of triethylamine. Here, PdRu nanoparticles, ZnO long-grained nanoparticles and C3N4 were prepared for the identification of low concentrations of triethylamine. The response value of the sensor based on PdO-Ru/ZnO-C3N41 to 20 ppm triethylamine was 96 at 220 °C. Furthermore, the lowest detection amount of it was as low as 50 ppb. And the time for rapid detection of 20 ppm triethylamine was shown to be 1 s. Besides, a circuit was designed to detect triethylamine in real time and raise the alarm when the concentration of triethylamine exceeded a threshold. The catalytic ability of PdRu nanoparticles and the formation of n-n heterojunction between ZnO and C3N4 were conducive to enhancing the sensing performance. This work provides a way for monitoring of triethylamine and timely warning in chemical plants.

PdRu/SBA15 catalysts for hydrogen storage by reversible N-ethylcarbazole hydrogenation/dehydrogenation reactions

In this work, a stable double complex salt (DCS) on the surface of SBA-15 is constructed by phase transfer-assisted electrostatic adsorption method. DCS was then reduced by glow discharge plasma to obtain SBA-15 loaded PdRu bimetallic catalysts (PdRu/SBA15). The catalysts were characterized by nitrogen adsorption–desorption, TEM, FT-IR, XPS, H2-TPR and ICP-OES. The Pd anion dissolved by phase transfer is precisely adsorbed on the Ru cation, and this unique intimacy of two metals promotes the formation of stable structure. The synergistic effect of the DCS structure and the in-situ reduction of glow discharge plasma makes PdRu/SBA15 have highly dispersed and stable PdRu nanoparticles (NPs). PdRu/SBA15 is suitable for reversible hydrogen storage system. It not only catalyzed N-ethylcarbazole (NEC) hydrogenation efficiently, but also showed enhanced catalytic performance in the dehydrogenation of dodecahydro-N-ethylcarbazole (12H-NEC). The hydrogenation efficiency reached 99.8% for 80 min at 100 °C, H2 pressure of 5 Mpa and the dehydrogenation efficiency reached 100% for 6 h at 180 °C under the action of the same PdRu/SBA15 catalyst. Moreover, the catalytic activity of PdRu/SBA15 catalyst did not decrease obviously after seven cycles in reversible hydrogen storage. The reversible hydrogen storage PdRu catalysts with excellent activity has a very bright prospect in the practical application of fuel cells.

An ultrasensitive dietary caffeic acid electrochemical sensor based on Pd-Ru bimetal catalyst doped nano sponge-like carbon

Caffeic acid (CA) is widely present in the human daily diet, and a reliable CA detection method is beneficial to food safety. Herein, we constructed a CA electrochemical sensor employing a glassy carbon electrode (GCE) which was modified by the bimetallic Pd-Ru nanoparticles decorated N-doped spongy porous carbon obtained by pyrolysis of the energetic metal–organic framework (MET). The high-energy bond N-NN in MET explodes to form N-doped sponge-like carbon materials (N-SCs) with porous structures, boosting the adsorptive capacity for CA. The addition of Pd-Ru bimetal improves the electrochemical sensitivity. The linear range of the PdRu/N-SCs/GCE sensor is 1 nM-100 nM and 100 nM-15 μM, with a low detection limit (LOD) of 0.19 nM. It has a high sensitivity (55 μA/μM) and repeatability. The PdRu/N-SCs/GCE sensor has been used to detect CA in actual samples of red wine, strawberries, and blueberries, providing a novel approach for CA detection in food analysis.

Quantitative Characterization of the Thermally Driven Alloying State in Ternary Ir-Pd-Ru Nanoparticles.

Compositional and structural arrangements of constituent elements, especially those at the surface and near-surface layers, are known to greatly influence the catalytic performance of alloyed nanoparticles (NPs). Although much research effort often focuses on the ability to tailor these important aspects in the design stage, their stability under realistic operating conditions remains a major technical challenge. Here, the compositional stability and associated structural evolution of a ternary iridium-palladium-ruthenium (Ir-Pd-Ru) nanoalloy at elevated temperatures have been studied using interrupted in situ scanning transmission electron microscopy and theoretical modeling. The results are based on a combinatory approach of statistical sampling at the sub-nanometer scale for large groups of NPs as well as tracking individual NPs. We find that the solid solution Ir-Pd-Ru NPs (∼5.6 nm) evolved into a Pd-enriched shell supported on an alloyed Ir-Ru-rich core, most notably when the temperature exceeds 500 °C, concurrently with the development of expansive atomic strain in the outer surface and subsurface layers with respect to the core regions. Theoretically, we identify the weak interatomic bonds, low surface energy, and large atomic sizes associated with Pd as the key factors responsible for such observed features.

