Pd Sn Research Articles

Electrochemical nitrate reduction over bimetallic Pd–Sn nanocatalysts with tunable selectivity toward benign nitrogen

Nitrate is recognized as a highly impactful water contaminant among various pollutants in water. To address the ever-growing demand for water purification, this work investigates the bimetallic palladium (Pd) and tin (Sn) catalysts, which are electrochemically deposited on stainless steel mesh support (Pd–Sn/SS) for the selective conversion of harmful nitrate (NO3−) into benign nitrogen (N2) gas. Results indicate that the bimetallic composition in Pd–Sn/SS electrodes substantially influenced the reaction route for nitrate reduction as well as the performance of nitrate transformation and nitrogen selectivity. It is found that the electrode prepared from Pd:Sn = 1:1 (mole ratio) demonstrates an outstanding nitrate conversion of 95%, nitrogen selectivity of 88%, and nitrogen yield of 82%, which outperform many reported values in the literature. The electrochemically synthesized bimetallic electrode proposed herein enables a new insight for promoting the reactivity and selectivity of nitrate reduction in water.

Enhancing the bioactivity and ductility of bulk metallic glass by introducing Fe to construct semi-degradable biomaterial

Porous Ti–Zr–Cu–Pd–Sn bulk metallic glass (BMG) produced by Spark Plasma Sintering (SPS) in our previous work demonstrates bone-like mechanical properties, effectively mitigating the issue of stress shielding within the implant. Nevertheless, concerns persist regarding the BMG's brittleness and its lack of bioactivity, both of which pose concealed risks in practical applications. In light of these challenges, a semi-degradable biomaterial, the MG-Fe composites, has been meticulously crafted via SPS in this work. The incorporation of ductile Fe phase in the MG matrix significantly enhances its plasticity. Moreover, the degradation of Fe results in the deposition of Ca–P compounds, imbuing the MG-Fe composites with a degree of bioactivity. Furthermore, by introducing a gradient porous structure, researchers have managed to fine-tune the mechanical properties of the MG-Fe composites. This innovative design imparts plastic and ductile compression deformation behavior to the gradient porous MG-Fe composites, offering a potential solution to the issue of brittle fracture behavior observed in conventional brittle BMGs. In addition, the introduction of the gradient porous structure serves to further accelerate the degradation rate of Fe. This advancement holds the potential to strike a dynamic balance with the growth rate of human bone, further elevating the bioactivity of the MG-Fe composites.

Selective Electrocatalysis of Nitrous Oxide Reduction Reaction to Nitrogen at Carbon-Supported Pt–Pd–Sn Nanoparticles

Nitrous oxide (N2O) is the third largest greenhouse gas and must be removed using a green method at ambient conditions such as electrocatalysis. Here, we report carbon-supported Pt–Pd–Sn nanoparticles (Pt–Pd–Sn/C)...

Effects of thermal cycling on the thermal and magnetic response of Ni–Mn–Sn–Pd alloys

AbstractMagnetic refrigeration is an option to replace conventional refrigeration. There are many studies that analyze materials with magnetocaloric effect during the first cooling-heating cycle, without analyzing the influence of cycling (necessary to check its applicability). In this work, we proceed to analyze the crystallographic structure (X-Ray diffraction) and the thermal (differential scanning calorimetry) and thermomagnetic (PPMS cycles and ZFC–FH–FC scans) response after a hundred thermal cycles of two Heusler alloys, Ni49Mn36Sn14Pd1 and Ni48Mn36Sn14Pd2 (at.%), that have been produced by melt spinning as ribbon flakes. In order to check its stability from cycling, these ferromagnetic alloys have been subjected to a hundred of thermal cycles (heating/cooling to provoke the austenite to martensite reversible transformation. The comparison before and after cycling behavior allow us to state that the reduction of the crystallographic defects favors higher atomic order. Likewise, the thermodynamic parameters (entropy and enthalpy) and the magnetic response have been reduced at about 10–12%.

