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Direct formic acid fuel cells (DFAFCs) stand out for portable electronic devices owing to their ease of handling, abundant fuel availability, and high theoretical open circuit potential. However, the practical application of DFAFCs is hindered by the unsatisfactory performance of electrocatalysts for the sluggish anodic formic acid oxidation reaction (FAOR). Palladium (Pd) based nanomaterials have shown promise for FAOR due to their highly selective reaction mechanism, but maintaining high electrocatalytic durability remains challenging. In this study, a novel Pd‐based electrocatalyst (UiO‐Pd‐E) is reported with exceptional durability and activity for FAOR, which can be attributed to the Pd nanoparticles encapsulated within a carbon framework where concurrent chemical alloying of Pd and Zr occurs. Further, the UiO‐Pd‐E demonstrates noteworthy multifunctionality in various electrochemical reactions including electrocatalytic ethanol oxidation reaction (EOR) and oxygen reduction reaction (ORR) in addition to the FAOR, highlighting its practical potentials. [ABSTRACT FROM AUTHOR]

Abstract Direct formic acid fuel cells (DFAFCs) stand out for portable electronic devices owing to their ease of handling, abundant fuel availability, and high theoretical open circuit potential. However, the practical application of DFAFCs is hindered by the unsatisfactory performance of electrocatalysts for the sluggish anodic formic acid oxidation reaction (FAOR). Palladium (Pd) based nanomaterials have shown promise for FAOR due to their highly selective reaction mechanism, but maintaining high electrocatalytic durability remains challenging. In this study, a novel Pd‐based electrocatalyst (UiO‐Pd‐E) is reported with exceptional durability and activity for FAOR, which can be attributed to the Pd nanoparticles encapsulated within a carbon framework where concurrent chemical alloying of Pd and Zr occurs. Further, the UiO‐Pd‐E demonstrates noteworthy multifunctionality in various electrochemical reactions including electrocatalytic ethanol oxidation reaction (EOR) and oxygen reduction reaction (ORR) in addition to the FAOR, highlighting its practical potentials.

Material characterization, hydrogen permeation, and separation properties of a novel ternary Pd 82 Ag 15 Y 3 membrane were evaluated by feeding single gases and several mixtures at temperature and pressure ranges of 300 – 600 °C and 1.0–3.0 bar (abs), respectively. The Pd 82 –Ag 15 –Y 3 membrane was prepared by cold rolling and was characterized by ∼38 μm of thickness. When exposed to air at different temperature and constant pressure of 1 bar, the membrane showed good thermal and chemical stability. In particular, its surface area increased from 615 μm2 at 25 °C to 685 μm2 at 500 °C indicating a potential improvement of hydrogen permeation. However, several agglomerates consisting of metal oxides were formed on the surface at the highest temperature. The temperature was -then- kept constant at 400 °C and the pressure was varied to analyze the effects of singles gases and several mixtures on the hydrogen permeation characteristics. When exposed to pure gases, such as H 2 and N 2 , the membrane showed an H 2 permeability of 9.1 × 10−11 mol m−1 s−1.Pa−0.9 and "n" value of 0.9 due to the presence of Y, while no N 2 was detected in the permeate stream, respectively. So, the membrane was considered to be completely selective towards H 2 permeation. When mixtures were used, the hydrogen permeation decreased by its original value due to the presence of other gases, such as N 2 , CH 4 , CO 2 and CO. The presence of CO particularly affected the H 2 permeating flux due to the competitive adsorption of both gases on the Pd-alloy surface. Finally, the Scanning Electron Microscope (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), Atomic Force Microscope (AFM) and X-ray diffraction (XRD) analysis were performed to observe any changes in the surface and structure of pristine and used membrane. • The Pd 82 Ag 15 Y 3 membrane showed good thermal and chemical stability when exposed to air at different temperature. • The Pd 82 Ag 15 Y 3 membrane showed higher permeability than Pd–Ag due to the presence of Y, which increased H 2 solubility. • No changes observed on the membrane's morphology with gases exposure except with O 2. • The hydrogen permeation flux decreased by 41% with CO exposure at 400 °C. [ABSTRACT FROM AUTHOR]

