Pd Particles Research Articles

Heterogeneous activation of self-generated H2O2 by Pd@UiO-66(Zr) for trimethoprim degradation: Efficiency and mechanism

The Fenton reaction is recognized as an effective technique for degrading persistent organic pollutants, such as the emerging pollutant trimethoprim (TMP). Recently, due to the excellent reducibility of active hydrogen ([H]), Pd–H2 has been preferred for Fenton-like reactions and the specific H2 activation of Pd-based catalysts. Herein, a heterogeneous Fenton catalyst named the hydrogen-accelerated oxygen reduction Fenton (MHORF@UiO-66(Zr)) system was prepared through the strategy of building ships in the bottle. The [H] has been used for the acceleration of the reduction of Fe(III) and self-generate H2O2. The systematic characterization demonstrated that the nano Pd0 particle was highly dispersed into the UiO-66(Zr). The results found that 20 mg L−1 of TMP was thoroughly degraded within 90 min in the MHORF@UiO-66(Zr) system under conditions of initial pH 3, 30 mL min−1 H2, 2 g L−1 Pd@UiO-66(Zr) and 25 μM Fe2+. The hydroxyl radical as well as the singlet oxygen were evidenced to be the main reactive oxygen species by scavenging experiments and electron spin resonance. In addition, both reducing Fe(III) and self-generating H2O2 could be achieved due to the strong metal-support interaction (SMSI) between the nano Pd0 particles and UiO-66(Zr) confirmed by the correlation results of XPS and calculation of density functional theory. Finally, the working mechanism of the MHORF@UiO-66(Zr) system and the possible degradation pathway of the TMP have been proposed. The novel system exhibited excellent reusability and stability after six cyclic reaction processes.

In situ photodeposition of ultra-small palladium particles on TiO2.

In situ and operando investigation of photocatalysts plays a fundamental role inunderstanding the processes of active phase formation and the mechanisms ofcatalytic reactions, which is crucial for the rational design of more efficient materials. Using a custom-made operando photocatalytic cell, an in situ procedure to follow the formation steps of Pd/TiO2 photocatalyst by synchrotron-based X-ray absorption spectroscopy (XAS) is proposed. The procedure resulted in the formation of ∼1 nm Pd particles with a much narrower size distribution and homogeneous spreading over TiO2 support compared with the samples generated in a conventional batch reactor. The combination of in situ XAS spectroscopy with high-angle annular dark-field scanning transmission electron microscopy demonstrated the formation of single-atom Pd(0) sites on TiO2 as the initial step of the photodeposition process. Palladium hydride particles were observed for all investigated samples upon exposure to formic acid solutions.

Large-scale growth of MoS2 hybrid layer by chemical vapor deposition with nanosheet promoter

Molybdenum disulfide (MoS2) serves as the representative transition metal dichalcogenide material, showing promise for diverse applications owing to its outstanding properties. Extensive research has been conducted on the growth of large-scale MoS2 films using chemical vapor deposition (CVD) with seeding accelerators for various device applications. In this study, we investigated the growth of large-scale MoS2 films for potential applications, in which our approach utilized CVD with a homogeneous nanosheet promoter (MoS2 flakes) and effectively minimized residue creation. Optical and structural analyses confirmed the successful synthesis of a large-scale MoS2 layer. Moreover, the decoration of metallic nanoparticles on the MoS2 surface was employed to enhance the functionalities of application devices such as optical sensors and gas sensors. The capability of MoS2 to act as a nucleation site for nanoparticles during synthesis offered an intriguing pathway for augmenting the attachment and performance of nanoparticles on the MoS2 surface. The photodetector, integrating a hybrid MoS2 layer and Cu nanoparticles, exhibited superior photodetection properties, attributed to the increased excitons at the interface between the metal electrodes and MoS2 films. Furthermore, in order to enhance the characteristics of the gas sensor, Pd nanoparticles were incorporated during the synthesis of MoS2 layers. This dynamic interface between Pd particles and MoS2 films presents an opportunity to explore novel materials with enhanced catalytic properties.

