Pd Content Research Articles

Usability of Robinia pseudoacacia in monitoring changes and reducing airborne palladium pollution

Palladium (Pd), whose use has been increasing in recent years, is one of the heavy metals that pose a danger to the environment and human health, and it is known that heavy metals can be extremely harmful when inhaled from the air and taken into the human body. Therefore, monitoring and reducing the change of Pd pollution in the air is very important. This study aimed to determine the usability of Robinia pseudoacacia, which is grown intensively in urban areas where heavy metal pollution may be high, to monitor and reduce the change in Pd pollution in the air. Within the scope of the study, changes in Pd concentration in Robinia pseudoacacia stem sections grown in Düzce, among the 5 most polluted cities in Europe, depending on organ, direction, and age range in the last 60 years, were evaluated. As a result, it was determined that Pd pollution in the region may have been released into nature through agricultural activities or transported from much more distant sources. It was also determined that the species is not a suitable biomonitor that can be used to monitor the change in Pd pollution. Still, it is an accumulator species that is extremely suitable for reducing Pd pollution.

Porous Pd-Loaded IRMOF-9 as Highly Efficient Recyclable Material Towards the Reduction of Nitroaromatics in Aqueous Media.

Nitroaromatic compounds (NACs) cause severe hazardous impacts on human health as well as on the environment. Therefore, there is dire need to develop a robust material to reduce the toxicity of these organic pollutants. In this regard, our group developed a series of porous MOF materials viz., Pdx@IRMOF-9 (x=2 %, 5 % and 10 %) by loading different concentration of Pd(II) on IRMOF-9 and explored them towards reduction of different nitroaromatic compounds. Pd10%@IRMOF-9showed ~30 % greater efficiency for the reduction of 4-NP as compared to Pd2%@IRMOF-9. Pd10%@IRMOF-9showed excellent reduction ability (>85 %) towards 4-NP, 2-NP, 2-NA, 3-NA and 2,4-DNPH. The kinetic studies indicates that the reduction follows the pseudo-first-order kinetics. Moreover, the rate constant value for reduction of 3-NA was ~9 times higher than that of 2-NP. Based on the kinetic parameters, the t1/2 values for all the nitroaromatics have been calculated. The kinetic parameters, Km and Vmax have been calculated from double reciprocal Lineweaver-Burk plot and found to be 65.984 μM and 116×10-6 Mmin-1 respectively. Pd10%@IRMOF-9showed excellent recyclability towards the reduction of 4-NP for few consecutive cycles without any remarkable loss in its activity. Thus, highly efficient, porous and robust material for the reduction of nitroaromatic compounds in aqueous media have been demonstrated.

Styrene divinyl benzene beads (SM-2) functionalized with triisobutylphosphine sulfide for selective uptake of palladium(II) from nitric acid medium

Resins impregnated with organic extractants regarded as effective adsorbent materials due to their ability for selective sorption. These resins consist of a polymeric material that is infused with accessible organic extractants. Furthermore, these resins merge the unique properties and the distinctive characteristics of both liquid-liquid extraction and solid-liquid sorption processes. In this work, the impregnation of Styrene divinyl benzene beads (SM-2 beads) with triisobutylphosphine sulfide (TIBPS = CYANEX 471X) was prepared. A SM-2 bead functionalized with CYANEX 471X (SM-2-TIBPS beads) was characterized using scanning electron microscope (SEM) and Fourier-transform infrared spectroscopy (FT-IR) techniques and investigated for recovery and separation of palladium ions from a 3 M nitric acid solution. Various parameters were studied, as shaking time effect, nitric acid concentration, SM-2-TIBPS beads weight, Pd(II) concentration and temperature. The Pd(II)/SM-2-TIBPS sorption system has an endothermic nature and was fitted with a Langmuir isotherm model with a 0.9860 regression factor. The kinetics modeling was fitted with PSO and IPD models with regression factors of 0.9889 and 0.9959, respectively. The maximum monolayer sorption capacity of SM-2-TIBPS was found to be 17.47 ± 0.9 mg/g. The sorption of Pd(II) from different media at 3 M takes the following sequence: HNO3 > HCl > H2SO4. Desorption of about 76.38 ± 2.4% was achieved with (1 M + 1 M) of thiourea + HCl after one desorption stage. Effect of other interfering ions, as Pt(II), Pb(II), Eu(III), Cu(II), Mo(VI), Co(III), Zr(IV), Fe(III), Cd(II), and Ce(III), indicates high separation factors between Pd(II) and other investigated metal ions, which ranged from 9.4 to 35.