The effect of membrane thickness on the parameters of high-purity hydrogen production in a membranecatalytic device from a mixture of methane and water vapor has been analysed in detail using the method of mathematical simulation under standard initial conditions. A linear dependence of the average density of the hydrogen diffusion flux through the membrane on the membrane inverse thickness has been established. [ABSTRACT FROM AUTHOR]

Hydrogen-based fuels demand high-density storage that can operate at ambient temperatures. Pd and its alloys are the most studied metal hydrides for hydrogen fuel cell applications. This study presented an alternative Pd alloy for hydrogen storage that can store and release hydrogen at room temperature. The surface of the most commonly studied Pd (110) was modified with Au and Rh such that the hydrogen adsorption energy was 0.49 eV and the release temperature was 365 K. Both values are quite close to the optimal values for the adsorption energy and release temperature of a hydrogen fuel cell in real use. We further show that the modified Pd (110) surface has significantly stronger oxygen evolution reaction (OER) catalytic properties than the pure Pd (110) surface. • A novel Pd alloy structure is proposed in which hydrogen can be stored and released under ambient conditions. • Using first-principles calculations, the Pd alloy structure was designed by mixing Au and Rh on Pd (110) surface. • The hydrogen adsorption energy is 0.49 eV and 365 K is the release temperature. • Adsorption energy and release temperature are almost in the range of ideal operating conditions of the hydrogen fuel cell. [ABSTRACT FROM AUTHOR]

2D palladium nanostructures enable sensitive room‐temperature detection of H2. However, they can be limited by stability and fabrication costs. Stability may be improved by alloying Pd with other metals, while cost could be reduced by using paper as a substrate. An ultra‐low‐cost sensor using Pd alloy (PdMoY) nanosheets (NS) on paper is reported. The 2D Pd alloy nanosheets are prepared by a solution‐phase route, drop cast onto paper (≈1 × 1 cm) with silver contacts drawn on it, and dried. The same material is deposited on an interdigitated electrode (IDE). Both sensors are tested for response to hydrogen in air. The resistance of the paper‐based sensor decreased by ≈18.7% in 1% H2, which is about 40 times the response of the IDE‐based sensor. Its H2 limit of detection (1 ppm) is also lower than that of the IDE‐based sensor (5 ppm). Compared to pristine Pd NS, PdMoY NS are more stable to repeated H2 pulses without any signs of buckling or cracks. The nanosheets are also deposited by inkjet printing to produce functional sensors, providing a simple route to manufacturing of ultra‐low‐cost gas sensors for use in fuel‐cell vehicles and related infrastructure. [ABSTRACT FROM AUTHOR]

Palladium (Pd)-transition metal alloys have the potential to regulate the intermediate surface adsorption strength in oxygen reduction reactions (ORR), making them a promising substitute for platinum-based catalysts. Nonetheless, prolonged electrochemical cycling can lead to the depletion of transition metals, resulting in structural degradation and poor durability. Herein, the synthesis of alloy catalysts (Pd 25% Te 75% ) containing Pd and the metalloid tellurium (Te) through a one-step reduction method is reported. Characterizations of powder X-ray photoelectron spectroscopy, X-ray diffraction, and high-resolution transmission electron microscopy demonstrated both uniform dispersion and strong binding force of elements within the PdTe alloy, along with providing crystallographic details of associated compounds. Based on density functional theory calculations, PdTe had a more negative d-band center than that of pure Pd, which reduces the adsorption capacity between active sites and intermediates in the ORR, and therefore enhances reaction kinetics. The Pd 25% Te 75% exhibited excellent ORR activity, and its onset and half-wave potentials were ∼0.98 and ∼0.90 V, respectively, at 1600 rpm within the O 2 -saturated 1.0 M KOH. Significantly, accelerated durability tests achieved exceptional stability, and half-wave potential just decayed by 4 mV after 30000 consecutive cycles. Moreover, this study aims to promote the preparation of Pd and metalloid alloys for other energy conversion applications.