Ethylenediamine-mediated synthesis of Pd-based catalysts with enhanced electrocatalytic performances towards formic acid oxidation

Pd-based anode catalysts with superior activity are urgent for formic acid oxidation to further boost the direct formic acid fuel cells (DFAFCs) technologies. Herein, a strategy of ethylenediamine (EDA) modified Pd/C catalyst was developed by two main steps of EDA adsorbed on Vulcan XC-72 carbon by impregnation and Pd nanoparticles loaded on the freeze-dried C-EDA supports by liquid reduction method. The effects of sweep rates and concentrations of EDA on the formic acid electrooxidation were systematically studied. Results showed that the above parameter was optimized as the concentration of EDA of 0.1 mol L−1. Pd nanoparticles with even distribution were fabricated and particle sizes were in the range of 3.5–4.2 nm. In addition, Pd particle size became smaller with the addition of EDA, suggesting that EDA could induce the generation of smaller Pd. Electrochemical measurements demonstrated that the electrocatalytic activity of Pd/C-0.22EDA (1021 mA mg−1) with optimized modification concentration was improved as a factor of 3.82 than that of Pd/C (267 mA mg−1). An enhanced stability (about 41 times higher than Pd/C) and faster charge-transfer kinetics of formic acid electrooxidation were observed for Pd/C-0.22EDA catalyst. CV and CA measurements showed that the most active catalyst was made of the smallest (3.5 nm) Pd nanoparticles for Pd/C-0.22EDA catalyst. The better electrocatalytic performances of Pd/C-0.22EDA might be ascribed to evenly dispersed Pd with relatively smaller particle size, electron regulation between Pd and amine group as well as stable Pd structure.

Development of a Novel Structured Mesh-Type Pd/γ-Al2O3/Al Catalyst on Nitrobenzene Liquid-Phase Catalytic Hydrogenation Reactions

Nitrobenzene liquid-phase catalytic hydrogenation is commonly regarded as one of the most effective technologies for aniline production. The traditional granular catalysts have the disadvantages that the reactor bed pressure drop is large and the mass transfer efficiency between gas and liquid phases is low. In this study, a novel structured mesh-type Pd/γ-Al2O3/Al catalyst was prepared by anodic oxidation and pore structures of γ-Al2O3/Al supports were constructed by acid pore-widening treatments. The results showed that acid pore-widening treatments can improve the pore size of γ-Al2O3/Al supports; the support with HNO3 pore-widening treatment exhibited the largest pore size, being enlarged from 3.7 nm to 4.6 nm. The Pd/γ-Al2O3/Al catalysts prepared with different acid pore-widening treatment supports contribute to the increased active metal Pd loading, more Pd0 content, and better dispersion of the Pd particles. The catalyst prepared with HNO3 pore-widening treatment support exhibited the largest active metal Pd loading, enlarging from 1.82% to 1.95%, the largest Pd0 content being enlarged from 52.1% to 58.5% and the smallest Pd particle size being reduced from 103 nm to 41 nm, resulting in the highest nitrobenzene conversion, increasing from 67.2% to 74.3%. Eventually, we calculated that the pressure drop of structured catalysts was 1/72 of that of granular catalysts, resulting in a better diffusion of the H2 through nitrobenzene solution to active sites on the catalyst surface and a significant increase in the catalytic activity.

