Palladium Content Research Articles

Eco-friendly rapid removal of palladium from aqueous solutions using alginate-diatomite magnano composite

The aim of this study was to evaluate the feasibility of magnetic polymer imprinted diatomite composite (MPIDC) to remove of palladium from aqueous solutions. The chemical co-precipitation method was used to synthesis of MPIDC. The obtained results from study of the MPIDC adsorbent characterization, indicated the presence of sodium alginate, diatomite and Fe3O4 in the MPIDC structure.The BJH desorption cumulative pore volume, the average pore size of the sample and the BET specific surface area were 1.343 cm3g−1, 24.605 nm and 63.44 m2g−1, respectively. Modeling studies were done using R software based on response surface methodology (RSM). The ANOVA analysis was used in order to determine the best-fit model. Based on the results obtained from ANOVA analysis, the second-order model (SO), indicated a satisfactory adjustment with experimental data. The solver method was applied for optimization study. Based on the results obtained from solver method, the maximum adsorption performance of 90.04% (involving all parameters simultaneously) was achieved at pH of 5.45; initial palladium concentration of 15.13 mg L−1; contact time of 104.8 min and MPIDC dosage of 0.98 g L−1. The statistical terms including coefficient of determination (R2), root mean square error (RMSE), chi-square statistic (X2), average percentage error (APE) and residual sum of squares (RSS) were used in order to determine the best-fit isotherm and kinetic models. Investigation of statistical results revealed the good agreement of experimental data with three- parameter nonlinear Sips model. Therefore, adsorption of palladium onto MPIDC, at high concentration is related to Langmuir model, whereas the adsorption process at the low concentrations of palladium implies from Freundlich model. Based on the Sips model, maximum adsorption capacity of MPIDC was calculated 60.2 mg g−1. With comparison of the nonlinear kinetic models, pseudo-second-order was found to agree well with the experimental data. It reveals adsorption of palladium molecules onto sorption sites on the adsorbent surface is based on a chemical adsorption.The thermodynamic data revealed the exothermic nature and spontaneous sorption for the adsorption of palladium onto MPIDC.

Dilute Pd-in-Au alloy RCT-SiO2 catalysts for enhanced oxidative methanol coupling

Dilute alloy catalysts have the potential to enhance selectivity and activity for large-scale reactions. Highly dilute Pd-in-Au nanoparticle alloys partially embedded in porous silica (“raspberry colloid templated” (RCT)-SiO2) prove to be robust and selective catalysts for oxidative coupling of methanol. Palladium concentrations in the bimetallic nanoparticles as low as ~3.4 at.% catalyze the production of methyl formate with a selectivity of ~95% at conversions of ~55%, whereas conversions are low (<10%) for ~1.7 at.% Pd-in-Au nanoparticle and pure Au nanoparticle catalysts. Fractional reaction orders for both CH3OH and O2 measured for ~3.4 at.% Pd-in-Au nanoparticles supported on RCT-SiO2 indicated a complex mechanism in which the sites for O2 dissociation are not saturated. Optimal methyl formate production was found for an equimolar mixture. There is no conversion of methanol in the absence of O2 between 360 and 450 K. All observations are consistent with a mechanism derived from model studies, requiring that clusters of Pd be available on the catalyst for O2 dissociation.

Determination of elemental impurities of Arsenic, Cadmium, Mercury, Lead and Palladium content in Testosterone propionate by using ICP-MS

The aim of the present work is to develop and establish a validated analytical method for the determination of arsenic, cadmium, mercury, lead and palladium content in testosterone propionate by using inductive coupled plasma mass spectroscopy (ICP-MS). Samples were analyzed after a preparation of sample solution by dissolving in suitable solvents of concentrated nitric acid and concentrated hydrochloric acid. In the present method, RF power of 1550 watts, RF matching is 1.80 V, nebulizer flow of 0.10 rps and plasma view at spectrum mode were used. Octopole conditions are He flow is on, He flow rate is 4.3 mL/min and energy discrimination is 3.0 V were used. Significant savings in sample volumes, reagents, analysis cost and time are realized. Arsenic, cadmium, mercury, lead and palladium are primary concerned due to their high toxicity and potential contaminants should be limited in testosterone propionate and the developed method was validated according to ICH and USP guidelines. The correlation coefficient, recovery rate, LOD and LOQ reached the acceptable limits. The validated method was selective, sensitive, rapid and capable of the determination of elemental impurities of arsenic, cadmium, mercury, lead and palladium content in bulk drugs.

