Photoelectron spectra of an Al70Pd21Mn9 quasicrystal and the cubic alloy Al60Pd25Mn15

Coupling Glycerol Conversion with Hydrogen Production Using Alloyed Electrocatalysts

Herein, uniform precious alloys including PtAg, PdAg, and PtPdAg nanoparticles were synthesized as electrocatalysts for glycerol oxidation reaction (GOR). The structures of the samples were characterized by transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectrometry. The catalytic performance of the samples was evaluated in both alkaline and acidic electrolytes. Among the samples, PtPdAg exhibited superior activity with the largest current density of 3.77 mA cm-2 in alkaline solutions, which is 4.1 and 7.7 times those of Pd/C and Pt/C, respectively. In acidic solutions, the PtPdAg catalyst shows the highest current density of 0.58 mA cm-2, which is 1.8 times that of the Pt/C catalyst. The products of GOR were analyzed by high-performance liquid chromatography. Eight products including oxalic acid, tartronic acid, glyoxylic acid, glyceric acid, glyceraldehyde (GLAD), glycolic acid, lactic acid, and dihydroxyacetone were detected. Notably, in acidic solutions, PtAg and PtPdAg yielded the largest GLAD selectivity of 92.2% at 0.6 and 0.8 V, respectively. Using the alloyed catalysts, electrolysis processes coupling the GOR with the hydrogen evolution reaction were conducted. The conversion of glycerol and production of hydrogen were determined. To highlight the energy efficiency, a solar-panel-powered electrolysis process was conducted for the simultaneous production of hydrogen and high-valued products.

Palladium nanoparticle based smart hydrogels for NIR light-triggered photothermal/photodynamic therapy and drug release with wound healing capability

Tumor recurrence and wound repair are two major challenges following cancer surgical resection that can be addressed through precision nanomedicine. Herein, palladium nanoparticles (Pd NPs) with photothermal and photodynamic therapy (PTT/PDT) capacity were successfully synthesized. The Pd NPs were loaded with chemotherapeutic doxorubicin (DOX) to form hydrogels (Pd/DOX@hydrogel) as a smart anti-tumor platform. The hydrogels were composed of clinically approved agarose and chitosan, with excellent biocompatibility and wound healing ability. Pd/DOX@hydrogel can be used for both PTT and PDT with a synergistic effect to kill tumor cells. Additionally, the photothermal effect of Pd/DOX@hydrogel allowed the photo-triggered drug release of DOX. Therefore, Pd/DOX@hydrogel can be used for near-infrared (NIR)-triggered PTT and PDT as well as for photo-induced chemotherapy, efficiently inhibiting tumor growth. Furthermore, Pd/DOX@hydrogel can be used as a temporary biomimetic skin to block the invasion of foreign harmful substances, promote angiogenesis, and accelerate wound repair and new skin formation. Thus, the as-prepared smart Pd/DOX@hydrogel is expected to provide a feasible therapeutic solution following tumor resection.

Effective catalytic hydrodechlorination removal of chloroanisole odorants in water using palladium catalyst confined in zeolite Y

Chloroanisoles is a class of odorous pollutants commonly identified in drinking water. In the present study, we confined noble metal palladium (Pd) in the micropores of zeolite Y (ie-Pd@Y) using an ion exchange method, and applied it for the catalytic hydrodechlorination removal of chloroanisoles (represented by 2,4,6-trichloroanisole/TCA) in water. Pd supported on zeolite Y surface (im-Pd/Y, prepared by conventional impregnation method) was used as the benchmarking catalyst. The characterization results revealed that ie-Pd@Y had smaller Pd particle size and higher Pdⁿ⁺/Pd⁰ ratio than im-Pd/Y. The catalytic hydrodechlorination of TCA followed a concerted dechlorination pathway and the Langmuir-Hinshelwood model. The ie-Pd@Y catalysts with different Pd loadings exhibit excellent catalytic activities with more than 95% of TCA removed within 30 min, which is far superior to the im-Pd/Y catalysts (27-70%). Moreover, due to the confinement effect of zeolite Y, ie-Pd@Y displayed enhanced catalytic stability as compared with im-Pd/Y. The initial activity of ie-Pd@Y was more than 20 times higher than that of im-Pd/Y after five reaction cycles. Additionally, with the assistance of sieving effect, ie-Pd@Y displayed much stronger capability against the interference from dissolved organic matter than im-Pd/Y. The present results demonstrate that the confined catalysts ie-Pd@Y can be applied in liquid phase catalytic hydrogenation to effectively eliminate halogenated odorants in waters.