Palladium-Functionalized Nanostructured Nickel-Cobalt Oxide as Alternative Catalyst for Hydrogen Sensing Using Pellistors.

To meet today's requirements, new active catalysts with reduced noble metal content are needed for hydrogen sensing. A palladium-functionalized nanostructured Ni0.5Co2.5O4 catalyst with a total Pd content of 4.2 wt% was synthesized by coprecipitation to obtain catalysts with an advantageous sheet-like morphology and surface defects. Due to the synthesis method and the reducible nature of Ni0.5Co2.5O4 enabling strong metal-metal oxide interactions, the palladium was highly distributed over the metal oxide surface, as determined using scanning transmission electron microscopy and energy-dispersive X-ray investigations. The catalyst tested in planar pellistor sensors showed high sensitivity to hydrogen in the concentration range below the lower flammability limit (LFL). At 400 °C and in dry air, a sensor response of 109 mV/10,000 ppm hydrogen (25% of LFL) was achieved. The sensor signal was 4.6-times higher than the signal of pristine Ni0.5Co2.5O4 (24.6 mV/10,000 ppm). Under humid conditions, the sensor responses were reduced by ~10% for Pd-functionalized Ni0.5Co2.5O4 and by ~27% for Ni0.5Co2.5O4. The different cross-sensitivities of both catalysts to water are attributed to different activation mechanisms of hydrogen. The combination of high sensor sensitivity to hydrogen and high signal stability over time, as well as low cross-sensitivity to humidity, make the catalyst promising for further development steps.

Pd modified by Fe-Nx confined in N-doped carbon with hierarchical mesoporous structure for the highly efficient semi-hydrogenation of phenylacetylene

The removal of small amounts of phenylacetylene from styrene is a crucial step in the production of high-quality styrene feedstocks. In the presence of a large amount of styrene and a small amount of phenylacetylene, achieving and maintaining high selectivity of styrene remains a significant challenge. In this work, a catalyst denoted as Pd1.25-Fe-N-C/VC was designed and synthesized with remarkably low Pd loading (the actual Pd content was 0.96 wt%). The catalyst exhibited a satisfactory selectivity for styrene (>95 %) and maintained high selectivity levels (>90 %) in the semi-hydrogenation of phenylacetylene even with prolonged reaction time. Pd nanoparticles (NPs) were well distributed and securely anchored onto the Fe-N-C/VC support with a hierarchical mesoporous structure, which obtained from the pyrolysis of a hexagonal star-like Fe-doped zeolitic imidazolate framework with vitamin C surfactant (Fe-doped ZIF/VC). The remarkable catalytic properties may be partly ascribed to the effective synergy effect of the uniformly well-dispersed Fe-Nx (x represents the coordination number) with Pd active centers, which could modulate the adsorption kinetics of the reactant alkynes and alkenes and thus enhancing the selectivity towards styrene. Meanwhile, the hierarchical mesoporous structure is beneficial for the mass transfer, which can effectively promote the interactions between the reactants and active centers. Possible mechanism for the selective hydrogenation of phenylacetylene catalyzed by Pd1.25-Fe-N-C/VC was also illustrated. Moreover, the Pd1.25-Fe-N-C/VC catalyst exhibited sustained catalytic activity and selectivity even after four continuous cycle tests, showing notable reusability and stability. This work may offer a promising approach for creating highly efficient Pd-based catalysts with remarkably low Pd loading for phenylacetylene semi-hydrogenation.