The thermobaric and concentrational stresses, which arise during the operation of a membrane element under cyclic conditions, can result in the violation of the integrity of a membrane comprising an element and in failure of the element. Studies of the effect of thermobaric cycling in a hydrogen atmosphere at operating parameters (pressure differential, temperature, time of operation) on the properties of membranes allow us to determine the optimum operation conditions of the membrane element. The stability of the Pd–6 wt % In–0.5 wt % Ru–1 wt % Co membrane structure is estimated using the studied temperature dependence of the specific hydrogen permeability of the membrane during its operation in a hydrogen atmosphere, and the possibility of efficient operation of the membrane under given conditions in a temperature range of 250–600°C is noted. The surface of the Pd–6 wt % In–0.5 wt % Ru–1 wt % Co membrane subjected to thermobaric cycling in a commercial-purity hydrogen atmosphere is studied by atomic force microscopy and X‑ray diffraction analysis. [ABSTRACT FROM AUTHOR]

A permeation probe is a useful device for detecting the atomic hydrogen flux to plasma-facing walls. Recently, we developed a new type of probe using 60Pd-40Cu alloy (PdCu) as the permeation material. The deuterium behaviors in PdCu samples were investigated using nuclear reaction analysis (NRA) and permeation observations, and the diffusion coefficient and recombination coefficients were determined from these observations. It was found that the sensitivity of a 0.02-mm-thick probe was as high as 0.5 below 473K and was independent of the incident flux. The response time at 473K was 0.41s and 1.3s under an incident flux of 1020m−2s−1 and 1019m−2s−1, respectively. Thus, we concluded that the new PdCu probe can effectively detect the incident atomic hydrogen with high sensitivity and a suitable response time.

Pd-based core-shell alloy-supported catalysts were prepared sequentially via a microwave-assisted polyol method and galvanic replacement. To investigate the effect of the core composition on the catalytic activity of such catalysts, three different Pd alloy cores (PdNi, PdCu, and PdNiCu) were prepared on carbon supports using a polyol method. Then, Pd and Ir were introduced simultaneously to form shells on the Pd alloy cores by galvanic replacement in aqueous solution, thereby producing catalysts designated as PdNi@PdIr/C, PdCu@PdIr/C, and PdNiCu@PdIr/C. X-ray diffraction revealed that all three catalysts exhibited the face-centered cubic structure of Pd without the presence of individual phases for Ni, Cu, and Ir. The core-shell structure of the Pd-based alloy nanoparticles on the carbon support was verified by the electron energy loss spectroscopy line profile of a 25 nm nanoparticle of PdNiCu@PdIr/C. Among the three Pd-based core-shell catalysts, the highest electrochemical surface area and oxygen reduction reaction (ORR) activity was observed for PdNiCu@PdIr/C. In addition, the membrane electrode assembly employing the PdNiCu@PdIr/C catalyst displayed a significantly improved voltage compared to the other two catalysts under high-temperature polymer electrolyte membrane fuel cell conditions at 150 °C. Single-cell durability tests conducted to measure the voltage change at a constant current density of 0.2 A cm −2 showed a decay ratio of 12.3 μV h −1 . These results suggest that the composition of the core in core-shell nanoparticles has an important influence on both the electronic properties in the Pd alloy core and compressive lattice strain on the PdIr shell. Control of these synergistic effects provides a new approach for developing catalysts with high ORR activity. [ABSTRACT FROM AUTHOR]