Magnetically separable nickel ferrite supported palladium nanoparticles: Highly reusable catalyst in Sonogashira cross-coupling reaction

There is an increasing attention in developing highly efficient and reusable palladium-based catalysts used for the coupling reactions due to the high cost of palladium metal salts. Magnetically separable palladium nanoparticles have a high potential to be used as catalysts in numerous organic reactions due to their facile separation from the reaction medium by an external magnet. Herein, NiFe₂O₄ supported palladium nanoparticles (Pd/NiFe₂O₄) were successfully prepared by impregnation and reduction method in water and used as catalysts for Sonogashira cross-coupling reactions. Magnetically separable Pd/NiFe₂O₄ catalysts were found to be highly active and reusable in this reaction. Pd/NiFe₂O₄ provided an outstanding turnover frequency value (106.4 h^-1) in the reaction between phenylacetylene and iodobenzene in ethanol at 70 °C and it was also found to be highly active in the water. Magnetically separable Pd/NiFe₂O₄ exhibited high catalytic performance even after the tenth use in this reaction.

Effect of Counterbody on Friction and Wear Properties of Copper-MgP-Graphite Composites Prepared by Powder Metallurgy

The purpose of this study was to investigate the influence of different counterbodies against Cu/magnesium phosphate treated graphite (Cu-MgPG) composite materials to find the best material combination in terms of friction coefficient and specific wear amount. A Cu matrix composite reinforced with 10 vol% magnesium phosphate treated graphite and pure Cu powder were prepared by powder metallurgy techniques under the same consolidation processing condition. The friction and wear properties of the composites were investigated at 10 N using a pin-on-disc tribometer on Al2O3, SiC and SUJ2 bearing steel counterbodies. The Cu-MgPG/Al2O3 pair showed the lowest friction coefficient, but the specific wear rate tended to increase slightly when compared with Cu/Al2O3 pair. On the other hands, the Cu-MgPG/SUJ2 pair showed about the same specific wear rate as the Cu/SUJ2 pair, but the friction coefficient was significantly reduced. These phenomena are thought to be due to the fact that the added graphite acts as a solid lubricant during sliding and also suppresses the oxidation behavior of the sliding material.

Iron nanoparticles to recover a co-contaminated soil with Cr and PCBs

Little attention has been given to the development of remediation strategies for soils polluted with mixture of pollution (metal(loid)s and organic compounds). The present study evaluates the effectiveness of different types of commercial iron nanoparticles (nanoscale zero valent iron (nZVI), bimetallic nZVI-Pd, and nano-magnetite (nFe₃O₄)), for the remediation of an industrial soil co-contaminated with Cr and PCBs. Soil samples were mixed with nZVI, nZVI-Pd, or nFe₃O₄ at doses selected according to their reactivity with PCBs, homogenized, saturated with water and incubated at controlled conditions for 15, 45 and 70 days. For each sampling time, PCBs and chromium were analyzed in aqueous and soil fractions. Cr(VI) and Cr leachability (TCLP test) were determined in the soil samples. The treatment with the three types of iron nanoparticles showed significant reduction in Cr concentration in aqueous extracts at the three sampling times (> 98%), compared to the control samples. The leachability of Cr in treated soil samples also decreased and was stable throughout the experiment. Results suggested that nZVI and nZVI-Pd immobilized Cr through adsorption of Cr(VI) on the shell and reduction to Cr(III). The mechanism of interaction of nFe₃O₄ and Cr(VI) included adsorption and reduction although its reducing character was lower than those of ZVI nanoparticles. PCBs significantly decreased in soil samples (up to 68%), after 15 days of treatment with the three types of nanoparticles. However, nFe₃O₄ evidenced reversible adsorption of PCBs after 45 days. In general, nZVI-Pd reduced PCB concentration in soil faster than nZVI. Control soils showed a similar reduction in PCBs concentration as those obtained with nZVI and nZVI-Pd after a longer time (45 days). This is likely due to natural bioremediation, although it was not effective for Cr remediation. Results suggest that the addition of nZVI or nZVI-Pd and pseudo-anaerobic conditions could be used for the recovery of soil co-contaminated with Cr and PCBs.

