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Highlights • Bimetallic catalysts Pd-Ru and Pt-Ru supported on FAU and γ-Al 2 O 3 were synthesized. • Two crystallographic phases coexisting in the synthesized zeolite (LTA and FAU). • The phase FAU prevailing when the material was calcinated at 550 °C. • The formation of the Pd-Ru alloy phase was confirmed by XPS and HRTEM. • Pd-Ru was more selective metal combination to added-value furan derivatives. • Pd-Ru/FAU lost less metal after its first use than Pd-Ru/ γ-Al 2 O 3. • Re-used Pd-Ru/FAU was more selective to furan derivatives and less to byproducts. Abstract It is well known the effects and limitations of the use of fossil fuels, for that reason is necessary to establish alternative sources of energy. The 5-hydroxymethylfurfural (HMF) is a chemical compound that can be obtained from the carbohydrates present in the biomass. Is a key compound for the obtaining of several valuable chemicals, many of them have a promising application as biofuels. In the present work, Pd-Ru and Pt-Ru bimetallic catalysts with low metal content (0.5%) supported on commercial γ-Al 2 O 3 and FAU zeolite prepared by hydrothermal method, were synthesized and characterized to transform HMF into valuable chemicals under mild reaction conditions. Two crystallographic phases were found to coexist in the zeolite synthesized as support, the FAU phase prevailing over the LTA when calcined at 550 °C. The system studied with formic acid as hydrogen donor, under mild reaction conditions, showed a partial hydrogenation of HMF molecule evidenced in the 5-MF and 2,5-DMF formation. Also, a partial oxidation and esterification is happening for the formation of 2,5-DFF and 5-A-2-F, respectively. The catalysts supported on FAU showed better conversion of HMF that catalysts supported on γ-Al 2 O 3. Although all metals showed catalytic activity by separed, Pd-Ru combination was more selective to produce 5-MF, 2,5-DMF and 2,5-DFF than Pt-Ru combination, and showed production of valuable furan derivatives even in their second and thir use. Pd–Ru/FAU catalyst formed a PdRu alloy phase, which can be related to its better catalytic performance. [ABSTRACT FROM AUTHOR]

In this study, a magnetic Fe@Ag bimetallic catalyst was synthesized via a facile one-pot method in the presence of excessive sodium borohydride (NaBH4). The as-synthesized Fe@Ag bimetal was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometer (VSM). The influences of Fe/Ag molar ratio and gum arabic (GA) on the catalytic activity of Fe@Ag bimetal were investigated. It was found that the FeAg3-0.14 wt% bimetal with Fe/Ag molar ratio of 1:3 and GA concentration of 0.14 wt% exhibited the best activity for catalytic reduction of 4-NP, giving a pseudo-first-order rate constant of 48.8 min–1g–1. The saturation magnetization (MS) of FeAg3-0.14 wt% was 5.6 emu/g, which ensured the catalyst could be easily separated and recycled using a magnet. Moreover, the catalytic activity and phase composition of FeAg3-0.14 wt% showed no obvious changes after five continuous runs, indicating its high stability and reusability. Ag shell coated on the surface of Fe core played a main role in the catalytic reduction of 4-NP and also inhibited the oxidation of Fe core, which can be illustrated by electrochemical potentials and heterogeneous nucleation during the synthetic process. Furthermore, the Langmuir-Hinshelwood (L-H) model was applied to explain the catalytic mechanism of Fe@Ag bimetal. [ABSTRACT FROM AUTHOR]

Abstract: A combination of two green chemistry methods—fluid (supercritical carbon dioxide) and metal vapor synthesis—has afforded γ-Al2O3-based systems modified with Au, Pt, Au-Pt, and Pt-Au nanoparticles. It has been shown that bimetallic nanocomposites in the CO oxidation reaction are more efficient catalysts than monometallic systems. The composition of the Au-Pt/Al2O3 intermetallic compound and its evolution in the course of catalysis have been studied by X-ray photoelectron spectroscopy. It has been demonstrated that the increase in system activity during catalysis is accompanied by a significant rearrangement of the structure and composition of the nanocomposite surface. [ABSTRACT FROM AUTHOR]