Surface segregation of a series of forty Palladium-based binary alloys has been investigated using a thermodynamic model based on an atom exchange approach. Their surface segregation behaviour, both in vacuum and in gas environments, were comprehensively estimated. The calculated results are in good agreement with the available experimental and computational data reported in literatures. Effects of mixing enthalpy, temperature, crystal orientation on the surface, elastic strain energy, adsorption and absorption of gases like H 2 , O 2 , CO have been discussed in detail. These results can be considered as basic guidelines to design novel Pd alloys for hydrogen separation membranes, sensors or catalysts. The model itself also offers a convenient and accurate routine to predict the surface segregation of other than Pd-based binary alloys in different gas atmospheres. [ABSTRACT FROM AUTHOR]

A diffusion behavior of hydrogen in a hydrogen storage alloy is affected by not only hydrogen concentration but also the stress induced by hydrogen atom expanding the lattice of the alloy. The uphill diffusion in which hydrogen diffused against the concentration gradient due to the stress has been observed. Moreover, the fugacity of hydrogen in the alloy deviates from unity significantly even at low hydrogen concentration, which decreases the flux. In this paper, the effect of the stress and the diffusion coefficient variation with the concentration on hydrogen diffusion at low concentration was investigated using the finite element analysis. As a result, the variable diffusion coefficient model combined with the stress effect showed better agreement with the experimental result than Fick's diffusion models and the constant coefficient SID model. It was concluded that the effect should be considered even if the concentration is low. [ABSTRACT FROM AUTHOR]

Dense metal membranes that are based on palladium (Pd) are promising for hydrogen separation and production due to their high selectivity and permeability. Optimization of alloy composition has normally focused on bulk properties, but there is growing evidence that grain boundaries (GBs) play a crucial role in the overall performance of membranes. The present study provides parameters and analyses of GBs in the ternary Pd-Ag-Cu system, based on first-principles electronic structure calculations. The segregation tendency of Cu, Ag, and vacancies towards 12 different coherent ∑ GBs in Pd was quantified using three different procedures for relaxation of supercell lattice constants, representing the outer bounds of infinitely elastic and stiff lattice around the GBs. This demonstrated a clear linear correlation between the excess volume and the GB energy when volume relaxation was allowed for. The point defects were attracted by most of the GBs that were investigated. Realistic atomic-scale models of binary Pd-Cu and ternary Pd-Cu-Ag alloys were created for the ∑5(210) boundary, in which the strong GB segregation tendency was affirmed. This is a starting point for more targeted engineering of alloys and grain structure in dense metal membranes and related systems.

In this study, fine, uniform nano-scale layers of Pd were deposited by an advanced sputtering system with high vacuum, high temperature, and high power to overcome the limitations of existing sputtering systems. Thin Pd films formed by continuous sputtering exhibited vertical growth, combined with the lateral growth of Pd clusters due to the improved reactivity of Pd nano-particles, the diffusion of activated Pd atoms at high temperature, and the self-catalyst effect of the porous nickel support (PNS). Additionally, uniformly dense Pd structures were formed by the successive deposition of Pd particles, and Pd clusters formed with a uniform density. A fine Pd–Au alloy membrane manufactured by this advanced sputtering system not only improved hydrogen selectivity due to the pinhole-free membrane surface but also increased hydrogen permeability because the thin film had a thickness less than 6 µm and a uniformly fine grained structure. Additionally, the Pd alloy membrane exhibited enhanced durability because the inter-diffusion of the support component to the membrane surface was prevented by the low temperature of the heat treatment for crystallization and the low alloying temperature. [ABSTRACT FROM AUTHOR]

