Pd Ru Alloy Research Articles

Sub‐nano cluster decoration for the manipulation of the photogenerated carrier behavior of MoS2

AbstractFor most applications based on the photoelectric effect, uncontrollable photogenerated carrier behavior, such as trapping and recombination, is a common issue that reduces the carrier utilization efficiency. Herein, a sub‐nano cluster (Pd, Ru, and PdRu alloy) decoration strategy is proposed to manipulate the photogenerated carrier behavior in MoS2 to optimize the optoelectronic properties. After decoration, electrons can flow into sub‐nano cluster through PdS bonds and then return to MoS2 through RuS bonds at the sub‐nano cluster/MoS2 interface when holes are left in the channel for collection to achieve efficient carrier separation. In addition, the formation of metalS bonds also leads to the generation of mid‐gap states, which enables light absorption over a wide wavelength range. Therefore, the photodetector based on PdRu/MoS2 shows broadband photodetection ability from 532 to 1550 nm with high responsivity/external quantum efficiency of 310.8 A W−1/7 × 104% (532 nm), 4.2 A W−1/527% (980 nm), and 7.14 mA W−1/0.5% (1550 nm), as well as a fast response speed (rise/decay time of 11.5/12.0 ms). Our work offers new insight into manipulating the photogenerated carrier behavior to optimize the performance of semiconducting 2D materials for practical optoelectronic applications.image

Thermal Stability and CO Oxidation Property of Non-Equilibrium Pd–Ru Alloy Catalyst

Thermal Stability and CO Oxidation Property of Non-Equilibrium Pd–Ru Alloy Catalyst

Steam Conversion of Ethane and Methane–Ethane Mixtures in a Membrane Reactor with a Foil Made of a Pd–Ru Alloy

Steam Conversion of Ethane and Methane–Ethane Mixtures in a Membrane Reactor with a Foil Made of a Pd–Ru Alloy

One-step synthesis of non-equilibrium Pd-Ru alloys from Al-Pd-Ru quasicrystals and approximants

Non-equilibrium Pd–Ru alloys were synthesized by leaching quasicrystal (icosahedral quasicrystal, IQC: Al71Pd19Ru10) and approximants (3/2 approximant, P40: Al72Pd16.4Ru11.6, 1/1 approximant, C1: Al70.4Pd14.7Ru14.9) of Al–Pd–Ru alloys with 20 wt% NaOH aqueous solution. The Pd-Ru alloys were investigated using XRD and HAADF-STEM, which showed that Pd and Ru were mixed and formed a non-equilibrium state (atomic ratio: 0.9 < Pd/Ru < 2). The Pd–Ru alloy obtained by leaching of P40 phase was found to exhibit high catalytic performance toward CO oxidation than Pd and Ru catalysts obtained by leaching of Al3Pd (decagonal quasicrystal) and Al13Ru4 (decagonal approximant), respectively (i.e., the alloying effect). Consequently, Al-Pd-Ru quasicrystals and approximant alloys are found to be useful precursors to obtain the non-equilibrium Pd-Ru alloys.

Steam Conversion of Ethane and Methane–Ethane Mixtures in Membrane Reactor with a Foil from Pd–Ru Alloy

The features of steam conversion of ethane and methane-ethane mixtures containing 5, 10 and 15% ethane in a membrane reactor with a 30 μm thick Pd–Ru foil at temperatures of 1800 and 3600 h–1 and steam/feed rations of 3 and 5 have been investigated. Comparative experiments with “non-membrane” reaction have shown that in the membrane reactor the feedstock conversion to form H2 and CO2 increases and ethane hydrocracking decreases. Increasing the rate of H2 recovery through the membrane by permeate evacuation leads to an increase in the yield of H2 and CO2. With a decrease in the steam/feed ratio from 5 to 3, the ethane hydrocracking and the rate of carbon deposits formation increases. Optimal conditions for steam conversion of ethane and methane-ethane mixtures are T = 773 K, feed space velocity of 1800 h–1 and steam/feed ratio of 5. The established regularities are similar to those obtained earlier for other types of raw materials (mixtures of methane with propane, propane, n-butane, a mixture simulating the average composition of associated petroleum gas) in this membrane reactor.