Hexavalent chromium is one of the most chronic and harmful to human beings, animals, and environmental well-being, and hence needs a high attention to detoxify it. For this purpose, bimetallic (In,Ga) 2 (O,S) 3 oxy-sulfide nanoflower catalyst with different Ga contents was successfully synthesized at a low temperature of 150 °C via a facile method. It was systematically characterized and the visible light-driven photocatalytic reduction of toxic Cr(VI) was 100% completed at 4 min. The Cr(VI) reduction reaction rate constant was 13.8 fold higher than that of Ga-free In 2 (O,S) 3 catalyst. It also showed lower recombination of photogenerated charge carriers, faster interfacial reaction rate, and higher electrical conductivity. The photoexcited electrons and H + ions played crucial roles in the reduction of Cr(VI). The Cr(III) composition was 12.0% of the total atomic composition. The as-synthesized catalyst showed a tremendously fast Cr(VI) reduction activity and hence, it is promising for detoxification of hazardous Cr(VI). [ABSTRACT FROM AUTHOR]

Energy storage is needed in order to sustain the energy system on renewable energies like wind and solar power. Power-to-Gas (PtG) is a technology that enables the storage of the renewable electricity in a chemical carrier such as hydrogen, via water electrolysis, or methane, via carbon dioxide methanation. In this work a series of catalysts based on nickel and alumina, the catalyst commonly employed for carbon dioxide methanation, have been synthesised employing different calcination temperatures to study the influence of this parameter in the activity of the catalysts. As a result of this study 673 K was determined as the most suitable Moreover, the catalysts have also been tested at different pressures to determine the most suitable operating pressure. Although due to Le Chatelier's Principle a higher pressure results in an increasing yield, the study carried out proved that 10 bar is the most suitable pressure as the difference in the yield when increasing the pressure it is not high enough taking into account the costs and risks associated with higher pressures. [ABSTRACT FROM AUTHOR]

Abstract: Supported bimetallic catalysts have been studied because of their enhanced catalytic properties due to metal‐metal interactions compared with monometallic catalysts. We focused on galvanic deposition (GD) as a bimetallization method, which achieves well‐defined metal‐metal interfaces by exchanging heterogeneous metals with different ionisation tendencies. We have developed Ni@Ag/SiO2 catalysts for CO oxidation, Co@Ru/Al2O3 catalysts for automotive three‐way reactions and Pd−Co/Al2O3 catalysts for methane combustion by using the GD method. In all cases, the catalysts prepared by the GD method showed higher catalytic activity than the corresponding monometallic and bimetallic catalysts prepared by the conventional co‐impregnation method. The GD method provides contact between noble and base metals to improve the electronic state, surface structure and reducibility of noble metals. [ABSTRACT FROM AUTHOR]

Although noble metals were used as dopants, the synthesized composite is an economically and environmentally friendly photocatalyst, based on very low concentrations (Au-1 wt% and Ag-5 wt%) of both metals and its reusability in degradation experiments. The bimetallic photocatalyst was characterized by different techniques. Photocatalytic activity of Ag loaded Au/ZnO was evaluated by irradiating the sample solution under solar light and taking Acid Red 18 (AR 18) as an organic dye. The photocatalytic trials confirmed that the Ag-Au/ZnO composite exhibited improved photocatalytic efficiency compared with Ag-ZnO, Au-ZnO, commercial ZnO, bare ZnO, TiO 2 -P25 and TiO 2 (Aldrich) at pH 11 for the mineralization of Acid Red 18 dye. The effects of operational parameters such as the amount of photocatalyst, dye concentration, initial pH on photomineralization of AR 18 dye have been analyzed. Degradation intermediates were analyzed by GC–MS, and a degradation pathway was proposed. A mechanism is proposed for the degradation of AR 18 under solar light. Moreover, the Ag-Au/ZnO sample showed excellent stability after four photodegradation cycling runs. The antifungal activity of the prepared materials was tested against Aspergillus flavus , Aspergillus niger , Penicillim chryogenum , Trigoderma veride and Fusarium oxysporum and their antibacterial activity was tested against Bacillus subtilis , Escherichia coli , Pseudomonas aeruginosa , Staphylococcus aureus , streptococcus pyogenes. All doped ZnOs have moderate to good activity compared with bare ZnO. [ABSTRACT FROM AUTHOR]