Dual functionalized Co3O4 porous cages with Pd and Co-MOF for acetone gas sensing under high humidity

Metal oxide semiconductor (MOS) gas sensors play a crucial role in gas sensors. However, the effect of higher ambient humidity on the sensitivity of MOS gas sensors is still largely an unsolved problem, limiting the application areas of sensors. In this work, an ultra-stable and sensitive acetone gas sensor based on dual functionalized Co3O4 porous cages with Pd and Co-MOF at high humidity is reported. The dual functionalized porous cages are made of MOF-derived Co3O4 porous cages substrate, Pd particles and hydrophobic Co-MOF coatings. The prepared porous cages composite exhibits humidity-independent and highly sensitive gas-sensing behavior to acetone under 70–90 % relative humidity (RH). The results indicate that the hydrophobic Co-MOF coatings not only offer excellent anti-humidity, but also show the ability of enrichment of low concentration acetone gas molecules, thus improving the sensitivity and response time of acetone detection. Meanwhile, due to the electronic spillover effect of Pd, porous cages composite possesses remarkable properties of high sensitivity, short response and recovery time, as well as low working temperature. The unique sensing characteristic makes the dual functionalized porous cages composite sensor a potential candidate for reliable noninvasive diagnosis of diabetes via exhaled breath analyses.

Phosphorus-Modified Palladium and Tungsten Carbide/Mesoporous Carbon Composite for Hydrogen Oxidation Reaction of Proton Exchange Membrane Fuel Cells.

A composite material of tungsten carbide and mesoporous carbon was synthesized by the sol-gel polycondensation of resorcinol and formaldehyde, using cetyltrimethylammonium bromide as a surfactant and Ludox HS-40 as a porogen, and served as a support for Pd-based electrodes. Phosphorus-modified Pd particles were deposited onto the support using an NH3-mediated polyol reduction method facilitated by sodium hypophosphite. Remarkably small Pd nanoparticles with a diameter of ca. 4 nm were formed by the phosphorus modification. Owing to the high dispersion of Pd and its strong interaction with tungsten carbide, the Pd nanoparticles embedded in the tungsten carbide/mesoporous carbon composite exhibited a hydrogen oxidation activity approximately twice as high as that of the commercial Pt/C catalyst under the anode reaction conditions of proton exchange membrane fuel cells.

One-Pot Synthesis of Pd Nanoparticles Supported on Carbide-Derived Carbon for Oxygen Reduction Reaction.

We explored two methods for synthesizing Pd nanoparticles using three different carbide-derived carbon (CDC) support materials, one of which was nitrogen-doped. These materials were studied for oxygen reduction reaction (ORR) in 0.1 M KOH solution, and the resulting CDC/Pd catalysts were characterized using TEM, XRD, and XPS. The citrate method and the polyol method using polyvinylpyrrolidone (PVP) as a capping agent were employed to elucidate the impact of the support material on the final catalyst. The N-doping of the CDC material resulted in smaller Pd nanoparticles, but only in the case of the citrate method. This suggests that the influence of support is weaker when using the polyol method. The citrate method with CDC1, which is predominantly microporous, led to a higher degree of agglomeration and formation of larger particles in comparison to supports, which possessed a higher degree of mesoporosity. We achieved smaller Pd particle sizes using citrate and NaBH4 compared to the ethylene glycol PVP method. Pd deposited on CDC2 and CDC3 supports showed similar specific activity (SA), suggesting that the N-doping did not significantly influence the ORR process. The highest SA value was observed for CDC1/Pd_Cit, which could be attributed to the formation of larger Pd particles and agglomerates.

Pd/TiO2 decorated carbon fibers as an efficient anode catalyst for methanol electro‐oxidation

AbstractIn this study, Pd/TiO2 decorated carbon nanofibers (Pd/TiO2@CNFs) and Pd@CNFs were prepared by the impregnation method for application in direct methanol fuel cells (DMFCs). Pd and TiO2 particles were supported on the surface of carbon fibers. Noticeably, When the mass fraction of PdCl2 added is 4%, the Pd@CNFs catalyst (Pd‐4@CNFs) showed higher electrocatalytic activity and stability, which were about 28.4 and 13.2 times higher than those of commercial Pd/C catalyst, respectively. On the basis of Pd‐4@CNFs catalyst, TiO2 with a mass fraction of 10% was added to produce Pd/TiO2@CNFs catalyst (Pd‐4/TiO2‐10@CNFs). The electrocatalytic activity of Pd‐4/TiO2‐10@CNFs increased to 3,850.4 A·g−1, which was 31.9 times higher than that of commercial Pd/C catalysts. These results demonstrated that the novel Pd/TiO2@CNFs catalyst is expected to be an efficient and durable catalyst for DMFC.