A re-evaluation of stannopalladinite using modern analytical techniques

AbstractAn investigation of sample 41647 from the Platinum Placer of Ugol'nyi Ruchei, Norilsk Cu–Ni deposit, Russia, stored in the systematic collection of the Fersman Mineralogical Museum, revealed that it contained a mineral that can be identified as the original stannopalladinite described in 1947. As the literature information on the latter is controversial, the mineral was re-investigated using modern analytical techniques. Stannopalladinite occurs as spherical and ovoid-shaped grains up to 0.08 mm, closely intergrown with tetraferroplatinum as part of flattened, prismatic crystals up to 6 mm long. The micro-indentation hardness of stannopalladinite (VHN, 30 g load) is 244 kg/mm2 (range 233–266, n = 4), corresponding to a Mohs hardness of 4. The calculated density is 9.781 g/cm3. In reflected light, stannopalladinite is pale pink. The bireflectance is noticeable only in oil immersion. In crossed nicols the mineral exhibits strong anisotropy with colour effects changing from reddish purple to greyish blue and polysynthetic twinning of grains. The reflectance curves show distinct anomalous dispersion. The chemical composition (wt.%, electron microprobe data, mean of 11 analyses) is: Cu 8.48, Pd 61.21, Pt 0.89, Sn 25.87, Pb 3.70, total 100.15. The empirical formula calculated on the basis of 4 atoms per formula unit is (Pd2.42Cu0.56Pt0.02)Σ3.00(Sn0.92Pb0.08)Σ1.00. The ideal chemical formula of stannopalladinite is therefore proposed as (Pd,Cu)3Sn instead of Pd3Sn2 used in the official IMA List of Minerals. The strongest powder X-ray diffraction lines are [dobs, Å (I, %) (hkl) ]: 2.292 (42) (231), 2.166 (100) (331), 2.034 (10) (710), 1.916 (15) (141) and 1.851 (15) (630). The powder X-ray data are indexed in the orthorhombic unit cell with a = 14.634(2), b = 8.5253(6), c = 4.5946(3) Å and V = 573.24(7) Å3 (Z = 8). Stannopalladinite can be reliably identified among all other minerals belonging to the binary Pd–Sn and ternary Pd–Cu–Sn systems by a combination of chemical, optical and X-ray data.

CALPHAD Modelling of Ag–Pd–Sn Ternary System

CALPHAD modelling of the Ag–Pd–Sn ternary system has been performed. The disordered phases, the melt and the fcc phase were described using the substitutional solution model. Sublattice models were used to describe intermetallic compounds and the ternary phase. The two-sublattice model (Ag,Pd)4(Ag, Sn) used for the ternary phase made it possible to reproduce the inclination of its homogeneity range. The results of the thermodynamic calculation of the Ag–Pd–Sn system are in good agreement with the experimental data on phase equilibria and enthalpies of formation of the liquid. The agreement with the data on the partial Gibbs energy of tin in the liquid is somewhat worse.

CALPHAD Modelling of Ag–Pd–Sn Ternary System

CALPHAD Modelling of Ag–Pd–Sn Ternary System

Pd–Sn Alloy Catalysts for Direct Synthesis of Hydrogen Peroxide from H2 and O2 in a Microchannel Reactor

Direct synthesis of hydrogen peroxide (DSHP) from H2 and O2 offers a promising alternative to the present commercial anthraquinone method, but it still faces the challenges of low H2O2 productivity, low stability of catalysts, and high risk of explosion. Herein, by loading in a microchannel reactor, the as-synthesized Pd-Sn alloy materials exhibit high catalytic activity for H2O2 production, presenting a H2O2 productivity of 3124 g kgPd-1 h-1. The doped Sn atoms on the surface of Pd not only facilitate the release of H2O2 but also effectively slow down the deactivation of catalysts. Theoretical calculations demonstrate that the Pd-Sn alloy surface has the property of antihydrogen poisoning, showing higher activity and stability than pure Pd catalysts. The deactivation mechanism of the catalyst was elucidated, and the online reactivation method was developed. In addition, we show that the long-life Pd-Sn alloy catalyst can be achieved by supplying an intermittent flow of hydrogen gas. This work provides guidance on how to prepare high performance and stable Pd-Sn alloy catalysts for the continuous and direct synthesis of H2O2.