The Fe–Co bimetallic catalyst supported on CaCO 3 was prepared by a wet impregnation method. The interactive effects among the key synthesis parameters such as drying time, calcination temperature, stirring speed, mass of CaCO 3 support on the yield and quality properties of the catalyst were investigated using 2 4 Factorial design of experiment. Additionally, the catalyst obtained under the optimal conditions was used to prepare Multi-walled carbon nanotubes (MWCNT) via chemical vapour deposition (CVD) of acetylene gas in a tubular horizontal reactor. The quality of the prepared materials was examined for their morphology, microstructure, elemental composition, surface chemical properties, thermal stability, surface area, and mineralogical phase by HRSEM, HRTEM, EDS, TGA, FTIR, BET and XRD. The results revealed that maximum catalyst yield of 99.6% obtained at the drying time of 12 h, calcination temperature of 100 °C, stirring speed of 1000 rpm and mass of CaCO 3 support of 10 g favoured the formation of MWCNT at 700 °C and 60 min reaction time. The results of statistical analysis demonstrated a direct relationship and synergetic effect between stirring speed and mass of support and the two factors exerted highest impact on the yield of catalyst than other parameters. Microscopy analysis revealed successful dispersion of Fe and Co particles onto CaCO 3 support while XRD patterns confirmed the presence of highly active crystalline mixed oxide (CoFe 2 O 4 ) as the dominant phase. The HRSEM/XRD analysis displayed the formation of tubular networks of graphitic carbon materials with few traces of by-products. The study established the absorption and not diffusion mechanism of Fe and Co onto CaCO 3 in the reaction sequence produced CoFe 2 O 4 during the wet impregnation process employed for catalyst preparation. [ABSTRACT FROM AUTHOR]

This work, for the first time, reports the synthesis, characterization, and catalytic properties of a novel type of bimetallic nanocrystals--Pd-Ru nanocrystals with a highly porous structure on the surface. The synthesis relies on a seed-mediated growth, at which Ru atoms are added to the surface of preformed Pd nanocubes as the seeds. The key to the successful synthesis is to direct the crystal growth along a 3D island mode through kinetic control. The Ru shells on Pd surfaces primarily take a hexagonal close packing (hcp) crystal structure. The extent of porosity for Ru shells can be conveniently controlled by adjusting the amount of Ru precursor introduced to a synthesis. The Pd-Ru porous nanocrystals exhibit a substantially enhanced peroxidaselike activity with a catalytic constant (Kcat) as high as 4.8 × 105 s-1, which is two-orders-of-magnitude greater than the Kcat value of natural peroxidases. [ABSTRACT FROM AUTHOR]

Homogeneously dispersed Au-Ag alloyed nanostructures varying from spherical (6–8 nm) to rod shape (aspect ratio ∼15–20 nm) were synthesized within the channels of amine modified mesoporous SBA-15 using post modification. Formation of alloy nanostructures for varying Au-Ag loadings have been supported by XPS and elemental mapping studies. Furthermore, changes in the surface/electronic properties of mesocomposites as a function of increased bimetallic Au:Ag loading have been elucidated with the help of XRD, BET, TEM and XPS studies respectively. It was found that synergism owing to electronic interplay between Au and Ag species concurrently improved the catalytic activity of bimetallic nanocomposites. Among the various monometallic and bimetallic mesocomposites, Au-Ag (5:1)/ m -SBA-15 nanocomposites exhibited the best catalytic activity (k = 2.12 × 10 −2 min −1 and 3.99 × 10 −2  min −1 ) for the selective reduction of nitrobenzene to aniline and p -nitroacetophenone to p -aminoacetophenone respectively. [ABSTRACT FROM AUTHOR]

Undoped NiO, W-doped NiO and Pd-doped NiO nanoflowers were prepared by hydrothermal, or precipitation method using NiSO 4 , WCl 6 and PdCl 2 as precursor compounds. The characterizations and microstructural analyses were performed by powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FESEM), and energy dispersive X-ray analysis (EDAX). Thin films of these materials were prepared and the gas adsorption properties of the prepared thin films were investigated towards o-xylene vapor. The influence of doping on o-xylene adsorption was studied. To this intent, thin films were deposited by dip-coating on quartz substrates and fixed onto the end of an optical fiber. This device worked in reflection mode, and transduction took place in the light that traveled through the core of the fiber. W-doped NiO exhibited superior performance to o-xylene compared to the other two samples. The response time, sensitivity and recovery time for undoped NiO, W-doped NiO and Pd-doped NiO thin films towards o-xylene were found as (∼50 s, 0.08 and ∼5 min), (∼35 s, 0.19 and ∼1 min), and (∼20 s, 0.10 and ∼3 min), respectively. Other volatile organic compounds such as benzene, toluene, ethanol, methanol and acetone vapors were also tested by W-doped NiO and the sensitivity order was o-xylene > toluene > benzene > acetone > ethanol > methanol. [ABSTRACT FROM AUTHOR]