Efficient CO Oxidative Coupling to Dimethyl Oxalate over the Pd/Al2O3 Nanocatalyst with the Assistance of Co Doping

AbstractCO oxidative coupling to dimethyl oxalate (DMO) is an important approach for the product of ethylene glycol and CO elimination. In this work, the Co doped Pd/Al2O3 nanocatalyst was highly effective for CO oxidative coupling and enhanced remarkably CO conversion and the formation of DMO. The maximum DMO STY reached 1082 g L−1 h−1 over the Pd/Al2O3@1/20Co catalyst at 130 °C for 2 h under the space velocity of 3000 h−1, which is two times higher than that over the Pd/Al2O3 catalyst. The Co modification and its influence on the structure of the Pd/Al2O3 catalyst were also studied systematically by XRD, TEM, CO‐TPD, N2 physical adsorption and XPS techniques. An appropriate Co doing was confirmed to promote distinctly the generation of smaller Pd particles and the adjustment of the adsorption or activation of CO over the catalyst. A positive interaction between Pd nanoparticles and the modulated support with Co doping was demonstrated and favored the enhanced activity of the catalyst for the reaction.

The Pd/ZrO2 catalyst inversely loaded with various metal oxides for methanol synthesis from carbon dioxide

The selectivity and stability of catalysts for methanol synthesis from CO2 still remain to be enhanced. In this work, we synthesized a series of Pd/ZrO2 catalysts inversely loaded with various metal oxide promoters (ZnO, In2O3, and CeO2), those would partially cover Pd metal surface and form some new metal-promoter interface, to explore the nature in the performance of CO2 hydrogenation to methanol. The catalyst synthesized by this approach could limit the growth of Pd particles during the reduction and form new metal–metal oxide interfaces with different functions of CO2 hydrogenation, improving the reaction performance of Pd-ZrO2 catalysts. As a result, the ZnO-Pd/ZrO2 catalyst exhibited the highest CO2 conversion (12.0 %), methanol selectivity (95.6 %), and STY of methanol (472 gMeOHkgcat-1h−1), with excellent stability. The results of HRTEM, H2-TPR, XPS, and XAFS showed that the ZnO-Pd/ZrO2 catalyst had the typical Pd-ZnO interface with Pd2+ species after the H2 reduction, which could enhance the adsorption and activation of CO2. In addition, the in situ DRIFTS and NAP-XPS results implied that the Pd-ZnO interface significantly improved the formation of formate (HCOO*) and methoxy (H3CO*) species, which were considered to be the key intermediates of methanol generation, and thus greatly enhanced the selectivity of methanol.

Catalytic Hydroconversion of Lauric Acid Over Poly(N-vinyl-2-pyrrolidone)-Coated Pd Nanoparticles on ZIF-8

A subclass of Metal-Organic Frameworks, Zeolitic Imidazole Frameworks-8 (ZIF-8) is known as an emerging material that has the characteristic of a large surface area, good thermal stability as well as a high porosity. Instead of having extraordinary properties, ZIF-8 consists of Lewis acid and Lewis base site on its Zn metals and 2-methylimidazole which are the important components for the catalyst. In this study, Pd-Poly(N-vinyl-2-pyrrolidone) coated on ZIF-8 (Pd-PVP@ZIF-8) was synthesized by mixed Pd-PVP solution and ZIF-8 precursors at room temperature. The Pd-PVP solution was varied from 10 to 50 ml to differentiate the Pd concentration in ZIF-8. As-synthesized 50 ml of Pd-PVP on ZIF-8 (50Pd-PVP@ZIF-8) showed catalytic activity in the conversion of 98.6% lauric acid to produce 78.2% of 1-dodecanol at optimum condition 320 °C for 6 h. The synergy between Pd-PVP as metal and ZIF-8 as metal support as well as high dispersion of Pd particles could enhance performance in the conversion of lauric acid. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Effective Prevention of Palladium Metal Particles Sintering by Histidine Stabilization on Silica Catalyst Support