Characterization of buried interfaces using Ga Kα hard X-ray photoelectron spectroscopy (HAXPES)

HAXPES enables the detection of buried interfaces with an increased photo electron sampling depth.

Constructing epitaxially grown heterointerface of metal nanoparticles and manganese dioxide anode for high-capacity and high-rate lithium-ion batteries

Low ion migration rate and irreversible change in the valence state in transition-metal oxides limit their application as anode materials in Li-ion batteries (LIBs). Interfacial optimization by loading metal particles on semiconductor can change the band structure and thus tune the inherent electrical nature of transition-metal oxide anode materials for energy applications. In this work, Au nanoparticles are epitaxially grown on MnO₂ nanoroads (MnO₂-Au). Interestingly, the MnO₂-Au anode shows excellent electrochemical activity. It delivers high reversible capacity (about 2-3 fold compared to MnO₂) and high rate capability (740 mA h g^-1 at 1 A g^-1). The electron holography and density functional theory (DFT) results demonstrate that the Au particles on the surface of MnO₂ can form a negative charge accumulation area, which not only improves the Li ion migration rate but also catalyzes the transition of MnO_x to Mn⁰. This study provides a direction to heterointerface fabrication for transition-metal oxide anode materials with desired properties for high-performance LIBs and future energy applications.

Nickel−palladium alloy nanoparticles supported on reduced graphene oxide decorated with metallic aluminum nanoparticles (Al-rGO/NiPd): a multifunctional catalyst for the transfer hydrogenation of nitroarenes and olefins using water as a hydrogen source

A multifunctional nanocatalyst, Al-rGO/Ni₄₀Pd₆₀, is designed for the transfer hydrogenation of nitroarenes and olefins using water as a hydrogen source and solvent.

Directing nitrogen-doped carbon support chemistry for improved aqueous phase hydrogenation catalysis

Influencing stability and performance through directing nitrogen-doping in carbon support materials.

Electrochemical and adsorption behaviors of thiadiazole derivatives on the aluminum surface

The electrochemical and adsorption behaviors of BODTA were studied in a 3.0 wt% NaCl solution via different electrochemical methods. Different concentrations of 2,5-bis(octyldithio)-1,3,4-thiadiazole (BODTA) were dissolved in rolling oil, and then aluminum electrodes coated with rolling oil were applied as the working electrode. The morphology and the elements of the electrode surface were studied via SEM, EDS and XPS. Results showed that BODTA had a slight inhibition efficiency of 10.75% when its concentration was 0.1 wt%; however, with the changes in the BODTA concentration from 0.3 wt%, 0.5 wt% to 0.7 wt%, BODTA had an antagonistic effect on the aluminum surface and accelerated the corrosion. The corresponding inhibition efficiencies became negative, which were −21.53%, −30.34%, and −18.82%. The analysis of elements and chemical states on the surface indicated that Al–N and Al–S bonds were formed between aluminum and BODTA. Furthermore, quantum chemical calculations were also performed, which manifested that N and S atoms were the main reactive sites. S atoms on side chains had a stronger reactivity than those in the thiadiazole ring. Finally, the present study was helpful to understand the electrochemical and adsorption behaviors of BODTA on aluminum, and made contributions to the application of BODTA in rolling oil.