Highly sensitive detection of anti-cancer drug based on bimetallic reduced graphene oxide nanocomposite

Herein, we describe a high-performance electrochemical sensor for the detection of regorafenib (REG) using bimetallic Pd–Ru nanoparticles anchored on pomegranate peel extract (PPE) derived reduced graphene oxide (Pd–Ru/rGO). PPE was employed to neutralize the extremely acidic graphene then cast-off along with the metal precursor for the duration of the chemical reduction to accomplish well dispersed Pd–Ru nanoparticles. Bimetallic Pd–Ru/rGO nanocomposites were synthesized using a facile chemical reduction method. Under optimal conditions, based on the differential pulse voltammetric studies it has been confirmed that the fabricated sensors has good electrocatalytic activity toward the detection of REG, spanning over the linear dynamic range of 0.5–300 nM. Moreover, the sensor exhibited a low limit of detection of 1.6 nM and a limit of quantification of 4.8 nM. The electrochemical sensor unveiled admirable selectivity and sensitivity, reproducibility, and repeatability. The fabricated sensor was suitable for real sample analysis (pharmaceutical tablet, human blood plasm, wastewater) with satisfactory recovery. The strategy presented herein can be employed in the development of electrochemical sensors for other target analytes.

Investigation of Local Structure and Enhanced Thermal Stability of Ir-Doped PdRu Nanoparticles for Three-Way Catalytic Applications

The local structure and thermal stability of newly synthesized PdRuIr and PdRu alloy nanoparticles (NPs) were studied using X-ray absorption fine structure spectroscopy (XAFS) and compared with those of Ru NPs. Pd K-edge XAFS reveals that a significant fraction of Pd segregates, forming metal NP clusters. In the PdRuIr NPs, a small fraction of Pd forms an alloy with Ir, whereas a majority phase is Ru–Ir alloy having the novel face-centered cubic structure. Apart from the distinct local surroundings, XAFS analysis revealed the presence of an anharmonic disorder in the PdRu and PdRuIr NPs. The previously observed enhanced thermal stability with Pd and Ir doping was investigated using temperature-dependent in situ XAFS. In the Ru NPs, an abrupt change in the near-edge features was observed at 673 K, which was gradually suppressed for PdRu and PdRuIr NPs. At this temperature, the dynamical fluctuations were more pronounced in the pure Ru NPs, helping to convert surface-adsorbed O2 into the volatile RuO4 phase, thereby leading to earlier evaporation of Ru. Dynamical fluctuation suppresses with alloying elements or gets extended to a higher temperature, helping to delay the RuO4 formation process and enhancing the thermal stability of the PdRu and PdRuIr NPs in increasing order.

Ultrafine PdRu Nanoparticles Immobilized in Metal–Organic Frameworks for Efficient Fluorophenol Hydrodefluorination under Mild Aqueous Conditions

Ultrafine PdRu Nanoparticles Immobilized in Metal–Organic Frameworks for Efficient Fluorophenol Hydrodefluorination under Mild Aqueous Conditions

PdRu Nanoparticles Supported on Functionalized Titanium Carbide—a Highly Efficient Catalyst for Formic Acid Electro-Oxidation

PdRu Nanoparticles Supported on Functionalized Titanium Carbide—a Highly Efficient Catalyst for Formic Acid Electro-Oxidation

Synergistic enhancement of activity towards hydrogen oxidation reaction by Palladium–Ruthenium bimetallic catalysts in acidic media