Mössbauer-spectroscopic characterization of the stannides Sr2Pd2Sn and Eu2Pd2Sn

Abstract The Ca2Pd2Ge-type stannides Sr2Pd2Sn and Eu2Pd2Sn were synthesized by reaction of the elements in sealed tantalum ampoules in a high-frequency furnace and characterized by powder X-ray diffraction. The structure of Sr2Pd2Sn (Fdd2, a = 1063.95(5), b = 1623.22(9), c = 594.63(14) pm, wR2 = 0.0472, 972 F 2 values and 26 variables) was refined from single-crystal X-ray diffractometer data. The striking structural motif features equidistant chains formed by the palladium atoms (304.7 pm Pd–Pd), which are interlinked by the tin atoms (266.9 and 268.7 pm Pd–Sn). Together, the palladium and tin atoms form a three-dimensional [Pd2Sn] δ– polyanionic network in which the strontium atoms reside in larger cavities. The divalent character of europium in Eu2Pd2Sn was manifested by 151Eu Mössbauer spectroscopy. The isomer shift is δ = −9.48(1) mm s−1 at room temperature. The results of 119Sn Mössbauer-spectroscopic experiments have confirmed the tin site determined by the single-crystal study, the isomer shifts being δ = 1.71(1) mm s−1 for Eu2Pd2Sn and δ = 1.73(1) mm s−1 for Sr2Pd2Sn. Sr2Pd2Sn is a Pauli paramagnet with a susceptibility of 2.2(1) × 10−5 emu mol−1 at room temperature. Eu2Pd2Sn shows Curie-Weiss paramagnetism with an experimental magnetic moment of 7.85(1) µB per Eu atom, confirming divalent europium. The europium magnetic moments order antiferromagnetically at T N = 14 K.

Experimental investigation of Ag–Pd–Sn ternary system

Isothermal sections of the Ag–Pd–Sn system at 500 and 800 °C were plotted based on the XRD and EDX results. The solubility of Sn in palladium and silver-based fcc solid solution has nearly zero minimum around the Ag corner. The Pd3Sn and γ-Pd2–xSn phases show significant dissolution of Ag and extend towards the Ag corner. The other Pd–Sn and Ag–Sn binary phases dissolve under 5 at.% of the third component. A new τ1 ternary phase was discovered in the Pd-rich region. Its XRD pattern corresponds formally to In structure type, but the actual arrangement of the atoms in the τ1 phase most probably corresponds to tetragonal Al3Ti type structure.

Synthesis and Design of Hybrid Metalloporphyrin Polymers Based on Palladium (II) and Copper (II) Cations and Axial Complexes of Pyridyl-Substituted Sn(IV)Porphyrins with Octopamine.

Supramolecular metalloporphyrin polymers formed by binding tetrapyrrolic macrocycle peripheral nitrogen atoms to Pd(II) cations and Sn(IV)porphyrins extra-ligands reaction centers to Cu(II) cations were obtained and identified. The structure and the formation mechanism of obtained hydrophobic Sn(IV)-porphyrin oligomers and polymers in solution were established, and their resistance to UV radiation and changes in solution temperature was studied. It was shown that the investigated polyporphyrin nanostructures are porous materials with predominance cylindrical mesopores. Density functional theory (DFT) was used to geometrically optimize the experimentally obtained supramolecular porphyrin polymers. The sizes of unit cells in porphyrin tubular structures were determined and coincided with the experimental data. The results obtained can be used to create highly porous materials for separation, storage, transportation, and controlled release of substrates of different nature, including highly volatile, explosive, and toxic gases.