This study aims to describe the effect of pulse shaping on the prevention of internal defects during laser welding for two dental alloys mainly used in prosthetic dentistry. Single spot, weld beads, and welds with 80 % overlapping were performed on Co-Cr-Mo and Pd-Ag-Sn cast plates with a pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG) laser. A specific welding procedure using adapted parameters to each alloy was completed. All the possibilities for pulse shaping were tested: (1) the square pulse shape as a default setting, (2) a rising edge slope for gradual heating, (3) a falling edge slope to slow the cooling process, and (4) a combination of rising and falling edges. The optimization of the pulse shape is supposed to produce defect-free welds (crack, pores, voids). Cross-section SEM observations and Vickers microhardness measurements were made. Pd-Ag-Sn was highly sensitive to hot cracking, and Co-Cr-Mo was more sensitive to voids and small porosities (sometimes combined with cracks). Using a slow cooling ramp allowed a better control on the solidification process for those two alloys always preventing internal defects. A rapid slope should be preferred for Co-Cr-Mo alloys due to its low-laser beam reflectivity. On the opposite, for Pd-Ag-Sn alloy, a slow rising slope should be preferred because this alloy has a high-laser beam reflectivity. [ABSTRACT FROM AUTHOR]

Hysteresis of electrical resistance–hydrogen (deuterium) content relationship in the α + β two-phase region of the Pd–H(D) system measured by a gas phase method was found by Sakamoto et al. [20,21], and subsequently verified and extended to Pd alloy–H(D) systems by Kibria et al. [22–28]. However, the evidence of this phenomenon is not reliable because the resistance was measured from one sample and the hydrogen content was determined from other samples in the same vessel. In this paper, it is proposed that the ‘hysteresis’ is attributed to the inequality of plateau pressures between these two sorts of samples during the α ↔ β phase transitions of the Pd–H(D) and Pd alloy–H(D) systems. Some phenomena accompanied are also discussed on this basis. [ABSTRACT FROM AUTHOR]

Abstract: Palladium membrane is the best choice for hydrogen ultra-purification; however, it suffers from difficulties such as hydrogen embrittlement and poisoning with sulfur compounds. In order to overcome these problems, a dense PdAg alloy composite membrane was synthesized using the sequential electroless plating of Pd and Ag onto a porous stainless steel. Then a thin layer of sulfur tolerant PdCu fcc phase was deposited on this layer by electroless plating, too. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were used to study lattice phase, alloying, thickness and elemental composition of the membrane. The membrane's permeation performance was tested at different temperatures between 502 and 553K and a pressure difference up to 90kPa. By lowering the temperature from 553K to 502K, the best pressure exponent changes from 0.5 to 0.7. Hydrogen permeability of 1.77×10−8 molm/m2 sPa0.5 has been obtained at a temperature of 553K. The membrane sulfur resistance was confirmed by exposure to a combined gas of H2 and H2S. [Copyright &y& Elsevier]

Abstract: In this study, the hydrogen sensing properties of nanoporous Pd–Ag and Pd–Cu alloy films based on anodic aluminum oxide (AAO) templates were investigated at various temperatures (25–100°C) and hydrogen with concentrations in the range between 250 and 5000ppm in high purity nitrogen to determine the temperature–sensitivity relationship. A hexagonally shaped AAO template of approximately 50nm in diameter and 10μm in length was fabricated as a substrate for supporting a nanoporous Pd alloy film with an approximate thickness of 80nm. The morphologies of the AAO template and the Pd alloy films were studied by scanning electron microscopy (SEM). The hydrogen sensing properties of the nanoporous Pd–Ag and Pd–Cu alloy films were measured using a transient resistance method. The sensor responses of the nanoporous Pd–Ag and Pd–Cu films on the AAO template were better than the traditional Pd–Ag and Pd–Cu thin film sensors; the sensitivities of the sensors were approximately 1.6% and 1.2%, respectively, for 1000ppm H2, and the detection limit was 250ppm at room temperature. The highest sensitivity was measured at room temperature for all alloy nanoporous sensors, and the sensitivity of the Pd–Ag nanoporous alloy was higher than that of the Pd–Cu nanoporous alloy. [Copyright &y& Elsevier]