The hydrogen oxidation reaction (HOR) activity of PdRu bimetallic catalysts in acidic media is first investigated by preparing PdRu nanoparticles of various compositions (Pd:Ru atomic ratios of 1:0, 9:1, 3:1, 1:1, 1:9, 1:20 and 0:1) supported on carbon supports. Pd is under compressive strain when Pd and Ru atoms are alloyed, and PdRu(1:1) forms phase-separated nanoparticles. The crystallite size of PdRu/C can be reduced to ∼4 nm depending on the PdRu composition. While Ru/C shows a slightly faster HOR kinetics than Pd/C, the introduction of Ru to Pd improves the HOR kinetics leading to the highest kinetic current on PdRu9/C. The kinetic current and single-cell performance of PdRu9/C is comparable to those of commercial PtRu/C. First-principle calculations based on density functional theory indicate that the most stable position of the Pd atom is the 1st layer of the surface, which represents the possibility of surface segregation of Pd atoms. The theoretical calculations clearly unravel that the presence of strong electronic effect owing to Ru alloying with Pd, which would correspond to an optimum composition of PdRu9/C in the experiments, demonstrates a superior hydrogen oxidation activity to the other PdRu compositions.

Effect of support acidity during selective hydrogenolysis of glycerol over supported palladium-ruthenium catalysts.

We report the role of the acidity of support during the selectivity hydrogenolysis of glycerol over supported bimetallic palladium-ruthenium (PdRu) catalysts. The PdRu nanoparticles were supported on a series of metal oxides and zeolitic supports via the modified impregnation method and tested for the liquid-phase hydrogenolysis of glycerol using gaseous hydrogen. The relative acid site densities of selected catalysts were determined by ammonia temperature-programmed desorption and pyridine desorption experiments. Based on these studies, we report a direct correlation between the catalytic activity (conversion and 1,2 propane diol yield) and two different acid sites (strong acid sites and very strong acid sites). Besides zeolite-supported catalysts, TiO2 supported PdRu nanoparticles exhibit moderate catalytic activity; however, this catalyst shows high selectivity for the desired C-O bond cleavage to produce C3 products over the undesired C-C bond cleavage to produce < C3 products. This article is part of a discussion meeting issue 'Science to enable the circular economy'.

Revealing the Formation Mechanism of Alloyed Pd-Ru Nanoparticles: A Conversion Measurement Approach Utilizing a Microflow Reactor.

The synthesis of alloyed nanoparticles has been studied extensively; however, the formation mechanisms involved remain unclear. Here, we reveal the detailed formation mechanism of alloyed nanoparticles in a Pd-Ru system, using a semibatch polyol method in which the simultaneous rapid reduction of both precursors was assumed to be the critical mechanism. We employed a microflow reactor to realize rapid heating and cooling. A significant difference in the reaction rate between the two precursors was observed. Pd was reduced within seconds, but the reduction of Ru was 2 orders of magnitude slower than that of Pd and was not as rapid as previously assumed. Further investigation of the semibatch method was performed to trace changes in the particle sizes and composition. Through quantitative and multilateral evidence, we concluded that the formation of low-crystallinity seeds, followed by solid-state diffusion, is the governing mechanism for the formation of alloyed Pd-Ru nanoparticles.

Correlation between the electronic/local structure and CO-oxidation activity of Pd x Ru1-x alloy nanoparticles.

PdxRu1−x nanoparticles (NPs) were observed to display enhanced CO oxidation activity with the maximum performance obtained at the composition x = 0.5. To unveil the origin of this superior CO oxidation activity, we investigated the local structure, valence state, and electronic properties of PdxRu1−x NPs using synchrotron-based X-ray techniques. Site specific information obtained from X-ray absorption fine structure (XAFS) spectroscopy revealed that the local disorder around Pd and Ru atoms and their valence state can be systematically tuned by varying the Pd composition. Furthermore, the XAFS results indicated a strong correlation among the structural and valence state and the observed CO oxidation catalytic properties of PdxRu1−x NPs. Hard X-ray photoelectron spectroscopy (HAXPES) analysis suggested that the capability of CO oxidation requires an optimum balance between the adsorption and desorption energy for CO adsorption and eventually conversion to CO2. A comparison between the experimental valence band (VB) HAXPES spectra of PdxRu1−x NPs and the linear combination of VB HAXPES spectra of Pd and Ru NPs revealed that the charge transfer from Pd to Ru occurs in the PdxRu1−x alloy at intermediate compositions, causing electron enrichment of the Ru surface. In addition, the maximum red-shift in the edge-position relative to that of bulk Pd/Ru and high structural disorder were observed for the PdRu alloy at the intermediate composition. This coupled behavior of structure and electronic properties followed the experimental trend of CO oxidation activity in this system.