Facile Synthesis and Characterization of Palladium@Carbon Catalyst for the Suzuki-Miyaura and Mizoroki-Heck Coupling Reactions

Palladium-based carbon catalysts (Pd/C) can be potentially applied as an efficient catalyst for Suzuki–Miyaura and Mizoroki–Heck coupling reactions. Herein, a variety of catalysts of palladium on activated carbon were prepared by varying the content of ‘Pd’ via an in situ reduction method, using hydrogen as a reducing agent. The as-prepared catalysts (0.5 wt % Pd/C, 1 wt % Pd/C, 2 wt % Pd/C and 3 wt % Pd/C) were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and Brunauer–Emmett–Teller (BET) analyses. The catalysts were tested as a coupling catalyst for Suzuki–Miyaura coupling reactions involving aryl halides and phenyl boronic acid. The optimization of the catalyst by varying the palladium content on the activated carbon yielded Pd/C catalysts with very high catalytic activity for Suzuki reactions of aryl halides and a Mizoroki–Heck cross-coupling reaction of 4-bromoanisol and acrylic acid in an aqueous medium. A high ‘Pd’ content and uniform ‘Pd’ impregnation significantly affected the activity of the catalysts. The catalytic activity of 3% Pd/C was found to make it a more efficient catalyst when compared with the other synthesized Pd/C catalysts. Furthermore, the catalyst reusability was also tested for Suzuki reactions by repeatedly performing the same reaction using the recovered catalyst. The 3% Pd/C catalyst displayed better reusability even after several reactions.

Carbon black modified with silver and low concentration of palladium as effective catalysts for electroreduction of oxygen in alkaline solutions

Carbon black modified with silver and low concentration of palladium as effective catalysts for electroreduction of oxygen in alkaline solutions

Multifunctional Pd-Based Nanocomposites with Designed Structure from In Situ Growth of Pd Nanoparticles and Polyether Block Amide Copolymer.

Nanocomposites containing palladium nanoparticles were synthesized by in situ generation route from palladium acetate and a polyether block amide matrix with the aim to obtain materials with specific nanoparticle location and function properties. The chosen Pebax matrix was composed of a continuous soft phase containing dispersed semi-crystalline rigid domains. Nanocomposite films with Pd amount up to 30 wt% (corresponding to 3.5 vol%) were directly prepared from the palladium precursor and the copolymer matrix through a solvent cast process. The microstructure of the films was investigated by microcalorimetry, X-ray diffraction analyses and transmission electron microscopy. The nanocomposites’ function properties in terms of electrical conductivity and interaction towards hydrogen were studied as a function of the palladium content. It was shown that the spherical crystalline Pd nanoparticles that were in situ formed were located in the continuous soft phase of the copolymer matrix. They did not induce modification of Pebax microstructure and chain mobility. The specific location of the metal nanoparticles within the copolymer matrix associated with their low size allowed obtaining conductive materials for Pd amount equal to 3.5 vol%. Moreover, the affinity towards hydrogen evidenced from hydrogen permeation experiments made this nanocomposite series promising for further development in sensing applications.

Electrospinning Encapsulation of Pd Nanoparticles into α-Fe2O3 Nanofibers Windows Enhanced Acetone Sensing

Different concentrations (0, 1 mol%, 2 mol%, 6 mol% and 8 mol%) of palladium (Pd) nanoparticles modified hematite nanofibers (Pd NPs@ α-Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> NFs) were successfully synthesized via a facile electrospinning method followed by the calcination treatment. Their surface morphologies, crystal structures and chemical compositions were subsequently characterized in order to find optimum modification percentage. The gas sensing experiments on Pd NPs@ α-Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> -based gas sensors revealed that encapsulation of Pd NPs into α-Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> NFs could significantly improve their sensing performances. Specifically, the as-prepared Pd <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> /Fe gas sensor exhibited higher response ( R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">air</sub> /R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">gas</sub> = 16.6) toward 100 ppm acetone at 220°C, which was 3.4 times higher than that of Pd <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> /Fe sensor (4.89). Meanwhile, the Pd <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> /Fe sensor also showed shorter response/recovery (4 s/4 s), low limit of detection (LOD) (50 ppb) and good selectivity and long-term stability. The enhanced gas sensing properties of Pd NPs@ α-Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> -based gas sensors could be attributed to the chemical and electronic sensitization of Pd NPs.