Abstract: With the development of modern synchrotron sources, high-energy X-ray diffraction plays an important role in the residual stresses analysis of materials. This paper deals with the development of a new high-energy synchrotron X-ray diffraction (HESXRD) stress evaluation method for improving the near-surface strain measurement. For this purpose a new Monte Carlo simulation program has been developed to modelize any synchrotron radiation instrument. Futhermore conventional X-ray diffraction measurements have also been carried out after chemical etching, to define the surface and in-depth stresses of the sample, thus giving a reference to test the synchrotron radiation measurements. It has been shown that the reliability of this method is better than 5μm. This method has been applied to a machined palladium alloy (Pd–Ag–Sn) plate substrate. [Copyright &y& Elsevier]

Abstract: Carbon black (Vulcan XC72R)-supported palladium–vanadium electrocatalysts for the oxygen reduction reaction (ORR) were synthesized by wet chemical reduction of metal chloride salts. The nominal compositions of the electrocatalysts were 60:40, 70:30 and 80:20 (Pd/V atomic ratio). The electrocatalysts were treated at a range of temperatures in 10% H2 in Ar and the effect of heat treatment on particle morphology was characterised using powder X-ray diffraction and transmission electron microscopy. These analyses showed that high temperatures caused an increase in the average particle size. The electrocatalytic activities of the electrocatalysts for the ORR were determined using rotating disk electrode voltammetry, which revealed a marked enhancement in the electrocatalytic activity of the Pd70V30 electrocatalyst after heat treatment. The electrochemical stability of the electrocatalysts was examined using an accelerated stability test, which showed a loss of electrochemical surface area upon electrochemical cycling, the extent of which depended on the nominal composition of the electrocatalysts. Electrocatalyst testing after the stability test showed a loss of electrocatalytic performance and microscopic analysis revealed significant morphological changes in the electrocatalyst particle dimensions and dispersion on the carbon support after the stability test. [Copyright &y& Elsevier]

Abstract: Introducing palladium to traditional platinum-based alloy electrocatalysts offers a novel approach to develop highly efficient anode electrocatalysts for direct methanol fuel cells. In this communication, we report the preparation of thin-wall mesoporous quaternary PtPdRuOs alloy catalyst via electrochemical co-reduction of their chloride precursors all dissolved in aqueous domains of the liquid crystalline phases of an oligoethylene oxide surfactant. Scanning electron micrographs (SEM) reveal that the deposit is composed of uniform nanospheres with an average diameter of around 120nm and the average mole composition of the metal elements is Pt37Pd33Ru22Os10. Transmission electron micrographs (TEM) disclose that the nanospheres have an ordered nanostructure which is characterized by periodic pores of 3.6±0.4nm in diameter separated by walls of 2.4±0.4nm in thickness. X-ray diffraction studies signal a highly alloying degree for the four metal components in the deposit. The specific electrochemical surface area of the nanostructured powder assessed using underpotential deposited Cu stripping technique is as high as 105m2 g–1, much higher than that of unsupported precious metal catalysts prepared using standard techniques. These characters suggest that the quaternary PtPdRuOs alloy materials with high surface area and thin-wall mesoporous structure would be a novel class of promising electrocatalysts for direct methanol fuel cells. [Copyright &y& Elsevier]

Abstract: Palladium alloy composite membranes for hydrogen separation have been fabricated on a porous stainless steel (SS) support by the vacuum electrodeposition and laminating procedure of thin palladium alloy film less than 25 μm. In spite of the formation of an alloy with copper, the brittleness of the palladium-based membrane due to palladium hydride in the presence of hydrogen diffusing through the membrane was a major problem, which causes a failure of the membrane with formation of pinholes. By preparing the composite membrane without microstructural change, it is possible to obtain both high performance and stable membrane. The permeation behavior for the prepared composite membranes was measured in long-term. During permeation testing, the physical and morphological stability of the composite membranes have been observed and the long-term tests have shown very high performances above 3 months of operation. Furthermore, these composite membranes had the capability to separate hydrogen from gas mixture with complete hydrogen selectivity and can be used to produce ultra-pure hydrogen for applications in membrane reactor and so on. [Copyright &y& Elsevier]