Present investigation deals with the treatment of deactivated Co-Mn bromide catalyst for the recovery of Co and Mn as Co metal powder and chemical manganese dioxide by an integrated process comprising of a selective metal ion transfer from an aqueous solution containing a mixture of metal ions with a saponified solution of di-2ethyl-hexyl phosphoric acid, followed by selective scrubbing and metal stripping. The pure metal solutions so obtained were subjected to precipitation and hydrothermal treatment to obtain a desired material. The deactivated catalyst was leached by H 2 SO 4 in presence of H 2 O 2 followed by removing Fe, Si etc. The purified leach liquor of composition: 6.9 g/L Co, 9.4 g/L Mn was used for detail study to optimize the best conditions for the separation of Co from Mn. Experimental observations show that the extraction of both increased with increasing equilibrium pH and the concentration of the organic, with a separation factor of about 10, at equilibrium pH of 3. A quantitative extraction of Mn was possible with 20% D2EHPA in three stage counter-current extraction. After Co scrubbing, Mn was stripped with dilute H 2 SO 4 and high pure spherical shaped CMD was produced. Co in the raffinate was recovered as powder by hydrothermal H 2 - reduction. [ABSTRACT FROM AUTHOR]

As a typical congener of Polybrominated diphenyl ethers (PBDEs), 2,2′,4,4′-tetrabromodiphenyl ether (BDE47) has attracted more and more attention due to its high biological toxicity and environmental abundance. In this study, a novel polyanionic cellulose stabilized Pd/Fe (PAC-Pd/Fe) nanoparticle was successfully synthesized for BDE47 degradation under ambient condition. Batch experiments showed that BDE47 degradation followed pseudo first-order kinetic model. Pd loading played a crucial role as it affected the formation of activated hydrogen species H ∗ and accelerated electron transfer. At Pd loading of 0.3 wt%, nearly 100% BDE47 was degraded completely within 10 min by 0.4 g L −1 PAC-Pd/Fe nanoparticles. When compared with strong acidic (pH 3) and alkaline (pH 9 and 11) conditions, weak acidic condition (pH 5) was more favorable for BDE47 degradation, with nearly 100% BDE47 was removed within 7.5 min. In the presence of HA inhibited the degradation of BDE47, and the degradation efficiencies within 15 min decreased from 100%, 88.6%, 79.5% to 73.1% as HA concentration increased from 0, 10, 40 to 70 mg L −1 . The degradation of BDE47 by PAC-Pd/Fe nanoparticles was a reductive debromination process, and a stepwise debromination from n-Br to (n-1)-Br BDEs was the dominant reaction, in which the para -Br was more susceptible to remove than ortho -Br. This study suggests PAC-Pd/Fe nanoparticle can be utilized as a promising remediation technology for PBDEs contaminated wastewater. [ABSTRACT FROM AUTHOR]

Here, we reported on a route to the facile synthesis of bimetallic silver doped copper nanoparticles (Ag-Cu NPs) by AgNO 3 and CuSO 4 in the presence of sodium borohydride and sodium citrate. The present work described the preparation of the Ag-Cu NPs with sodium citrate and the use of them in colorimetric detection of mercury (II) ions. Ag-Cu NPs with an average diameter of 9.0 ± 0.8 nm were prepared via two step reduction at room temperature. The Ag-Cu NPs were thoroughly characterized by using UV–vis spectroscopy and transmission electron microscopy (TEM) techniques. The morphology and constitution of the Ag-Cu NPs were characterized by TEM, and the valence state of Ag-Cu NPs was confirmed by the X-ray photoelectron spectroscopic (XPS) result. The synthesized Ag-Cu NPs were yellow in color due to the intense surface plasmon absorption band centered at 406 nm. This high selective sensor allowed a direct quantitative assay of mercury ions (Hg 2+ ) with a detection limited of 0.51 nM. The synthesized Ag-Cu NPs also exhibited good catalytic activity in two model reactions, the reduction of the nitrophenols and potassium ferricyanide (III) by sodium borohydride. [ABSTRACT FROM AUTHOR]