Remarkable improvement in the NOx storage ability of Pd/SSZ-13 zeolite PNA via a facile pretreatment strategy

A facile strategy was employed to pretreat Pd/SSZ-13 zeolite obtained via the initial-impregnated method under a microwave field, aiming to greatly enhancing the NOx storage-release ability. By investigating the effect of microwave treatment parameters (power, atmosphere and time) on the improvement of PNA performance, the optimal conditions were determined (175 W, 10 % O2/N2, 15 min). Under these conditions, the Pd/SSZ-13 exhibited an enhanced NOx adsorption and desorption amount to 2.60 and 2.38 times, respectively, compared to the untreated sample after three cycles of NO-TPD. Deeper insights into the variations in Pd/SSZ-13 properties induced by the microwave radiation were clarified through a series of characterizations. The micropore surface area of Pd/SSZ-13 zeolite activated by microwave increased by 3.91 %, and the micropore volume also improved by 3.85 %, which might facilitate the adhesion of more active Pd species to the materials surface, and aid in the dispersion of PdOx clusters into the zeolite channels. After microwave activation, the average particle size of Pd decreased from 10.09 nm to 7.08 nm. Particularly, the content of Pd(II) species such as Pd2+, [Pd(OH)]+ and PdO as active NOx adsorption sites enhanced from 66.68 % to 68.93 %. Additionally, the microwave treatment not only increased the number of Lewis and Brønsted acid sites, but also strengthened the interaction between NOx molecules and the zeolite skeleton. The above reasons collectively promoted the NOx storage-release properties of Pd/SSZ-13 zeolite, showing that the microwave pretreatment is a highly efficient strategy for improving the performance of PNA materials.

Enhanced thermoelectric power factor of magnetron Co-sputtered Pd-added Bi2Te3 thin films

The study on Pd-added Bi2Te3 thin films involved the preparation of these films using the co-magnetron sputtering technique. The process included fixing the Bi:Te (2:3) target at 30 W of pulsed dc-power while varying the Pd target on the sputtering power in a range of 0–12 W. All deposited film thicknesses were maintained at 500 nm. The investigation of the thermoelectric power factor (PF) of thin films with varying Pd-adding contents revealed interesting results. The Pd contents were increased by increasing the sputtering power on the Pd target. The PdTe2 phase was initiated, starting at 4 W of Pd sputtering power, resulting in a heterogeneous alloy of Bi2Te3 and PdTe2 phase. The increase in the Pd content led to a reduction in the electrical resistivity. At the same time, an appropriate Pd-adding concentration could cause the rise of the Seebeck coefficient and power factor. The maximum power factor of 3.06 mW m−1 K−2 (ρ = 14.63 μΩ m, S = −212 μV K−1) at room temperature was achieved on a Pd-added Bi2Te3 thin film (Pd-4W). This finding underscores the potential of Pd's most appropriate adding content into Bi2Te3 thin films for thermoelectric energy harvesting applications.

Unravelling charge carrier dynamics for enhancement of photocatalytic performance in Pd/MoS2 nanocomposites for water remediation of real-world pollutants

In this study, Pd/MoS2 nanocomposites were successfully synthesized incorporating Pd nanoparticles into three-dimensional (3D) flower-like MoS2 nanostructures. The controlled introduction of Pd was aimed to optimize the photocatalytic performance of the resulting nanocomposites, which exhibited exceptional efficiency in degrading various organic pollutants and antibiotic tetracycline (TC) under simulated solar light irradiation. The nanocomposites with an optimized Pd concentration of 2.5 % demonstrated outstanding photocatalytic efficiency, achieving the degradation of Rhodamine B (RhB), Methylene blue (MB), TC by 98 %, 98 %, and 96 %, respectively, with specific interval of 40, 30 and 60 min. The reaction rate constant of the Pd/MoS2 nanocomposites was measured to be 0.7798 min−1 using pseudo first-order rate kinetics. The value is about 19 times higher than that of pure MoS2 (0.00414 min−1) for degradation of RhB. The improved photocatalytic performance of these nanocomposites can be attributed to several factors. Firstly, the incorporation of Pd nanoparticles substantially enhanced their light absorption capabilities, leading to an overall increase in photocatalytic efficiency. Moreover, the presence of Pd contributed to a large surface area, further enhancing the nanocomposite's photocatalytic potential. Importantly, the formation of a built-in electric field at Pd/MoS2 interface facilitated the efficient separation of the electron-hole pairs, extending the life time of these photoinduced charge carriers. This study offers valuable insights into development of MoS2-based photocatalyst, which hold significant promise for addressing water pollution challenges and making substantial contributions to the field of water purification and environmental remediation.