AbstractA robust method for enhancing the dispersion and stabilization of small metal nanoparticles in heterogeneous catalysts is developed. It involves in situ complexation of palladium(II) by histidine, in water, prior to impregnation in fumed silica. TEM images show that the histidine facilitates dispersion of the Pd(II) into finer nanoscale particles (≈2 nm) uniformly distributed on the support, rather than the large clusters (≈5 nm) seen in the absence of histidine. After hydrogen reduction, assessments using CO chemisorption and propylene hydrogenation indicate that the coordinated histidine might obscure the active sites on the Pd particles. However, as histidine decomposes between 220 and 300 °C in air, these materials are treated at 225 °C in air for 48 h. Afterwards the Pd(II) particles remain the same size, but after hydrogen reduction, there is a 2.4‐fold increase in CO gas adsorption, indicative of an expanded Pd surface area. Furthermore, superior catalyst stability (activity >200 h) is observed during propylene hydrogenation at 250 °C. This is consistent with histidine use having generated widely spaced, uniformly small, Pd nanoparticles on the silica support which is expected to help prevent agglomeration (sintering) during catalysis. This is a convenient low‐cost strategy for reducing metal content, preventing sintering and optimizing catalyst performance.

Highly Active and Stable Pd/MgAl2O4 Catalysts for Methane Catalytic Combustion

Mesoporous MgAl2O4 is synthesized via a novel sol–gel combustion method and the concentration of oxygen defects on the surface is modulated through varying the calcination temperature (850, 900, 1000, and 1100 °C). Notably, the 1Pd/MgAl2O4‐1000 catalyst exhibits superior catalytic activity and stability. The turnover frequency (TOF) for 1Pd/MgAl2O4‐1000 is 0.079 and 0.058 s−1 under dry conditions (300 °C) and wet conditions (380 °C), respectively. The results of H2 temperature‐programmed reduction and X‐Ray photoelectron spectroscopy reveal that the principal active species within the Pd/MgAl2O4‐y catalyst is PdO. Specifically, the Pd–MgAl2O4‐1000 catalyst exhibits the lowest temperature reduction peak (120 °C) and the highest redox capability. Additionally, O2 temperature‐programmed oxidation further elucidates that PdOx species in the Pd/MgAl2O4‐1000 catalyst is prone to decomposition and the resultant palladium metal is readily reoxidized. Consequently, the rapidity of the redox cycle between PdO and Pd0 emerges as a pivotal factor in CH4 catalytic combustion. Furthermore, a correlation analysis among catalyst particle size, oxygen defect concentration, and TOF is conducted. The findings illustrate a distinct volcano‐shaped curve in the relationship between oxygen defect concentration and TOF for the 1Pd/MgAl2O4−y catalysts. A comparable trend is also evident in the correlation between Pd particle size and TOF.

Degradation of bisphenol F by peroxymonosulfate activated with palladium-based catalysts

In this study, supported Pd catalysts were prepared and used as heterogeneous catalysts for the activation of peroxymonosulfate (PMS) which successfully degrade bisphenol F (BPF). Among the supported catalysts (i.e., Pd/SiO2, Pd/CeO2, Pd/TiO2 and Pd/Al2O3), Pd/TiO2 exhibited the highest catalytic activity due to the high isoelectric point and high Pd0 content. Pd/TiO2 prepared by the deposition method leads to high Pd dispersion, which are the key factors for efficient BPF degradation. The influencing factors were investigated during the reaction process and two possible degradation pathways were proposed. Density functional theory (DFT) calculations demonstrate that stronger BPF adsorption and BPF degradation with lower reaction barrier occurs on smaller Pd particles. The catalytic activities are strongly dependent on the structural features of the catalysts. Both experiments and theoretical calculations prove that the reaction is actuated by electron transfer rather than radicals.