Abstract: Copper and zinc oxide based catalysts prepared by coprecipitation were promoted with palladium and ZrO2, and their activity and selectivity for methanol oxidative reforming was measured and characterized by N2O decomposition, X-ray absorption spectroscopy, BET, X-ray photoelectron spectroscopy, X-ray diffraction, and temperature programmed reduction. Addition of ZrO2 increased copper dispersion and surface area, with little effect on activity, while palladium promotion significantly enhanced activity with little change of the catalytic structure. A catalyst promoted with both ZrO2 and palladium yielded hydrogen below 150°C. EXAFS results under reaction conditions showed that the oxidation state of copper was influenced by palladium in the catalyst bulk. A palladium promoted catalyst contained 90% Cu0, while the copper in an unpromoted catalyst was 100% Cu1+ at the same temperature. Palladium preferentially forms an unstable alloy with copper instead of zinc during reduction, which persists during reaction regardless of copper oxidation state. A 100-h time on stream activity measurement showed growth in copper crystallites and change in copper oxidation state resulting in decreasing activity and selectivity. A kinetic model of the reaction pathway showed that palladium and ZrO2 promoters lower the activation energy of methanol combustion and steam reforming reactions. [Copyright &y& Elsevier]

Abstract: Optical reflectance measurements were performed to determine the hydrogen response characteristics of 20nm thick Pd0.6Au0.4 films. The response time and signal change characteristics were determined as a function of hydrogen concentrations ranging from 0.05% to 4% in a balance of dry CO2 free air. The detection limit was determined to be 0.05%, with a corresponding response time of 130s, while at 4% hydrogen concentrations the response time was 5s at ambient temperatures. A linear decrease of both the signal change and response time was measured within an operating temperature range between 25°C and 100°C for a 1% hydrogen in air gas mixture. The sensor response dependence of the Pd0.6Au0.4 film with a change in humidity was determined between ambient levels and 95% relative humidity (RH). While the signal change was independent of humidity the response time increased due to water adsorption on the Pd alloy sensing layer. A similar increase in response time was shown for 100ppm of background CO mixed with 1% hydrogen in nitrogen at room temperature. At an elevated operating temperature of 80°C, 100ppm of CO did not affect the sensor response towards 1% hydrogen in a balance of nitrogen. Reliability tests have been performed over a 1-year time period and the sensing specifications have not drifted beyond 2% and 13% of the calibrated signal change and response time, respectively. A response time on the order of seconds and the proven stability of the high alloy content Pd thin film demonstrate the promising attributes of this material for use in an all-optical hydrogen sensor. [Copyright &y& Elsevier]

The residual stress (RS) profile state of a palladium alloy sample, used in dentistry applications, has been determined by various diffraction techniques. An additional aim of this work was to improve different experimental methods dedicated to such RS evaluation, demonstrating that the X-ray, neutron and high-energy synchrotron X-ray diffraction (HESXRD) techniques are complementary when employed in different zones of the sample. [ABSTRACT FROM AUTHOR]

Some spectroscopic analyses were carried out on the adhesive interface layers formed by cure-adhesion of natural rubber to electroless Pd and/or Pd–P alloys. The transmission electron microscopy revealed some clear images of the adhesion layer just at the interface between rubber and electroless-plating films of Pd and/or Pd–P alloys. The content ratio of Pd/S analyzed by energy dispersive X-ray spectroscopy changed gradually along the depth at the rubber–metal interface layer for Pd alloy, but was kept almost constant irrespective of depth for Pd–P alloy. [Copyright &y& Elsevier]