Change of composition and surface plasmon resonance of Pd/Au core/shell nanoparticles triggered by CO adsorption.

Controlling composition and plasmonic response of bimetallic nanoparticles (NPs) is of great relevance to tune their catalytic activity. Herein, we demonstrate reversible composition and plasmonic response transitions from a core/shell to a bimetallic alloyed palladium/gold NP triggered by CO adsorption and sample temperature. The use of self-organized growth on alumina template film allows scrutinizing the impact of core size and shell thickness onto NP geometry and plasmonic response. Topography, molecular adsorption, and plasmonic response are addressed by scanning tunneling microscopy, vibrational sum frequency generation (SFG) spectroscopy, and surface differential reflectance spectroscopy, respectively. Modeling CO dipolar interaction and optical reflectivity corroborate the experimental findings. We demonstrate that probing CO adsorption sites by SFG is a remarkably sensitive and relevant method to investigate shell composition and follow in real-time Pd atom migration between the core and the shell. Pd-Au alloying is limited to the first two monolayers of the shell and no plasmonic response is found, while for a thicker shell, a plasmonic response is observed, concomitant with a lower Pd concentration in the shell. Above 10-4mbar, at room temperature, CO adsorption triggers the shell restructuration, forming a Pd-Au alloy that weakens the plasmonic response via Pd migration from the core to the shell. NP annealing at 550K, after pumping CO, leads to the desorption of remaining CO and gives enough mobility for Pd to migrate back inside the core and recover a pure gold shell with its original plasmonic response. This work demonstrates that surface stoichiometry and plasmonic response can be tuned by using CO adsorption and NP annealing.

Visible-light induced effective and sustainable remediation of nitro organics pollutants using Pd-doped ZnO nanocatalyst

Nitroaromatic compounds represent a class of highly toxic pollutants discharged into aquatic environments by various industrial activities, posing significant threats to ecological integrity and human health due to their persistent and hazardous nature. In this study, Pd-doped ZnO nanoparticles were investigated as a potential solution for the degradation of nitro organics, offering heightened photocatalytic efficacy and prolonged stability. The synthesis of Pd-doped ZnO NPs was achieved via the hydrothermal method, with subsequent analysis through XRD spectra and XPS confirming successful Pd doping within the ZnO matrix. Characterization through FESEM and HRTEM unveiled the heterogeneous morphologies of both undoped and Pd-doped ZnO nanoparticles. Additionally, UV–vis and PL spectroscopy provided insights into the optical properties, chemical bonding, and defect structures of the synthesized Pd-doped ZnO NPs. Pd doping induces a redshift in ZnO’s absorption spectra, reducing the bandgap from 3.12 to 2.94 eV as Pd concentration rises from 0 to 0.2 wt.%. The photocatalytic degradation, following pseudo-first-order kinetics, achieved 90% nitrobenzene abatement (200 µg/L, pH 7) under visible light within 320 min with a catalyst loading of 16 µg/mL. The photocatalytic efficacy of 0.08 wt% Pd-doped ZnO (k = 0.058 min⁻1) exhibited a 25-fold enhancement compared to bare ZnO (k = 3.1 × 10–4 min-1). Subsequent quenching and ESR experiments identified hydroxyl radicals (OH•) as the predominant active species in the degradation mechanism. Mass spectrometry analysis unveiled potential breakdown intermediates, illuminating a plausible degradation pathway. The investigated Pd-doped ZnO nanoparticles demonstrated reusability for up to five successive treatment cycles, offering a sustainable solution to nitro organics contamination challenges.