Cubic-Core Hexagonal-Branch Mechanism To Synthesize Bimetallic Branched and Faceted Pd-Ru Nanoparticles for Oxygen Evolution Reaction Electrocatalysis.

A major synthetic challenge is to make metal nanoparticles with nanosized branches and well-defined facets for high-performance catalysts. Herein, we introduce a mechanism that uses the growth of hexagonal crystal structured branches off cubic crystal structured core nanoparticles. We control the growth to form Pd-core Ru-branch nanoparticles that have nanosized branches with low index Ru facets. We demonstrate that the branched and faceted structural features of the Pd-Ru nanoparticles retain high catalytic activity while also achieving high stability for the oxygen evolution reaction.

Oxygen Reduction Reaction and Hydrogen Evolution Reaction Catalyzed by Pd–Ru Nanoparticles Encapsulated in Porous Carbon Nanosheets

Developing bi-functional electrocatalysts for both oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) is crucial for enhancing the energy transfer efficiency of metal–air batteries and fuel cells, as well as producing hydrogen with a high purity. Herein, a series of Pd–Ru alloyed nanoparticles encapsulated in porous carbon nanosheets (CNs) were synthesized and employed as a bifunctional electrocatalyst for both ORR and HER. The TEM measurements showed that Pd–Ru nanoparticles, with a size of approximately 1–5 nm, were uniformly dispersed on the carbon nanosheets. The crystal and electronic structures of the PdxRu100−x/CNs series were revealed by powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The as-prepared samples exhibited effective ORR activity in alkaline media and excellent HER activity in both alkaline and acid solutions. The Pd50Ru50/CNs sample displayed the best activity and stability among the series, which is comparable and superior to that of commercial 10% Pd/C. For ORR, the Pd50Ru50/CNs catalyst exhibited an onset potential of 0.903 V vs. RHE (Reversible Hydrogen Electrode) and 11.4% decrease of the current density after 30,000 s of continuous operation in stability test. For HER, the Pd50Ru50/CNs catalyst displayed an overpotential of 37.3 mV and 45.1 mV at 10 mA cm−2 in 0.1 M KOH and 0.5 M H2SO4, respectively. The strategy for encapsulating bimetallic alloys within porous carbon materials is promising for fabricating sustainable energy toward electrocatalysts with multiple electrocatalytic activities for energy related applications.

The Enhancement of Hydrogen Oxidation Activity and the Optimization of Alloy Composition in PdRu Nanoparticle Catalysts

Fuel cells are believed as promising power sources with many advantages including their high efficiency and environment-friendliness. Proton exchange membrane fuel cells (PEMFCs), of which usage can be expected as power sources as automobiles and so on, have yet several problems to resolve for the commercialization. Among them, the high price due to the scarcity of Pt, which is used as anode and cathode catalysts, is one of the most serious issues. Pd is a natural choice to replace Pt because the hydrogen oxidation reaction (HOR) activity of Pd is the next to that of Pt, and Pd is at least fifty times more abundant on earth than Pt. Pd is a more attractive substitute for Pt because of its higher intrinsic CO tolerance than Pt, especially as HOR catalysts for PEMFC where the tolerance of CO, a major impurity of hydrogen fuel, is crucial. Although Pd has comparable HOR activity to Pt, the exclusive use of Pd as anode catalysts of PEMFC has not been satisfactory for the replacement of Pt. We confirmed in our previous report (K. Kwon et al., Catal Today, 232 (2014) 175) that the insufficient HOR activity of Pd could be supplemented by coupling with other elements or compounds such as Ru and tungsten oxide. To investigate the effect of alloying with Ru thoroughly, the calculation of hydrogen binding energy was performed on the basis of spin polarized density functional theory. Pure Pd(001) and Ru(001), Pd monolayer on Ru, and Pd bilayer on Ru are considered as model systems in the calculation. Strain and ligand effects are only applicable to bimetallic models (Pd monolayer on Ru and Pd bilayer on Ru). The negative sign of strain and ligand effects stands for a decrease in binding energy for PdRu alloy. Meanwhile, instead of making an effort to turn the model alloy systems into nanoparticles of Pd mono/bilayer on Ru, which would not be realistic in a few nm dimension, the actual confirmation of HOR enhancement at the level of half cell and PEMFC single cell was obtained by fabricating homogeneous PdRu alloy nanoparticles on carbon support. PdRu nanoparticles of different Pd:Ru atomic ratios of 1:0, 9:1, 1:9, and 0:1 were characterized with TEM and XRD, and compared with a commercial state-of-the-art Pt-based anode catalyst (PtRu1.5/C) in electrochemical experiments. The PdRu9 catalyst shows the highest HOR activity among the PdRu samples, which is comparable to the PtRu catalyst, even though the respective Pd and Ru have lower activity than PtRu. The highest HOR activity of the Ru-richest PdRu nanoparticles could be in line with the highest HOR activity of the Ru-richest PdRu model system (Pd monolayer on Ru).