Nanoscale intimacy in hierarchical catalytic structures for mediating furfural hydroconversion over Pd/CoxOy/SiAlOz

Precisely controlling nanoscale metal-acid intimacy of bifunctional catalysts is increasingly being exploited to improve the performance toward the tandem reactions. It remains a critical challenge to rationally design the spatial organization of dual-functional sites due to the lack of effective synthesis and material characterization methods at the nanoscale. Here we impose hierarchical structures into bifunctional catalysts, wherein Pd particles are controllably deposited on cobalt oxide (CoxOy) nanoglues, which themselves are dispersed on high-surface-area and acid silica-alumina (SiAlOz). The hydroconversion of furfural demonstrates that the catalytic performance is optimized by tailoring the intimacy between Pd and acid sites, that is, with an appropriate nanoscale rather than the closest intimacy. The conversion from furfural to cyclopentanone on hierarchical catalytic structures in Pd/CoxOy/SiAlOz undergoes the treble-site catalytic mechanism, comprising the dissociation of H2 on Pd, the preferential adsorption and hydrogenation of the carbonyl on CoxOy, followed by the hydrogenative ring-rearrangement of furfuryl alcohol intermediate on SiAlOz via the synergistic effect of acid sites and hydrogen spillover. Besides, the asynchronous catalysis resulting from Pd ensemble isolation from SiAlOz surface profoundly restrains the generation of tetrahydrofurfuryl alcohol by elongating the distance of hydrogen spillover, weakening the hydrogenation of the furan ring flat adsorbed on SiAlOz. Resultant Pd/CoxOy/SiAlOz-40 with an optimal Pd-acid intimacy delivers a conversion of 96% and selectivity toward cyclopentanone of 88%, outperforming most state-of-the-art noble metal catalysts. We anticipate that such a concept and synthesis strategy of hierarchical catalytic structures will extend the understanding of the metal-acid intimacy and provide a feasible approach for delicately regulating the location of functional sites in bifunctional catalysts, the results of which may enable the properties of multifunctional catalysts to be modulated to specific target processes.

Voltammetric quantification of H:Pd ratio complicated by α↔β phase transition in PdHx: Electrodes with low Pd loadings

The Pd hydride (PdHx) is a typical system to study the fundamentals of solute intercalation and phase transformations or to determine the effect of strain on the rate of electrocatalytic reactions. A crucial methodological aspect, however, involves quantitatively determining the hydrogen-to-palladium atomic ratio (H:Pd) under experimental conditions where various incidental contributions to the total electrode charge are comparable to the charge spent for H adsorption/absorption and desorption. This is the case for electrodes with relatively low (dozens of μg/cm2) loadings of Pd on various porous supports, typically used to study the oxidation of small organic molecules or the reduction of oxygen in acidic or alkaline fuel cells. Ultra-low Pd loadings (often in the range of a few μg/cm2) are also typical for Pd nanoparticles on smooth supports, which are commonly considered as model systems for in situ structural studies of hydrogen sorption. To determine accurately the H content in Pd particles, we propose a technique based on analysis of charge disbalance at anodic and cathodic scans of a cyclic voltammogram, and also address the contribution of adsorbed H. To illustrate the possibilities and limitations of this technique, we present the voltametric study of thin electrodeposited Pd layers on glassy carbon and of a carbon-supported Pd catalyst.