Phase Equilibria of the In–Pd–Sn System at 500 °C and 800 °C: Experimental Study and CALPHAD Modeling

Phase equilibria in the In-Pd-Sn system were investigated by a combination of key experiments and thermodynamic modeling. Partial isothermal sections at 500 °C and 800 °C of the In-Pd-Sn system for Pd contents above 66 at.% have been plotted experimentally using scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDX) and X-ray diffraction (XRD). The solubility of the third component in binary compounds InPd3 and Pd3Sn was determined. The new ternary compound τ1 was found in Pd contents ranging from 20 to 25 at.% and at Sn contents varying from 5 to approximately 17 at.% Sn. This compound crystallizes in an Al3Ti-type tetragonal structure. Isostructural InPd2 and Pd2Sn phases from the In-Pd and Pd-Sn binary compositions form a continuous phase field in the ternary system at both temperatures. The temperatures of the solidus, liquidus, and phase transitions of the alloys along the Pd-In50Sn50 line were measured using DTA/DSC. Thermodynamic calculation of the In-Pd-Sn ternary system is performed using the CALPHAD method using the Thermo-Calc® software. The thermodynamic properties of the disordered fcc and liquid phases were described by the Redlich-Kister-Muggianu model. To describe intermetallic phases, namely, InPd3, Pd3Sn, τ1 and Pd2(InxSn1-x), a two-sublattice models was used. Thermodynamic description of the In-Pd-Sn system obtained in this study is in good agreement both with our results and the published experimental data.

Pd-Sn promoted NbOx/TiO2 catalysts for hydrogen photoproduction: Effect of Pd-Sn interaction on charge handling and reaction mechanism

Enhanced performance of Pd in the photocatalytic production of green hydrogen from methanol:water mixtures is achieved through the use of a sn-containing binary co-catalyst. For a Pd:Sn molar ratio of 1:1, the binary co-catalyst leads to an outstanding enhancement of activity under UV, visible and sunlight illumination, rendering a quantum efficiency value of 4 % in the latter case. A core–shell type interaction occurs between Pd metal nanoparticles and Sn oxo-hydroxyde nanoentities, resulting in an electronic modification of both components. The chemical effects of the binary co-catalyst were explored under reaction conditions using infrared spectroscopy. Overall, this study provides evidence that the electronic interaction between Pd and Sn promotes the adsorption and attack of the charge carrier species on the methanol molecule and controls the reaction mechanism, favoring the generation of hydrogen. This new system appears to be a strong candidate in the contribution to the new hydrogen economy through a green and eco-efficient process using renewable energy and reagents.

Thermodynamic Assessments of the Pd–Sn and Pt–Sn Systems With the Modified Quasi-chemical Model for Liquid

Thermodynamic Assessments of the Pd–Sn and Pt–Sn Systems With the Modified Quasi-chemical Model for Liquid

Activity and Stability of Pd Bimetallic Catalysts for Catalytic Nitrate Reduction

In this work, we study the effect of modifying the metal loading (0.5–1.5 wt.% Pd and 0.1–1 wt.% Sn or In), the impregnation order of noble or promoter metal (Pd–Sn or Sn–Pd), and the type of promoter metal (Sn or In) during the preparation process for a Pd bimetallic catalyst, supported on γ-alumina, used in the catalytic reduction of nitrate. The deposition of the noble metal over the promoter metal, especially with Pd:Sn ratios (wt.) of 1:10 and 1:2, favored the hydrogen spillover rate and increased the H concentration on the catalyst surface, enhancing NH4+ production. On the other hand, Pd–In catalysts showed higher activity than the Sn catalysts, as well as higher NH4+ selectivity. The stability of the Pd–Sn/Al2O3 (1.5–1 wt.%) catalyst was evaluated in long-term experiments for the treatment of synthetic water (100 mg L−1 NO3−) and three different commercial drinking waters. This Pd–Sn/Al2O3 catalyst achieved a stable nitrate conversion for a duration of 50 h in the synthetic water treatment. However, the catalyst showed a significant activity loss in the presence of other ions (different to NO3−) in the reaction medium, increasing slightly the selectivity to NH4+.