Concurrent alloying and vacancy engineering for intensifying hydrogen spillover towards alcohol–water co-electrolysis

A PdRu–RuO2heterostructure with a well-defined PdRu alloy and oxygen-vacancy-enriched RuO2is constructed to intensify the hydrogen spillover from Ru to RuO2.

Highly selective gas sensor for rapid detection of triethylamine using PdRu alloy nanoparticles functionalized SnO2

Triethylamine is a kind of volatile organic compound, which is flammable and toxic. Here, PdRu alloy nanoparticles (NPs) were used for modifying SnO2 to make it more selective for triethylamine. Monodisperse PdRu alloy NPs were produced through coreduction in polyol solution, while the SnO2 nanoparticles with a small particle size were generated by a hydrothermal method. The sensor based on 0.5 wt% PdRu-SnO2 exhibited a high response (S = 256) to 100 ppm triethylamine when the temperature was 220 °C. The response was 12 times more than trimethylamine and 10 times higher than that to NH3. Moreover, it showed rapid response speed (2 s) to triethylamine. SnO2 with small particle size had many acid sites, which showed selective detection of triethylamine due to acid-base reaction. Besides, the catalytic property of PdRu NPs also played a role in improving performance. This work provides a new method for the fast identification of triethylamine in chemical industry plant.

Thermodynamic stability of Pd-Ru alloy nanoparticles: combination of density functional theory calculations, supervised learning, and Wang-Landau sampling.

Solid-solution alloy nanoparticles (NPs) comprising Pd and Ru, which are immiscible in the bulk state, have been synthesised and show excellent catalytic performance. To date, most studies have evaluated the stability of alloy NPs at 0 K only. Because the thermodynamic stability of Pd-Ru alloy NPs may differ from that of the alloy in the bulk state, the stable configuration of the NPs must be evaluated under a finite temperature. Such stability evaluations are critical for developing the durable NPs as catalysts. Therefore, the thermodynamic stability of Pd-Ru alloy NPs was analysed using density functional theory (DFT), supervised learning (SL), and Wang-Landau sampling. We calculated the excess energy of Pd-Ru alloy NPs, which depends on their composition, structure, NP size, adatom type, and defects, and applied SL to all models. The excess energies of the Pd-Ru alloy NPs expressed by structural information, such as the surface-to-volume ratio, correlated with those calculated using DFT. Wang-Landau sampling based on the energy estimated by SL gave the thermodynamic stability of Pd-Ru alloy NPs with a stable configuration under a finite temperature. The solid-solution atomic configuration was subdivided into partially mixed configurations in the surface layer or in the core of the NPs, which is different from the bulk state. The partially mixed configuration was determined by the overall composition and surface properties. The findings from the combined method could contribute to a better understanding of the alloy-NP stability and their application in catalysis.

Cold plasma enhanced preparation of high performance PdRu/C formic acid dehydrogenation catalysts

A facile and environment-friendly atmospheric-pressure cold plasma treatment method was adopted to synthesize activated carbon supported bimetallic PdRu catalysts (PdRu/C–P) toward formic acid (FA) dehydrogenation. The results showed that the PdRu/C–P with a Pd/Ru mass ratio of 9/1 exhibited the highest activity featuring total gas volume of 337.2 ml during 4 h and initial turnover frequency (TOF) value of 954.2 h−1. In comparison with the PdRu/C-T catalyst prepared by thermal reduction, enhanced FA dehydrogenation activity of the PdRu/C–P catalysts could be mainly attributed to the efficient electron transfer from Ru to active Pd in the PdRu alloy, and the high PdRu/C atomic ratios arising from the migration of the PdRu active species from the pores to the outer surface of the support affected by Coulomb repulsion effect in the plasma. The total gas volume generated by FA over the PdRu/C–P was decreased to 88.4% and 86.5% after the second and third reaction cycles, respectively, in comparison with the first cycle. However, they have been decreased to 64.6% and 64.4%, respectively, for PdRu/C-T prepared by thermal reduction. In addition, the performance of the PdRu/C–P is a little inferior to PdAu/C–P prepared by cold plasma, but its catalytic stability is much better than the expensive PdAu/C–P. The enhancement of catalytic stability for the PdRu/C–P catalyst is attributed to the small and stable particle size of PdRu, and less leaching of active species resulting from the strong metal-support interaction induced by cold plasma.