Ordered-Phase Equilibria in the Eutectoid Region of Bulk Fe-Pd

This report is the first analysis of the coexistence and microstructure of the equilibrium phases in the Fe-Pd L10 + L12 eutectoid region. Coexistence of L10 + L12 is observed at higher temperatures (650 ∘C\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^\\circ {\ ext{C}}$$\\end{document}), resulting in L10 polytwin plates with internal boundaries that are decorated by L12. For higher Pd content, the L10 plates are embedded in an extended L12 matrix, but the L12 wetting layers still persist. For aging at low temperatures (525 ∘C\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^\\circ {\ ext{C}}$$\\end{document}), L1’ + L12 coexistence is observed, but the microstructure is essentially similar, except that L10 is replaced by L1’. The two-phase region is found to be much narrower than reported in published phase diagrams, of order 0.6 to 1 at pct in extent. There may be a further re-entrant narrowing below the L1’ formation temperature. This work establishes L1’ as a phase distinguishable from both L10 and L12, but does not yet prove that L1’ is an equilibrium phase. The preferred formation of L1’ at lower temperatures may relate both to stability conferred by overall ferrimagnetic interactions, and perhaps by kinetics, where L1’ should have a reduced nucleation barrier from A1 relative to L10.

Pd Nanoparticle Supported on N‐Doped Carbon Derived from Sodium Alginate/Melamine Blends as Efficient Heterogeneous Catalyst for Heck Reactions

AbstractN‐doped porous carbon shows great potential in the field of heterogenous supports due to its high porosity, large surface area, rich active sites, and strong chelation with catalytic active metals species. Herein, we successfully prepared a novel N‐doped porous carbon derived from sodium alginate/melamine blends (SAMNC) with different mass ratio through a simple carbonization and activation process. Hierarchical porous structure of the derived N‐doped carbon has been confirmed with the SEM, TEM, and N2 adsorption characterization. After Na2PdCl4 solution impregnation and further reduction process, Pd0 nanoparticles have been uniformly immobilized on the SAMNC support to produce novel Pd@SAMNC catalyst. The optimal Pd@SAMNC‐0.6 possesses a high N content (5.13%), Pd content (5.90%), large BET specific surface area of 1884.5 m2·g−1. Positron annihilation lifetime spectroscopy (PALS) investigation of the porous carbon materials provided the sub‐nano level microporous information proofs of Pd@SAMNC‐0.6 had the capability to provide more active sites for reactions than commercial Pd supported on activated carbon (Pd@AC). Pd@SAMNC‐0.6 catalyst showed superior catalytic efficiency in Heck coupling reaction between aromatic halides and alkenes and can be recycled for 17 runs without significant decrease in catalytic efficiency.

Study on the Irradiation Evolution and Radiation Resistance of PdTi Alloys.

Medium-entropy alloys (MEAs) exhibit exceptional mechanical properties, thermal properties, and irradiation resistance, making them promising candidates for aerospace and nuclear applications. This study utilized molecular dynamics simulations to examine the defect behavior in PdTi alloys under various irradiation conditions. Simulations were performed using the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) with the modified embedded-atom method (MEAM) potential to describe interatomic interactions. Various temperatures, primary knock-on atom (PKA) energies, and elemental ratios were tested to understand the formation and evolution of defects. The results show that compared to pure Pd, PdTi alloys with increased entropy exhibit significantly enhanced irradiation resistance at higher temperatures and PKA energies. This study explored the impact of different elemental ratios, including Pd, PdTi1.5, PdTi, and Pd1.5Ti. Findings indicate that increasing the Pd concentration enhances the alloy's irradiation resistance, improving mobility and recombination rates of defect clusters. A one-to-one Pd-to-Ti ratio demonstrated optimal performance. Temperature analysis revealed that at 300 K and 600 K, PdTi alloys exhibit excellent irradiation resistance at a PKA energy of 30 keV. However, as the temperature rises to 900 K, the irradiation resistance decreases slightly, and at 1200 K, the performance is likely to decline further. This study offers some useful insights into the irradiation evolution and radiation resistance of PdTi medium-entropy alloys, which may help inform their potential applications in the nuclear field and contribute to the further development of MEAs in this area.

Photocatalytic Methanol Dehydrogenation Promoted Synergistically by Atomically Dispersed Pd and Clustered Pd.