Electrochemical and adsorption behaviors of thiadiazole derivatives on the aluminum surface were investigated by an experimental and quantum chemical approach.

Double-zigzag boron chain-enhanced Vickers hardness and manganese bilayers-induced high d-electron mobility in Mn3B4

The D7b-type structure Mn3B4 was fabricated by high-temperature and high-pressure (HPHT) methods. Hardness examination yielded an asymptotic Vickers hardness of 16.3 GPa, which is much higher than that of Mn2B and MnB2. First principle calculations and XPS results demonstrated that double zigzag boron chains form a strong covalent skeletons, which enhances this structure's integrity with high hardness. Considering that the hardensses of MnB and Mn3B4 are higher than those of Mn2B and MnB2, zigzag and double zigzag boron backbones are superior to isolated boron and graphite-like boron layer backbones for achieving higher hardness. This situation also states that a higher boron content is not the sole factor for the higher hardness in the low boron content transition metal borides. Futhermore, the co-presence of metallic manganese bilayers contribute to the high d-electron mobility and generate electrical conductivity and antiferromagnetism in Mn3B4 which provide us with a new structure prototype to design general-purpose high hardness materials.

Tetramer Compound of Manganese Ions with Mixed Valence [MnII MnIII MnIV] and Its Spatial, Electronic, Magnetic, and Theoretical Studies

Using different spectroscopic techniques and computational calculations, we describe the structural and electromagnetic relationship that causes many interesting phenomena within a novel coordination compound with mixed valence manganese (II, III and IV) in its crystal and powder state. The novel compound [MnII MnIII MnIV(HL)2(H2L)2(H2O)4](NO3)2(H2O) 1 was obtained with the Schiff base (E)-2-((2-hydroxybenzylidene)amine)-2-(hydroximethyl)propane-1,3-diol, (H4L), and Mn(NO3)2.4H2O. The coordination reaction was promoted by the deprotonation of the ligand by the soft base triethylamine. The paper’s main contribution is the integration of the experimental and computational studies to explain the interesting magnetic behavior that the mixed valence manganese multimetallic core shows. The results presented herein, which are rarely found for Mn(II), (III) and (IV) complexes, will contribute to the understanding of the magnetic communication generated by the valence electrons and its repercussion in the local geometry and in the overall crystalline structure.

One-pot synthesis of Pd@Pt3Ni core–shell nanobranches with ultrathin Pt3Ni{111} skins for efficient ethanol electrooxidation

Pd@Pt₃Ni core–shell nanobranches with ultrathin Pt₃Ni{111} skins were facilely synthesized in one-pot and exhibited outstanding performances for ethanol electrooxidation.

Metal vapor synthesis of ultrasmall Pd nanoparticles functionalized with N-heterocyclic carbenes

The synthesis of N-heterocyclic carbene (NHC)-stabilized palladium nanoparticles (PdNPs) by an entirely new strategy comprising the NHC functionalization of ligand-free PdNPs obtained by metal vapor synthesis is described.

Manganese mono-boride, an inexpensive room temperature ferromagnetic hard material

We synthesized orthorhombic FeB-type MnB (space group: Pnma) with high pressure and high temperature method. MnB is a promising soft magnetic material, which is ferromagnetic with Curie temperature as high as 546.3 K, and high magnetization value up to 155.5 emu/g, and comparatively low coercive field. The strong room temperature ferromagnetic properties stem from the positive exchange-correlation between manganese atoms and the large number of unpaired Mn 3d electrons. The asymptotic Vickers hardness (AVH) is 15.7 GPa which is far higher than that of traditional ferromagnetic materials. The high hardness is ascribed to the zigzag boron chains running through manganese lattice, as unraveled by X-ray photoelectron spectroscopy result and first principle calculations. This exploration opens a new class of materials with the integration of superior mechanical properties, lower cost, electrical conductivity, and fantastic soft magnetic properties which will be significant for scientific research and industrial application as advanced structural and functional materials.