Microstructure of Aluminide Coatings Modified by Pt, Pd, Zr and Hf Formed in Low-Activity CVD Process

In the present article the doping of aluminide coatings by Pt/Pd as well as Hf or Pd using industrial processes was developed. The different combinations of doping elements were tested as well as their influence on chemical composition of coatings was initially investigated. The Pt and Pd and both Pt + Pd was electroplated on the surface of the MAR M247 nickel superalloy. The Zr or Hf was doped during low activity CVD aluminizing process using industrial Bernex BPX Pro 325S system. The conducted research showed that Pt and Pd formed the (Ni, Pd, Pt) Al solid solution in the outer additive layer. The higher concentration of palladium in the near surface and in the whole additive layer was detected. The platinum was presented below the surface of aluminide coating. The Zr or Hf was detected mainly in the diffusion zone. The low concentration of Zr (about 0.1 wt.%) in the outer zone was observed. The hafnium was detected mainly in the diffusion zone but in the outer additive layer a small concentration of this element was measured. The obtained results showed that formation of three elements (Pd, Pt) + Zr or Hf modified aluminide coating using proposed technology is possible. The structure of all obtained aluminide coatings was typical for a low-activity, high temperature (LAHT) formation process mainly by outward diffusion of Ni from base material.

CO2‐to‐HCOOH Electrochemical Conversion on Nanostructured CuxPd100−x/Carbon Catalysts

AbstractSelective electrochemical conversion of CO2 to HCOOH is obtained at the surface of a carbon‐supported bimetallic cathode material composed of copper and palladium nanoparticles. Polycrystalline copper or large copper particles are well‐known to catalyze CO2 reduction to hydrocarbons at relatively negative potentials, or when their surface is covered by copper oxides (Cu2O and CuO). Cu‐based materials modified by various palladium contents (0&lt;×&lt;100), were synthesized by using the microwave‐assisted polyol method to serve as a cathode in the selective CO2‐into‐HCOOH transformation. Herein, we developed a targeted preparation route toward the metal content/catalytic activity relationship correlating atomic ratio with faradaic efficiency (FE) to formate formation (ca. 60 % FE) at −0.72 V vs. RHE, which represents a 703 mV overpotential at pH=7. Consequently, the occurrence of this reduction reaction slows down the parallel H2 production from the solvent consumption, while the neighboring Cu−Pd provides excellent activity and a good efficiency toward CO2 reduction via the hydridation of the CO2 molecule to orientate the reaction to formate rather than carbon monoxide or H2 evolution.

Injection and Extraction of Atomic Hydrogen on Cu–Pd- and Ag–Pd-Alloys in Alkaline Medium

The behavior of alloys of the Cu–Pd- and Ag–Pd-systems in the hydrogen evolution reaction in 0.1 M KOH aqueous solution is investigated. The role of copper and silver in the processes of the atomic hydrogen insertion and ionization is revealed. The mechanism of the hydrogen evolution reaction in aqueous alkaline solution on Cu,Pd- and Ag,Pd-alloys with the electronegative component content up to 60 at % is proposed. The limiting stage of the hydrogen evolution reaction on the palladium alloys in 0.1 M KOH is shown to be the atomic hydrogen ionization complicated by its diffusion in the solid phase. The parameters of hydrogen permeability for the systems under study are calculated. The maximum hydrogen permeability is achieved on the Ag80Pd alloy. Accordingly, alloys with higher palladium content, along with pure palladium, can be successfully used as effective materials for the atomic hydrogen purification and storage.

Perspectives for usage of adsorption semiconductor sensors based on Pd/SnO2 in environmental monitoring of carbon monoxide and methane emission

Nanosized semiconductor sensor materials based on SnO2 with different palladium contents were obtained via zol-gel technology with the use of ethylene glycol and hydrate of tin (VI) chloride as precursors. Morphology and phase composition of nanosized sensor materials were studied by X-ray diffraction and TEM methods. Catalytic activities of the Pd/SnO2 nanomaterials in the reaction of H2 and CO oxidation were investigated. Adsorption semiconductor sensors based on Pd/SnO2 nanomaterials were made by their calcination up to 620 0C in air and the sensors were found to be highly sensitive to presence of CO and CH4 in air ambient. Higher responses to CO of Pd-containing sensors in comparison with their responses to CH4 were confirmed by higher reaction activity of CO in catalytic oxidation reaction. Differences in sensitive properties of the sensors to methane and carbon monoxide were explained by features of the catalytic reactions of methane and carbon monoxide oxidation occurring on surfaces of the gas sensitive layers of the sensors.