Supported metal in the form of single atoms, clusters, and particles can individually or jointly affect the activity of supported heterogeneous catalysts. While the individual contribution of the supported metal to the overall activity of supported photocatalysts has been identified, the joint activity of mixed metal species is overlooked because of their different photoelectric properties. Here, atomically dispersed Pd (Pd1) and Pd clusters are loaded onto CdS, serving as oxidation and reduction sites for methanol dehydrogenation. The Pd1 substitutes Cd2+, forming hole-trapping states for methanol oxidation and assisting the dispersion of photodeposited Pd clusters. Therefore, methanol dehydrogenation on CdS with supported Pd1 and Pd clusters exhibits the highest turnover frequency of 1.14 s-1 based on the Pd content and affords H2 and HCHO with a similar apparent quantum yield of 87 ± 1% at 452 nm under optimized reaction conditions. This work highlights the synergistic catalysis of supported metal for improved photocatalytic activity.

Synthesis and catalytic activity of core-shell gold-palladium nanoworms towards the catalytic reduction of 4-nitrophenol and methyl orange

The Au-Pd core–shell nanostructures have gained attention as a promising catalyst and exhibit outstanding stability and selectivity in pivotal chemical reactions. This work demonstrates a facile seed-mediated approach for depositing the shell of Pd on worm-shaped Au nanostructures. The control over Pd content on Au nanoworms (NWs) was achieved by adjusting the concentration of tetrachloropalladic acid (H2PdCl4) in the deposition solution. The bent morphology, surface roughness, and polycrystalline structure of the Au NWs ensured that at lower H2PdCl4 concentrations, Pd formed an island-like structure on the Au NWs’ surface. In contrast, increasing the H2PdCl4 concentration led to the formation of a complete Pd shell encasing the Au NWs. The catalytic activity of the Au-Pd core–shell (Pd@Au) NWs exhibited a significant improvement compared to uncoated Au NWs, which has been attributed to the synergetic effect of the two metals. However, it was observed that an optimum Pd-coating was necessary to obtain the best catalytic performance and a further increase in Pd content led to the degradation of the catalytic activity. Specifically, the rate constant of the reduction reactions of 4-nitrophenol (4-NP) and methyl orange (MO) was increased by 6.3 and 3.1 folds, respectively, for the optimized Pd@Au NWs.

Enhanced low-temperature catalytic activity and stability in methane combustion of Pd−CeO2 nanowires@SiO2 by Pt dispersion

The long-standing contradiction between low-temperature activity and high-temperature stability is one of the difficulties in catalytic combustion of low-concentration methane. The traditional Pd−CeO2 catalyst system has been applied to the oxidation of methane with low concentrations. However, the problem of sintering at high temperatures still exists. In this work, we prepared the Pt-modified Pd−CeO2 nanowires (NW) sample (in which the actual Pt, Pd, and Ce contents were 0.12, 0.86, and 9.8 wt%, respectively) using the one-pot reverse-micelle emulsion method. It was found that Pt-Pd−CeO2NW@SiO2 showed the highest low-temperature catalytic activity at a space velocity of 20,000 mL/(g h) and the best water resistance and high-temperature stability in the combustion of methane. The T50 % and T90 % (the temperatures for achieving methane conversions of 50 and 90 %) were 298 and 342 ℃, respectively, methane reaction rate at 270 ℃ was 0.49 μmol/(gcat s), and turnover frequency (TOF) at 270 °C was 0.198 s−1 over Pt-Pd−CeO2NW@SiO2; whereas over Pd−CeO2NW@SiO2 (in which the actual Pd and Ce contents were 0.82 and 10.6 wt%, respectively), the T50 % and T90 % were 360 and 420 ℃, respectively, methane reaction rate at 270 ℃ was 0.074 μmol/(gcat s), and TOF at 270 °C was 0.032 s−1. The introduction of the highly dispersed Pt to Pd−CeO2NW@SiO2 could effectively increase the PdOx sites of unsaturated coordination through the electron-donating interaction of the Pt with PdO, which played an important role in activating the C−H bonds in methane. In addition, the unique structure of encapsulation also rendered the Pt-Pd−CeO2NW@SiO2 sample to possess good water resistance and thermal stability in methane combustion. We are sure that the present work provides a possibility for developing the catalysts with stable catalytic and water-resistant performance at low and high temperatures in the combustion of methane.