Labor-saving preparation of highly active electrocatalysts for electrochemical energy conversion is extremely critical to the development of portable electronic devices. In this work, a hybrid catalyst of porous bimetallic PdCu nanofinger supported on graphene was simply synthesized by a one-step stabilizer-free method. The described method, carried out under room temperature without complicated procedures, not only abandoned the electrochemically hindered organic stabilizers during the synthesis, but also made the as-prepared catalyst with bimetallic composition strongly couple to graphene nanosheets. Meanwhile, it also provided the catalyst with large surface area and hierarchical pore structures via the spatially interconnected finger-like nanoparticles. As a result, the catalyst exhibited a synergistically enhanced electrocatalytic activity (2025.6 mA/mg Pd ) and stability for methanol electro-oxidation reaction, which was superior to the commercial Pd/C catalyst and the other reported Pd-based catalysts. In addition, the electrocatalytic performances could be easily adjusted by regulating the catalyst composition via this facile synthesis. These findings suggested a straightforward method to prepare the practical electrocatalysts with low cost and high activity for the fuel cell technologies. [ABSTRACT FROM AUTHOR]

In present work, we prepared the bimetallic Cu-Co nanocatalysts on poly (diallyldimethylammonium chloride) functionalized halloysite nanotubes (Cu-Co/PDDA-HNTs) by a deposition-reduction technique at room temperature. The analysis of XRD, SEM, TEM, HAADF-STEM and XPS were employed to systematically investigate the morphology, particle size, structure and surface properties of the nanocomposite. The results reveal that the PDDA coating with thickness of ∼15 nm could be formed on the surface of HNTs, and the existence of PDDA is beneficial to deposit Cu and Co nanoparticles (NPs) with high dispersibility on the surface. While the cost-effective nanocomposite was used for the hydrolytic dehydrogenation of ammonia-borane (NH 3 BH 3 ), the nanocatalyst showed extraordinary catalytic properties with high total turnover frequency of 30.8 mol H2 /(mol metal min), low activation energy of 35.15 kJ mol −1 and high recycling stability (>90% conversion at 10th reuse). These results indicate that the bimetallic Cu-Co nanocatalysts on PDDA functionalized HNTs have particular potential for application in release hydrogen process. [ABSTRACT FROM AUTHOR]

Gold-palladium nanoparticles with an average size of 3.5 nm and controlled compositions were grown on rutile titania nanorods using pulsed laser deposition. The structural properties of the as-synthesized nanoparticles and their interface with the oxide support were studied at the atomic scale using aberration-corrected transmission electron microscopy (TEM). High resolution TEM imaging showed that both polycrystalline Au-Pd particles with droplet morphology and single-crystalline particles with truncated octahedron morphology were stabilized on the nanorods during laser deposition depending on the degree of epitaxy between the nanoparticles and the oxide support. By analyzing the single-crystalline particles formed in the presence of a strong epitaxy, 11 epitaxial relationships between the Au-Pd nanoparticles and their support were identified with the two dominant ones being: Au-Pd (111) [101]//r-TiO2(110) [111] and Au-Pd (100) [101]//r-TiO2 (110) [110]. Catalytic testing of the bimetallic titania-supported Au-Pd nanoparticles in the partial hydrogenation of 1,3-butadiene showed that they were both active and selective for this reaction. An increase in the catalytic stability with the gold content was evidenced. [ABSTRACT FROM AUTHOR]