Effect of physicochemical properties of carbons on the performance of bead-type Pd/C catalysts for furfural hydrogenation

In green heterogeneous catalytic systems, alginate has emerged as a promising material for transforming powder catalysts into solid forms because of its sustainability and non-toxicity. Herein, the effect of carbon supports, including activated carbon (AC), carbon black (CB), carbon nanotubes (CNT), and carbon nanofibers (CNF), on a bead-type Pd/alginate-carbon catalyst was studied. Bead-type supports were synthesized by alginate gelation, and Pd-supported bead-type catalysts were prepared by a chemical reduction method. The catalytic activity in the hydrogenation of furfural was evaluated. Physical properties such as the specific surface area and pore volume of the carbon support greatly influenced the properties of the bead-type Pd/C catalyst. Pd/CB-alginate bead (AB), which had the highest specific surface area and pore volume, exhibited the smallest Pd particle size and dispersion, resulting in the highest catalytic performance. Additionally, the catalyst exhibited the highest FF conversion of 99 % and tetrahydrofurfuryl alcohol selectivity of 92 % under 20 bar of H2 at 35 ℃ for 4 h.

The performance and mechanism of HCHO oxidation on Pd/SiO2 catalysts with different Pd particle sizes

In general, for Pd-based catalysts, the smaller the Pd particles on the catalysts are, the better the activity for HCHO oxidation; this has solely been ascribed to the high Pd dispersion on the catalysts’ surface. However, the Pd site effect on HCHO oxidation is still not clear. In this work, we regulated the proportions of different Pd sites on Pd/SiO2 catalysts by high-temperature treatment of the carriers. With the increase in treatment temperature, the dominant active sites on Pd particles changed from terraces to steps and finally to corner sites. The corner sites were found to be important for oxygen activation, which led to the HCHO catalytic oxidation performance increasing in the order Pd/SiO2, Pd/SiO2(500) and Pd/SiO2(800). It is worth noting that in the reaction pathway for HCHO oxidation, formate was the primary intermediate on the Pd/SiO2 catalyst. However, in addition to formate, CO species were also detected on the Pd/SiO2(500) and Pd/SiO2(800) catalysts. DFT results confirmed that the corner sites were more favorable for the HCHO → CHO → CO pathway, compared to the terrace sites. This work elucidates the effect of Pd sites on the HCHO oxidation mechanism over Pd/SiO2 catalysts, providing valuable insights for the design of highly active catalysts.

Facile Transfer Hydrogenation of N-Heteroarenes and Nitroarenes Using Magnetically Recoverable Pd@SPIONs Catalyst.

Catalysts with active, selective, and reusable features are desirable for sustainable development. The present investigation involved the synthesis and characterization of bear-surfaced ultrasmall Pd particles (<1 nm) loaded onto the surface of magnetic nanoparticles (8-10 nm). The amount of Pd loading onto the surface of magnetite is recorded as 2.8 wt %. The characterization process covered the utilization of scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), transmission electron microscopy (TEM), inductively coupled plasma (ICP), and X-ray photoelectron spectroscopy (XPS) methods. The Pd@Fe3O4 catalyst has shown remarkable efficacy in the hydrogenation of quinoline, resulting in the production of >99% N-ring hydrogenated (py-THQ) product. Additionally, the catalyst facilitated the conversion of nitroarenes into their corresponding aniline derivatives, where hydrogen was achieved by H2O molecules with the aid of tetrahydroxydiboron (THDB) as an equilibrium supportive at 80 °C in 1 h. The high efficiency of a transfer hydrogenation catalyst is closely related to the metal-support synergistic effect. The broader scope of functional group tolerance is evaluated. The potential mechanism underlying the hydrogenation process has been elucidated through the utilization of isotopic labeling investigations. The application of the heterocyclic compound hydrogenation reaction is extended to formulate the medicinally important tubular polymerization inhibitor drug synthesis. The investigation of the recyclability of Pd@Fe3O4 has been conducted.