Synthesis and Properties of a Carbon Monoxide Oxidation Catalyst Based on Plasma-Chemical Titanium Carbonitride, Titanium Dioxide, and Palladium

A CO oxidation catalyst based on plasma-chemical titanium carbonitride TiC0.2N0.8 and TiO2 with a palladium content of 10 wt % has been synthesized. The dependence of the reaction rate of CO oxidation at room temperature and low CO concentrations (<100 mg/m3) on the TiC0.2N0.8 content has been studied. It has been found that, at TiC0.2N0.8 concentrations from 8 to 10 wt %, the catalyst exhibited a maximum rate of the CO oxidation reaction, which was 2.5 times higher than the rate of reaction on a catalyst based on pure TiO2 that included palladium clusters. The catalysts are promising for use in catalytic and photocatalytic systems for air purification.

Electronic Effects on the Depropargylation Process in the Reaction‐based Fluorescent Detection of Palladium Species: Benzocoumarin‐based Ratiometric Sensing Systems

The palladium catalyzed cross‐coupling reactions are indispensable in organic synthesis of pharmaceutical compounds, demanding convenient tools for the analysis of residual palladium contents. Propargyl aryl ether‐type fluorescent sensing systems that detect Pd(0)/Pd(II)/Pd(IV) species through depropargylation require no additives. We investigated a ratiometric sensing system based on a benzocoumarin dye; thus, three propargyl aryl ethers bearing electronically‐different self‐immolative linkers were synthesized and their relative response rate toward Pd(0) and Pd(II) were compared. We found that the response rate became faster when the self‐immolative linker became more electron‐deficient. The best‐performing system sensed Pd(0)/Pd(II) species selectively against various other metal species, which is also capable of fluorescent imaging of Pd(0)/Pd(II) species in cells. The work provides us a clue to accelerate the catalytic depropargylation step, which, when combined with a novel fluorophore, would enable us to develop out‐performing palladium sensing systems.

Emerging contaminants (Rh, Pd, and Pt) in surface sediments from a Brazilian subtropical estuary influenced by anthropogenic activities

The concentrations of Platinum (Pt), Rhodium (Rh) and Palladium (Pd) were evaluated from a highly impacted estuary in Brazil influenced by industrial pole, highway traffic and sewage outfall. The Santos-São Vicente region presents important economic activities derived from a largest harbor of Latin America and an industrial pole surrounded by intensive highway traffic. Values of Rh varied from 0.08 to 1.7 ng g−1 with highest values at stations impacted by domestic waste. Pt ranged from 0.15 to 40.3 ng g−1 with highest concentrations located close to the ferryboat traffic. Pd levels varied from 1.05 to 22.0 ng g−1 with values >5 ng g−1 in 50% of the stations. The spatial distribution of PGEs was not always directly associated with muddy sediments, because high PGE levels found even in sandy sediments. Pollution indexes, including anthropogenic factor (AF), geoaccumulation index (Igeo), Enrichment factor (EF), and Pollution Load Index (PLI) were used for evaluating contaminant potential. Based on EF, Igeo, and PLI, 50% of samples of the sediments from Santos-São Vicente Estuarine System (SSV) were classified with significant to strong PGE contamination. All stations on the Santos Channel (SC), São Vicente Channel (SVC) and Bertioga Channel (BC) had AF higher than 80% in at least one of PGE elements, as showed in station 2A, which presented AF <50% for Rh and Pd and 86% for Pt. Despite high anthropogenic enrichment, no correlations among PGE elements were observed in surface sediments. Only two stations presented Pd/Pt, Pt/Rh, and Pd/Rh typical ratios of auto catalyst (st. 14 and Piaçaguera) both located in the vicinity of highways. This could be due to the PGE deposition process in road dust, soil, and water as well as the biogeochemical cycling of PGEs involving organic metallic and inorganic complexes formed in the estuarine and seawaters.