Copper-palladium bimetallic catalysts supported on TiO 2 were developed for the aqueous phase hydrodeoxygenation (HDO) of glycerol. Na-promoted bimetallic catalysts had higher activity than monometallic catalysts while maintaining high 1,2-propanediol (1,2-PDO ) selectivity (76–93%) characteristic of Cu catalysts. The best results were obtained with CuPd/TiO 2 -Na. At 220 °C and 0.7 MPa H 2 the initial turnover frequency (TOF based on Cu + Pd sites) was 0.14 s −1 ; the selectivity to 1,2-PDO reached 85%. Characterization of the samples was performed by H 2 -temperature programed reduction (H 2 -TPR), X-ray diffraction and high-resolution electron microscopy (HRTEM) plus selected area electron diffraction (SAED), and their results were consistent with the formation of CuPd alloy nanoparticles with their surface enriched in Cu, hence explaining the high selectivity to 1,2-PDO of the bimetallics. The increased activity of the Pd-Cu bimetallic catalysts stems from the significantly smaller average diameter of the CuPd alloy nanoparticles when compared with the Cu or Pd nanoparticles of the monometallic catalysts. Besides the effect upon the nanoparticle structure, Pd promoted HDO in part by the activation of glycerol aqueous phase reforming to produce H 2 at the surface level. Cu was stabilized in the bimetallic samples by the formation of the alloy with Pd and by the presence of Na in the catalyst. As a result, CuPd/TiO 2 -Na can be reused while maintaining high stable activity and 1,2-PDO selectivity. The HDO reaction proceeds through the formation of 1-hydroxy-2-propanone (acetol), followed by its hydrogenation to form 1,2 PDO. Formation of acetol or an acetol-like surface intermediate presumably occurs on support sites, whereas the hydrogenation to 1,2-PDO occurs on the metal sites. The first step is enhanced when basic sites are added to the support, while the hydrogenation step on Cu sites is improved by raising the H 2 pressure and/or by the formation of H 2 via reforming on Pd sites. [ABSTRACT FROM AUTHOR]

The crystal structure of [NiEn]CrO (En is ethylendiamine), CHCrNNiO is studied: a = 9.0408(5) Å, c = 9.7466(4) Å, V = 689.92(8) Å, space group P6/ mmc, Z = 2, d = 1.704 g/cm, Ni-N 2.133(9) Å, ∠N-Ni-N 82.4(5)°. The thermal properties are determined. When it is heated in a hydrogen atmosphere, a mixture of nanocrystalline Ni and CrO powders with coherent scattering regions of 59 nm and 90 nm respectively is formed. It is demonstrated that thermal decomposition products consist of pseudomorphic particles that inherit the sizes and shapes of initial [NiEn]CrO single crystals. [ABSTRACT FROM AUTHOR]

The salt-elimination reaction of the complex [Na2U(bis-salophen)] with metal halides provides an entry to the synthesis of well-defined homobimetallic uranium–uranium and rare heterobimetallic uranium–cobalt and uranium–nickel complexes supported by a redox-active dinucleating ligand. [ABSTRACT FROM AUTHOR]

CNT supported Cu based catalysts were prepared for the selective conversion of biomass-derived furfural to cyclopentanone in aqueous solution. The promotion effect was investigated with the addition of Co, Mo, Zn and Ni in Cu/CNT catalyst. The product distribution was greatly affected by the metal composition. Among those catalysts, CuZn/CNT catalyst exhibited better selectivity toward cyclopentanone with satisfactory furfural conversion in mild condition than other catalysts. The effects of process parameters including metal compositions, reaction temperature, hydrogen pressure on the product distribution were investigated in detail over CuZn/CNT. The surface area, metal composition, surface morphology and acidity of the catalysts were characterized by BET, AAS, XPS, XRD, TEM and NH 3 -TPD. According to the XRD and XPS results, the main species on the CNT surface was mainly Cu 0 . Meanwhile, possible conversion pathways over different catalysts were proposed based on the product distribution. The addition of Zn would be helpful to the cleavage of C O bond and the formation of new C C bond to give the intermediate 2-cyclopentenone, which was further hydrogenated to either cyclopentanone. [ABSTRACT FROM AUTHOR]