Composition-dependent reversal of anomalous Hall effect in Co1-xPdx single layer

We report a composition-dependent reversal of the anomalous Hall effect (AHE) in Co1-xPdx single layers. As the Pd concentration increases, the AHE signal gradually diminishes and flips to negative polarity. Our study reveals that the competition between the extrinsic skew scattering and intrinsic contributions governing the sign reversal, accompany the rising Pd concentration. This work sheds light on the AHE mechanism in magnetic single layers with AHE reversal and paves the way for exploring novel spintronic phenomena.

Au@AuPd Core-Alloyed Shell Nanoparticles for Enhanced Electrocatalytic Activity and Selectivity under Visible Light Excitation.

Plasmonic catalysis has been employed to enhance molecular transformations under visible light excitation, leveraging the localized surface plasmon resonance (LSPR) in plasmonic nanoparticles. While plasmonic catalysis has been employed for accelerating reaction rates, achieving control over the reaction selectivity has remained a challenge. In addition, the incorporation of catalytic components into traditional plasmonic-catalytic antenna-reactor nanoparticles often leads to a decrease in optical absorption. To address these issues, this study focuses on the synthesis of bimetallic core@shell Au@AuPd nanoparticles (NPs) with ultralow loadings of palladium (Pd) into gold (Au) NPs. The goal is to achieve NPs with an Au core and a dilute alloyed shell containing both Au and Pd, with a low Pd content of around 10 atom %. By employing the (photo)electrocatalytic nitrite reduction reaction (NO2RR) as a model transformation, experimental and theoretical analyses show that this design enables enhanced catalytic activity and selectivity under visible light illumination. We found that the optimized Pd distribution in the alloyed shell allowed for stronger interaction with key adsorbed species, leading to improved catalytic activity and selectivity, both under no illumination and under visible light excitation conditions. The findings provide valuable insights for the rational design of antenna-reactor plasmonic-catalytic NPs with controlled activities and selectivity under visible light irradiation, addressing critical challenges to enable sustainable molecular transformations.

Study on the Gas-Chromic Character of Pd/TiO2 for Fast Room-Temperature CO Detection.

As a widely used support, TiO2 has often been combined with Pd to form highly sensitive gas-chromic materials. Herein, we prepared a series of Pd/TiO2 catalysts with different Pd content (from 0.1 to 5 wt.%) by the impregnation method for their utilization in fast room-temperature CO detection. The detection was simply based on visible color change when the Pd/TiO2 was exposed to CO. The sample with 1 wt.% Pd/TiO2 presented an excellent CO gasochromic character, associated with a maximum chromatic aberration value of 90 before and after CO exposure. Systematic catalyst characterizations of XPS, FT-IR, CO-TPD, and N2 adsorption-desorption and density functional theory calculations for the CO adsorption and charge transfer over the Pd and PdO surfaces were further carried out. It was found that the interaction between CO and the Pd surface was strong, associated with a large adsorption energy of -1.99 eV and charge transfer of 0.196 e. The color change was caused by a reduction in Pd2+ to metallic Pd0 over the Pd/TiO2 surface after CO exposure.

Usability of Cedrus atlantica in monitoring changes and reducing airborne palladium pollution

Heavy metal pollution has become a global problem threatening the health of humans and other living things. It is crucial to monitor the changes in air concentrations and reduce pollution, mainly due to the potential harm of heavy metals taken into the body by inhalation. For these purposes, plants have begun to be used extensively as biomonitors or accumulators. However, since each heavy metal accumulates in different plants at different levels, the appropriate biomonitor or accumulator species for each heavy metal must be determined separately. This study aimed to assess the usability of Cedrus atlantica, grown in Düzce, where heavy metal pollution is at high levels, for monitoring and reducing the change in palladium (Pd) pollution in the air. Within the scope of the study, changes in Pd concentration in Cedrus atlantica stem sections grown in Düzce, which is among the five most polluted cities in Europe, depending on organ, direction, and age range in the last 60 years, were evaluated. As a result, it was determined that Pd pollution in the region has increased significantly in recent years, and traffic density is thought to be effective in this increase. It was also determined that Cedrus atlantica is a highly suitable species for monitoring the changes in Pd pollution and reducing pollution.