Catalytic hydrogenation of stearic acid to 1-octadecanol using supported bimetallic Pd–Sn(3.0)/γ–Al2O3 catalyst

Supported bimetallic palladium-tin catalyst on gamma-alumina (γ-Al2O3) (denoted as Pd–Sn(3.0)/γ-Al2O3; Pd = 5%wt and Pd/Sn molar ratio is 3.0) has been synthesized via the hydrothermal method at a temperature of 423 K for 24 h and reduced with H2 at 673 K for 3 h. The XRD patterns of the samples showed typical diffraction peaks of support γ-Al2O3, metallic Pd, Sn, and Pd–Sn alloy phases. Diffraction peaks of metallic Pd were observed at 2θ = 39.8°; 46.6°; and 68.0°, which can be attributed to the Pd(111), Pd(200), and Pd(220), respectively, while the diffraction peaks at 2θ = 39.8° and 41.0° can be attributed to Pd2Sn and Pd3Sn2, respectively, which may overlap with the Pd(111) species. The ammonia desorption and pyridine adsorption profiles showed Lewis and Brönsted acid sites. The specific surface area (SBET) of Pd–Sn(3.0)/γ-Al2O3 catalyst was 117.83 m2/g which is dominated by a micropore structure. The highest conversion of stearic acid was 99.1% with a yield of 1-octadecanol 43.2% was obtained at temperature 513 K, initial H2 pressure of 2.0 MPa, a reaction time of 13 h, and in 2-propanol/water (4.0:1.0 v/v) solvent.

Experimental Investigation and Thermodynamic Calculation of Ag–Pd–Sn Ternary System

Experimental Investigation and Thermodynamic Calculation of Ag–Pd–Sn Ternary System

Electroreduction of carbon dioxide to formate using highly efficient bimetallic Sn–Pd aerogels

Electrochemical reduction of carbon dioxide (CO2) to valuable materials is a promising approach to suppress atmospheric CO2 levels.

Crystal Structure and Magnetism of Noncentrosymmetric Eu2Pd2Sn.

The new intermetallic compound Eu2Pd2Sn has been investigated. A single crystal was selected from the alloy and was analyzed by single-crystal X-ray diffraction, revealing that this compound possesses the noncentrosymmetric Ca2Pd2Ge structure type being, so far, the only rare-earth-based representative. Bonding analysis, performed on the basis of DOS and (I)COHP, reveals the presence of strong covalent Sn–Pd bonds in addition to linear and equidistant Pd–Pd chains. The incomplete ionization of Eu leads to its participation in weaker covalent interactions. The magnetic effective moment, extracted from the magnetic susceptibility χ(T) is μeff = 7.87 μB, close to the free ion Eu2+ value (μeff = 7.94 μB). The maximum of χ(T) at TN ∼ 13 K indicates an antiferromagnetic behavior below this temperature. A coincident sharp anomaly in the specific heat CP(T) emerges from a broad anomaly centered at around 10 K. From the reduced jump in the heat capacity at TN a scenario of a transition to an incommensurate antiferromagnetic phase below TN followed by a commensurate configuration below 10 K is suggested.

Porous Ti-based bulk metallic glass orthopedic biomaterial with high strength and low Young's modulus produced by one step SPS

Abstract To alleviate the “stress shielding” of metallic biomaterials used as artificial bone, the state of art Ti45Zr10Cu31Pd10Sn4 porous bulk metallic glass (BMG) with adequate compressive strength of 180 MPa and Young's modulus of 27.2 GPa similar to nature bone was produced by a novel partial densification method using spark plasma sintering (SPS). The thermal mechanistic (sintering temperature, sintering rate and holding time) during SPS contributions to the densification behavior and the structures and mechanical properties of porous BMG were systematically explored under low loading pressure condition to obtain the optimal sintering process. With the help of this work, the potential application value of Ti–Zr–Cu–Pd–Sn BMG as substitute of human bone will be further enhanced.