PdBi bimetallic catalysts are synthesized while their catalytic activity and stability for formic acid oxidation reaction (FAOR) and direct formic acid fuel cell (DFAFC) performance are evaluated. According to investigations, Pd 2 Bi 1 /C catalyst including low Pd amount promotes oxygen desorption with enhancement in CO poisoning resistance. With that, indirect formic acid oxidation reaction (IFAOR) and its stability are improved. To further improve the FAOR, polyvinylpyrrolidone (PVP) surfactant is contained due to its amphiphilic property reducing Bi aggregation. To determine optimal amount of the PVP, analysis using TEM and XPS is performed and the results are verified by density functional theory (DFT). According to TEM, in 0.22 PVP-Pd 2 Bi 1 /C catalyst, PdBi has small size (∼5 nm) and is well-dispersed with widest E d - E F of 3.85 eV, proving the catalyst induces effective CO-poisoning resistance and less Bi aggregation. These results are also compatible with trend in FAOR measured by cyclic voltammogram (CV). Even long-term stability, the catalyst maintains catalytic activity well. The best performance of DFAFC using the catalyst (32.7 mW cm −2 ·Pd g −1 ) indicates that 0.22 PVP- Pd 2 Bi 1 /C is excellent catalyst for FAOR and DFAFC performances. [ABSTRACT FROM AUTHOR]

The present paper discusses the role of calcination in tuning the non-enzymatic glucose sensitivities of Cu–Ni bimetallic nanocomposites. Nanoparticles of Cu, a layered hydroxide of Ni and Cu–Ni nanocomposites were synthesized via the polyol reduction method. The prepared nanomaterials were thoroughly characterized by X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDS). Thermogravimetric analysis (TGA) was done in order to understand the thermal behavior of the nanoparticles. The prepared nanomaterials were subjected to calcination at three different temperatures viz. 400, 500 and 600 °C. The non-enzymatic glucose sensing activity of the nanomaterials was studied electrochemically. The nanocomposites showed the best sensing performance among the prepared nanomaterials. Interestingly, calcination resulted in a seven-fold increase in the sensitivity of the nanocomposites. The nanocomposite that was calcined at 600 °C showed the maximum sensitivity of 63.87 μA mM−1 cm−2 with a low detection limit of 8 μM at a signal to noise ratio of 3. The nanocomposite showed a distinct linear response in the range of 0.01 to 18 mM with a regression coefficient of 0.99162. The nanocomposite also exhibited excellent selectivity for glucose in the presence of other interfering agents. The nanocomposite also demonstrated good agreement with the pathology laboratory data for whole blood and blood serum samples. [ABSTRACT FROM AUTHOR]

In this article, it aims to propose effective approaches for hydro-forming process of bi-metallic composite pipe by assuming plane strain and elastic-perfectly plastic material model. It derives expressions for predicting hydro-forming pressure and residual stress of the forming process of bi-metallic composite pipe. Test data from available experiments is employed to check the model and formulas. It shows the reliability of the proposed model and formulas impersonally. [ABSTRACT FROM AUTHOR]

The synthesis of bimetallic nanoparticles is gaining attention due to a number of interesting and striking new properties that can be derived from the combination of two metals. In this study, bimetallic silver/copper (Ag/Cu) nanoparticles were prepared by co-reduction method using aqueous leaf extracts of Carica papaya as reducing agent. The synthesized nanoparticles showed a single UV–vis peak with a maximum absorption at 776 nm. The SEM and TEM images of bimetallic Ag/Cu nanoparticles displayed, among others, a unique star-like structure. HR-TEM mapping revealed uniform distribution of Ag & Cu forming a bimetallic nanoparticle. The bimetallic Ag/Cu has an average hydrodynamic particle size of 420.7 nm (DLS) and TEM size of ∼150 nm. The presence of elemental Ag, Cu, C, N and O was confirmed in EDX spectra suggesting nitrogen containing metabolites capping the bimetallic Ag/Cu nanoparticles. The XRD patterns of bimetallic Ag/Cu nanoparticles displayed crystallinity with observed diffraction peaks corresponding to Ag, Ag 2 O and CuO. The synthesized bimetallic nanoparticles were then utilized for water purification application using the toxic pollutant, chlorpyrifos pesticide, as a model. Results showed that bimetallic Ag/Cu nanoparticles are efficient agents to promote degradation of chlorpyrifos in water, indicating the high potential of green synthesized nanometals for purifying water from pesticide contamination. [ABSTRACT FROM AUTHOR]

A simple and facile method is described for the morphology-controlled synthesis of bimetallic Au–Pd alloyed nanochain networks (NNCs) that show high catalytic performance for the Ullmann intermolecular homocoupling of aromatic or alkyl halides (X = I, Br, Cl) in aqueous media and can be reused at least five times, which can also be applied to intramolecular homocoupling. [ABSTRACT FROM AUTHOR]