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/CNTs synthesized by microwave‐assisted method for high stable acidic oxygen evolution reaction

AbstractIt is the most efficient way to solve the sluggish kinetics of anodic oxygen evolution reaction during water electrolysis and realize rapid high‐purity hydrogen production by designing high performance oxygen evolution reaction (OER) catalysts. Herein, we have designed a series of PdRu nanoparticles‐modified carbon nanotubes (PdRu/CNTs) by rapid solvent‐free microwave‐assisted method. In this process, CNTs were chosen as the substrate because of its highly stable structure and fast electron transfer. What's more, Pd and Ru have formed a PdRu alloy and occurred partial oxidation based on the analysis of X‐ray diffraction and X‐ray photoelectron spectra spectrums. Through the regulation of composition, Pd69Ru31/CNTs exhibit excellent OER performance in 0.1 M HClO4 with a lowest overpotential of 225 mV at the current density of 10 mA cm−2. In the meanwhile, the current density of Pd69Ru31/CNTs was almost unchanged after 10 h i‐t test, and the overpotential only occurred to 10 mV positive shift after 5000 testing cycles. This work provides a feasible way to design high performance Pd‐based OER catalysts.

Steam Reforming of n-Butane in Membrane Reactor with Industrial Nickel Catalyst and Foil Made of Pd-Ru Alloy

Steam Reforming of n-Butane in Membrane Reactor with Industrial Nickel Catalyst and Foil Made of Pd-Ru Alloy

Crystalline to amorphous transformation in solid-solution alloy nanoparticles induced by boron doping.

We synthesized a palladium-ruthenium-boron (Pd-Ru-B) solid-solution ternary alloy. Elemental mappings confirmed successful alloying of B with Pd-Ru body without changing the particle sizes, demonstrating the first discovery of this ternary alloy. Pair distribution function analysis revealed a drastic decrease in atomic correlation in Pd-Ru nanoparticles by B doping. This result gives the first example of structural transformation from crystalline to amorphous in solid-solution alloy nanoparticles induced by the doping of light elements.

Chemoselective hydrogenation of heteroarenes and arenes by Pd-Ru-PVP under mild conditions.

Monometallic (Pd, Ru or Rh) and bimetallic (Pd0.5–Ru0.5) alloy NPs catalysts were examined for the hydrogenation of quinoline. Pd–Ru alloy catalyst showed superior catalytic activity to the traditional Rh catalyst. The characterization of Pd0.5–Ru0.5 catalysts, HAADF-EDX mapping and XPS analysis suggested that the alloy state of PdRu catalysts remained unchanged in the recovered catalyst. Furthermore, the catalyst was highly selective for the hydrogenation of different arenes.

Pure hydrogen production by steam reforming of methane mixtures with various propane contents in a membrane reactor with the industrial nickel catalyst and a Pd–Ru alloy foil

Steam reforming of СН4 mixtures containing 5, 10, and 15% С3Н8 was studied in a membrane reactor with the industrial nickel catalyst and a membrane as a foil 30 μm thick of a Pd–Ru alloy. The reaction was studied at temperatures of 773 and 823 K and the mixture gas hourly space velocities equal to 1800 and 3600 h−1. Experiments were carried out under atmospheric pressure, and both sweep gas (N2) and vacuum conditions in the permeate side were used for Н2 recovery from the reaction mixture. The complete conversion of С3Н8 was observed under all conditions. It is shown for the first time that the main factor determining the influence of propane on the reaction parameters is the rate of Н2 recovery from the reaction mixture. A negative influence of С3Н8 on methane reforming was observed only in experiments using the sweep gas. This fact was proposed to be related to the insufficient СО conversion in the water-gas shift reaction. For vacuum conditions in the permeate side of the membrane reactor, the rate of Н2 recovery from the reaction mixture increases, which increases the CO conversion in the water-gas shift reaction. In this case, the negative effect of С3Н8 on methane reforming is minimum and is almost absent at 823 K. The conversion of methane is 93–97%, depending on the flow rate of the raw materials, and 75–80% Н2 are recovered from the reaction mixture.