The synthesis and SERS study of gold-palladium asymmetric nanostructures

<p indent="0mm">Gold-palladium two-component nanostructures have attracted extensive attentions due to their synergetic coupling between optical and catalytic properties, and have shown important application potential in solar energy conversion and storage, photoelectric catalysis, photoelectric devices, biological imaging, medical diagnosis and treatment and other fields. However, the synthesis of gold-palladium nanomaterials with synergistic properties still face great challenges. The reason is that the palladium can epitaxially overgrow on the Au seed surface due to the lattice match. It means that the growth of palladium on Au seeds often leads to symmetric core-shell gold-palladium structures (Au@Pd). The Pd shell can greatly prevent the plasmonics of Au core by blocking light and deteriorating the surface plasmon resonance performance through the interface damping. One strategy is to grow ultrathin Pd shell (with thickness smaller than <sc>5 nm)</sc> to realize the synergistic coupling between plasmonics and catalysis. The other more challenging way is to break the structural symmetry to prepare Janus-type gold-palladium asymmetric nanostructures. The asymmetric spatial arrangement of the two components within one nanoparticle will significantly improve the synergistic coupling effect. In this study, two methods for preparation of gold-palladium nanostructures in solution and on solid surface respectively were developed. The concave cuboid and dumbbell-shaped nanostructures with asymmetric palladium distribution on Au nanorods were prepared by adjusting the concentration of copper ions in the Au-nanorod seed solution for the first time. It was demonstrated that copper ions can compete with CTAB to adsorb on the surface of Au nanorods, which can regulate the interfacial energy of palladium deposition on the surface of Au nanorods. Therefore, the changing of gold-palladium interfacial energy caused the growth mode to be gradually transformed from the epitaxial growth to discontinuous patch on the seed surface, leading to the generation of an array of gold-palladium asymmetric nanostructures, including gold-palladium concave cuboidal nanoparticles and dumbbell-shaped nanoparticles, where palladium was mainly grown on the two ends of Au nanorods. Besides the solution-mediated synthesis, we also developed substrate-based techniques combined colloidal chemistry to prepare gold-palladium nanostructures. This method combined the merits of substrate-based self-assembly techniques and powerful colloidal chemistry to prepare a rich class of nanostructure architectures with unique properties. The monolayer of Au-octahedron was prepared at an air-solid interface and then transfer to a silicon surface. The substrate-immobilized self-assembly monolayer was used as seeds to induce the growth of palladium by dipping into the growth solution. A series of gold-palladium nanostructures with different palladium loadings were prepared on the solid surface with a monolayer of Au-octahedron as seeds by controlling the palladium content in the growing solution. Because of the steric hindrance effect of solid surface, palladium is preferred to nucleate on the surface of Au octahedron away from solid base. Therefore, the fabricated gold-palladium nanostructures have asymmetric spatial distribution of the gold and palladium components as was demonstrated by SEM and XRD analysis. Through the study of the SERS performance of the gold-palladium nanostructures under different palladium loadings, the surface-supported gold-palladium nanostructures with optimal SERS performance was obtained. The catalytic hydrogenation of p-nitrothiophenol into p-aminothiophenol through the optimal gold-palladium asymmetric nanostructure was monitored by <italic>in</italic>-<italic>situ</italic> SERS. The experimental results showed that the asymmetric palladium nanostructures prepared in this study realized the synergistic coupling between catalytic and SERS properties. It is expected that the method to synthesize asymmetric nanostructure developed here will play an important role in the field of heterogeneous catalysis.

Electrospun ZnO/Pd Nanofibers: CO Sensing and Humidity Effect.

Variable air humidity affects the characteristics of semiconductor metal oxides, which complicates the reliable and reproducible determination of CO content in ambient air by resistive gas sensors. In this work, we determined the sensor properties of electrospun ZnO and ZnO/Pd nanofibers in the detection of CO in dry and humid air, and investigated the sensing mechanism. The microstructure of the samples, palladium content, and oxidation state, type, and concentration of surface groups were characterized using complementary techniques: X-ray fluorescent spectroscopy, XRD, high-resolution transmission electron microscopy (HRTEM), high angle annular dark field scanning transmission electron microscopy (HAADF-STEM), energy-dispersive X-ray (EDX) mapping, XPS, and FTIR spectroscopy. The sensor properties of ZnO and ZnO/Pd nanofibers were studied at 100–450 °C in the concentration range of 5–15 ppm CO in dry (RH25 = 0%) and humid (RH25 = 60%) air. It was found that under humid conditions, ZnO completely loses its sensitivity to CO, while ZnO/Pd retains a high sensor response. On the basis of in situ diffuse reflectance IR Fourier transform spectroscopy (DRIFTS) results, it was concluded that high sensor response of ZnO/Pd nanofibers in dry and humid air was due to the electronic sensitization effect, which was not influenced by humidity change.