Pd-Ru core-shell nanoparticles with tunable shell thickness for active and stable oxygen evolution performance.

For Ru nanoparticles to be effective oxygen evolution reaction (OER) catalysts an approach is needed that stabilizes Ru while retaining high activity. Here, we present a synthesis for Pd-Ru core-shell nanoparticles with tunable shell thicknesses between 0.3-1.2 nm. The Pd core stabilizes the Ru shell to increase the stability by up to 10×, while maintaining the high current densities of pure Ru nanoparticles. Results show that the activity and stability of the nanoparticles is highly dependent on the nanoparticle shell thickness, with thin Ru shells and full coverage of the Pd core being vital for increasing both activity and stability.

Graphene-supported Pd–Ru nanoparticles with superior methanol electrooxidation activity

Pd–Ru bimetallic nanoparticles dispersed on graphene nanosheets (GNS) have been obtained by a microwave-assisted polyol reduction method and investigated for methanol electrooxidation in 1M KOH+1M CH3OH at 25°C. Structural and electrochemical characterizations of electrocatalysts are carried out by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, cyclic voltammetry, CO stripping voltammetry and chronoamperometry. The study shows that introduction of Ru (1–10 wt.%) into 40wt.%Pd/GNS produces an alloy of Pd and Ru with the face centered cubic crystal structure. The electrocatalytic activity increased with increasing percentage of Ru in the Pd–Ru alloy showing maximum with 5wt.%Ru. The electrocatalytic activity of the 40wt.%Pd–5wt.%Ru/GNS electrode at E=−0.10V vs. Hg/HgO was ∼2.6 times greater than that of the base (40wt.%Pd/GNS) electrode. Based on the methanol oxidation current, measured at 1h during the chronoamperometry tests at E=−0.10V vs. Hg/HgO, the active 40wt.%Pd–5wt.%Ru/GNS electrode exhibited ∼72% and ∼675% higher poisoning tolerance as compared to 40%Pd/GNS and 40%Pd/multiwalled carbon nanotube electrodes, respectively.

Nanostructured PdRu/C catalysts for formic acid oxidation

Pd and bimetallic PdRu nanoparticles supported on Vulcan XC-72 carbon prepared by the microwave-assisted polyol process are examined as electrocatalysts for the electrooxidation of formic acid. The catalysts are characterized by transmission electron microscopy and X-ray diffraction. The Pd and PdRu nanoparticles with sizes of <10 nm display the characteristic diffraction peaks of a Pd face-centered cubic (fcc) crystal structure. It is found that the addition of Ru to Pd/C can decrease the lattice parameter of Pd (fcc) crystal. The electrocatalytic activities of the catalysts are evaluated in sulfuric acid solution containing 1 M formic acid using linear sweeping voltammetry and chronoamperometry. The results show that Pd5Ru1/C displays the best electrocatalytic performance among all catalysts for formic acid electrooxidation.

Micelle-hosted bimetallic Pd–Ru nanoparticle for in situ catalytic hydrogenation in supercritical CO 2

Bimetallic Pd–Ru nanoparticles of different elemental ratios are prepared via in situ reduction of their simple salts in reverse micelles in supercritical carbon dioxide (scCO 2). The optimised Pd:Ru (1:1) nanoparticle shows the highest activity for hydrogenation of functionalised alkene under mild conditions, which can be easily recycled under the reaction conditions without use of organic solvent.