Steam Reforming of Methane and Its Mixtures with Propane in a Membrane Reactor with Industrial Nickel Catalyst and Palladium–Ruthenium Foil

Steam reforming of methane and its mixtures containing 5 and 10% propane has been studied in a membrane reactor with an industrial nickel catalyst NIAP-03-01 and a membrane in the form of 30-μm foil made of a Pd–Ru alloy. At T = 823 K and a feed space velocity of 1800 h−1, the almost complete methane conversion is achieved, the selectivity for CO2 is more than 50%, and about 80% H2 is recovered from the reaction mixture. High conversion of CH4 in the membrane reactor under mild conditions allows the steam reforming of its mixtures with C2+ alkanes to be conducted in a single process, as shown by the example of model mixtures containing C3H8. Under selected conditions (T = 773 or 823 K, a feed space velocity of 1800 or 3600 h−1, a steam/methane ratio of 3 or 5, atmospheric pressure), almost complete C3H8 conversion is observed. The main “undesirable” reaction is methanation, leading to a decrease in the CH4 conversion. In the system under study, CH4 is formed with an increase in the feed space velocity. Methanation occurs as a result of C3H8 hydrocracking at a steam/feedstock ratio = 3 or the hydrogenation of CO2 as this ratio is increased to 5. The optimal conditions for steam reforming of methane mixtures containing up to 10% C3H8 are T = 823 K, steam/feedstock ratio = 5, and the feed space velocity of 1800 h−1. Under these conditions involving evacuation of the permeate, the feedstock conversion is complete, the selectivity for CO2 is 50%, and more than 70% H2 is recovered from the reaction mixture.

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.

Synthesis and characterization of bimetallic catalysts Pd-Ru and Pt-Ru supported on γ-alumina and zeolite FAU for the catalytic transformation of HMF

It is well known the effects and limitations of the use of fossil fuels, for that reason is necessary to establish alternative sources of energy. The 5-hydroxymethylfurfural (HMF) is a chemical compound that can be obtained from the carbohydrates present in the biomass. Is a key compound for the obtaining of several valuable chemicals, many of them have a promising application as biofuels. In the present work, Pd-Ru and Pt-Ru bimetallic catalysts with low metal content (0.5%) supported on commercial γ-Al2O3 and FAU zeolite prepared by hydrothermal method, were synthesized and characterized to transform HMF into valuable chemicals under mild reaction conditions. Two crystallographic phases were found to coexist in the zeolite synthesized as support, the FAU phase prevailing over the LTA when calcined at 550 °C. The system studied with formic acid as hydrogen donor, under mild reaction conditions, showed a partial hydrogenation of HMF molecule evidenced in the 5-MF and 2,5-DMF formation. Also, a partial oxidation and esterification is happening for the formation of 2,5-DFF and 5-A-2-F, respectively. The catalysts supported on FAU showed better conversion of HMF that catalysts supported on γ-Al2O3. Although all metals showed catalytic activity by separed, Pd-Ru combination was more selective to produce 5-MF, 2,5-DMF and 2,5-DFF than Pt-Ru combination, and showed production of valuable furan derivatives even in their second and thir use. Pd–Ru/FAU catalyst formed a PdRu alloy phase, which can be related to its better catalytic performance.

Combined theoretical and experimental studies of CO oxidation on PdRu nanoalloys

The oxidation of carbon monoxide (CO) over PdRu solid solution nanoparticles was studied by the combined theoretical and experimental approaches. In this work, CO and O adsorptions on PdRu alloy surface models were theoretically investigated to understand the kinetics of CO oxidation reaction. It was found that CO adsorption on Pd atom in the PdRu alloy surfaces is weaker than on monometallic surfaces. From the experiment, reaction order of CO on the PdRu surface was observed to be smaller than that on Pd surface. While, the positive first order with respect to O2 obtained for both Pd and PdRu alloy surfaces. Catalytic reaction mechanism is discussed on the basis of both theoretical and experimental observations.