Mn-containing titanium surface with favorable osteogenic and antimicrobial functions synthesized by PIII&D

Reasonable incorporation of manganese into titanium is believed to be able to enhance the osteogenic and antibacterial activities of orthopedic implants. However, it is still a challenge to compromise Mn-induced cytotoxicity and better develop its biocompatibility and antimicrobial ability. To pinpoint this issue, a stable Mn ion release platform was created on Ti using plasma immersion ion implantation and deposition (PIII&D) technique. Compared with as-etched titanium, as a result, promoted antibacterial abilities against gram-negative bacteria species and enhanced osteogenic-related gene expressions on rBMMSC were observed on Mn-containing sample. Meanwhile, the Mn-containing samples showed no obvious cytotoxicity. Our results here provide insight to be better understanding the relationships between additives-induced biological performance and the dose, state, and stability of the doped element.

Significance of the electron-density of molecular fragments on the properties of manganese(iii) β-diketonato complexes: an XPS and DFT study

The group electronegativity of the R-groups of the ligand influences the XPS binding energies and the amount of charge transferred in the Mn 2p_3/2 photoelectron lines. DFT studies illustrated different Jahn–Teller elongation bond stretch isomers.

One-pot synthesis of Hantzsch dihydropyridines using a highly efficient and stable PdRuNi@GO catalyst

The method for the synthesis of 1,4-dihydropyridine compounds in the presence of Pd–Ni–Ru@GO was developed, which is simple, effective and productive.

Palladium–gold catalyst for the electrochemical reduction of CO2 to C1–C5 hydrocarbons

Electrochemical reduction of CO₂ on PdAu electrodes yields the production of C₁–C₅ hydrocarbons.

Preparing highly-dispersed noble metal supported mesoporous silica catalysts by reductive amphiphilic molecules

We present an in situ reduction strategy to prepare mesoporous silica supported by highly-dispersed noble metals.

Palladium(0) nanoparticles supported on polydopamine coated Fe3O4 as magnetically isolable, highly active and reusable catalysts for hydrolytic dehydrogenation of ammonia borane

Palladium(0) nanoparticles supported on polydopamine coated magnetic ferrite nanopowders are highly active and reusable catalyst in hydrogen generation from the hydrolysis of ammonia borane with a turnover frequency of 14.5 min⁻¹ at 25.0 ± 0.1 °C.

A nanostructured CeO2 promoted Pd/α-alumina diethyl oxalate catalyst with high activity and stability

A Pd–CeO₂/α-Al₂O₃ nanocatalyst was used as a catalyst for CO oxidative coupling to diethyl oxalate with the CO conversion significantly increased.

Room Temperature Ferromagnetic Mn:Ge(001)

We report the synthesis of a room temperature ferromagnetic Mn-Ge system obtained by simple deposition of manganese on Ge(001), heated at relatively high temperature (starting with 250 °C). The samples were characterized by low energy electron diffraction (LEED), scanning tunneling microscopy (STM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), superconducting quantum interference device (SQUID), and magneto-optical Kerr effect (MOKE). Samples deposited at relatively elevated temperature (350 °C) exhibited the formation of ~5–8 nm diameter Mn₅Ge₃ and Mn₁₁Ge₈ agglomerates by HRTEM, while XPS identified at least two Mn-containing phases: the agglomerates, together with a Ge-rich MnGe_~2.5 phase, or manganese diluted into the Ge(001) crystal. LEED revealed the persistence of long range order after a relatively high amount of Mn (100 nm) deposited on the single crystal substrate. STM probed the existence of dimer rows on the surface, slightly elongated as compared with Ge–Ge dimers on Ge(001). The films exhibited a clear ferromagnetism at room temperature, opening the possibility of forming a magnetic phase behind a nearly ideally terminated Ge surface, which could find applications in integration of magnetic functionalities on semiconductor bases. SQUID probed the co-existence of a superparamagnetic phase, with one phase which may be attributed to a diluted magnetic semiconductor. The hypothesis that the room temperature ferromagnetic phase might be the one with manganese diluted into the Ge crystal is formulated and discussed.