Biomass waste rice husk derived silica supported palladium nanoparticles: an efficient catalyst for Suzuki–Miyaura and Heck–Mizoroki cross-coupling reactions

Here, we report an inexpensive, versatile, and environmentally benign biomass waste rice husk derived amorphous silica-supported palladium (PdNPs/RH-SiO2) nano-catalyst for Suzuki–Miyaura and Heck–Mizoroki cross-coupling reactions. The proposed catalyst was prepared in two steps. In the first step, amorphous SiO2 obtained by calcination of rice husk and the following deposition of palladium nanoparticles by using the chemical reduction method in the second step. The physico-chemical properties of the catalysts were investigated by N2 adsorption–desorption, XRD, XPS, 29Si CP-MAS NMR, and TEM analysis. The palladium content in the catalysts has been determined by ICP-OES analysis. The 1% PdNPs/RH-SiO2 exhibited excellent catalytic performance for Suzuki–Miyaura and Heck–Mizoroki C–C cross-coupling reactions to produce biaryl and stilbene compounds with >99% selectivity and excellent TON values (529 and 524). Furthermore, the catalyst is repeatedly used for four consecutive cycles without a significant drop in the yield.

Structure and properties of Cu-based alloys diluted by Pd and Ag

The microstructure, mechanical and electrical properties of Cu-Pd alloys (with Pd content not more than 8 at.%) and triple Cu-Pd-Ag alloys with 5 at.%Ag were studied. It was established that the strength and the recrystallization temperature of the Cu-Pd alloys increased with palladium content. A comparison of the electrical properties of these alloys when Pd content was increased from 0 to 8 at.%Pd was done. An anomaly was revealed in the Cu-5.9Pd and Cu-8Pd alloys: the plastic deformation does not lead to an increase in the electrical resistivity. It is due to the destruction of short range atomic order in the quenched Cu-Pd alloys under deformation. The alloying with silver leads to a further increase in strength with a constant electrical conductivity. It was found that annealing of the deformed Cu-Pd-Ag alloys at 200-300°C led to an increase in strength. It was shown that the effect was not related to the Pd-content and was due to silver only.

Development of Bifunctional Electrocatalyst By Palladium Deposition on Modified Perovskite La0.6Sr0.4Co0.2Fe0.8O3-Δ for Li−O2 Battery

La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) perovskites have previously emerged as efficient cathode catalysts for various electrochemical devices such as lithium-air cathode, since its superior chemical stability and mixed electron-ion conductivity. LSCF exhibits good activity for the oxygen evolution reaction (OER) as cathode catalysts. However, the activity on Oxygen Reduction Reaction (ORR) is still a barrier to be utilized as a catalyst for low-temperature electrochemical devices such as lithium-air battery. Bifunctional electrocatalyst is important to reduce the large overpotential involved the sluggish kinetics of the ORR and OER at the air electrode in lithium-air battery. In this work, palladium (Pd) contents were deposited on the nano-sized LSCF surface to improve its ORR activity in lithium-air battery. When the 20 wt.% Pd/Nano-LSCF were applied to cathode catalyst in Li-O2 battery, higher initial discharge capacity (16912 mAh g-1) compared with Nano-LSCF (6707 mAh g-1) was obtained. These results demonstrate the deposition of Pd can be an effective catalyst to enhance the ORR activity of perovskite LSCF.

Deciphering the role of amine in amino silane-functionalized Pd/rGO catalyst for formic acid decomposition at room temperature

Additive free, selective decomposition of formic acid to hydrogen and carbon dioxide at room temperature is still a challenging catalytic process which often requires noble metal catalyst (Pd, AuPd, AuPt) and sodium formate as an additive. Till date, catalyst design is targeted towards minimum noble metal usage along with incorporation of basic functionalities to produce in situ formate ion (key intermediate for dehydrogenation) from formic acid. In this work, we have studied the catalytic behaviour of amino silane-functionalized graphene oxide (GO) containing palladium nanoparticles for formic acid decomposition in ambient condition. By varying amine functionalization on GO and palladium content, the best performing catalyst was obtained with 5 wt% palladium loading. Additionally, it was observed for the first time that along with stability of a catalyst in reaction medium, its interaction with decomposed products, i.e., carbon dioxide with amine functional groups plays a crucial role in recyclability of a catalyst.