Hydrothermal approach has led to the formation of a three-dimensional metal-organic framework (MOF), [NiCo(μ 2 -tp)(μ 4 -tp)(4,4′-bpy) 2 ] n ( 1 ) (tp = terephthalic acid and 4,4′-bpy = 4,4′-bipyridine) which was characterized by means of single-crystal X-ray diffraction analysis, powder X-ray diffraction (PXRD), FT-IR spectroscopy, scanning electron microscopy (SEM) and inductive coupled plasma optical emission spectroscopy (ICP-OES). Thermal decomposition of the MOF afforded nanostructured mixed metal oxide, namely NiO/Co 3 O 4 . The XRD and SEM analysis confirm the formation of the mixed metal oxide. The nanostructured NiO/Co 3 O 4 demonstrated good catalytic activity and selectivity in the epoxidation of cyclooctene in the presence of tert -butyl hydroperoxide (TBHP) as oxidant. [ABSTRACT FROM AUTHOR]

The catalytic performance of Cu-Co/Al2O3 in the slurry reactor for direct ethanol synthesis from syngas was investigated. The reduced catalyst and catalyst reacted for 100, 300, 500, and 750 h were characterized by using XRD, TEM, EDS, BET, and ICP-MS techniques. Compared with that in the fixed-bed reactor, the catalyst in the slurry reactor exhibited higher selectivity to ethanol, which was above 70 wt % in the total alcohols. The structure variation of the bimetallic Cu-Co with reaction time is that CuCo2O4 was transformed into Cu-Co alloy after reduction, and Cu-Co alloy was decomposed into Cu and Co after reaction for 100 h. After reaction for 300 h, Co2C started to generate and Cu@Co@Co2C was formed as reacted for 500 h. All of Cu-Co alloy, Cu@Co, and Cu@Co@Co2C are highly selective to ethanol, which was maintained for 750 h. Meanwhile, the slurry solvent of PEG-400 is another reason for the high ethanol selectivity. [ABSTRACT FROM AUTHOR]

Carbon-supported bimetallic nanoparticles, PtNi/C and PtMo/C, were synthesized using the borohydride reduction method and were tested as cathode in the hydrogen evolution reaction (HER) employing acid aqueous solution of 3-triethylammonium-propanesulfonic acid tetrafluoroborate (TEA-PS.BF 4 ) ionic liquid as the electrolyte. For comparison a commercial carbon-supported Pt nanoparticles (Pt/C) has been tested. The morphology, composition and structure of the carbon-supported nanoparticles were characterized by EDX, XRD, and TEM. The results obtained by chronoamperometry, Tafel plots and electrochemical impedance spectroscopy (EIS) exhibited an excellent catalytic effect and the same kinetics mechanism for all carbon-supported nanoparticles in HER studied. Results of Tafel analysis showed that the HER rate determining step is the Volmer–Heyrovsky mechanism. In the temperature range 25–80 °C, the PtNi/C and PtMo/C cathodes presented lower activation energy and higher current density than system using the Pt/C cathode. The PtMo/C cathode improves charge transfer kinetics and hydrogen adsorption, while the PtNi/C cathode facilitates the desorption step. These results demonstrate that the carbon-supported bimetallic nanoparticles PtNi/C and PtMo/C are responsible for increasing the catalytic performances of the HER when TEA-PS.BF 4 aqueous solution is employed as electrolyte. [ABSTRACT FROM AUTHOR]

Supercritical fluid reactive deposition (SFRD) using supercritical carbon dioxide (scCO2) as the solvent and the reaction medium was employed to generate mono- and bi-metallic Pt and Pd nanoparticles (NPs) on SBA-15 as a mesoporous support material. Highly uniform particles in the 5 nm range were deposited preferentially inside the pores detected by transmission electron microscopy (TEM). The materials were further characterized by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). Coupling of Scanning Transmission Electron Microscopy (STEM) with EDX demonstrated the formation of alloy-type structures for the bimetallic Pt/Pd particles. Comparison of the SFRD-process using scCO2 with the impregnation method using conventional liquid solvents showed that the material characteristics were similar to deposition from n-pentane, but significantly different from deposition from toluene or THF. The differences could be rationalized on the basis of characteristic physico-chemical solvent properties. Notably, the choice of solvent during the preparation was also reflected in the catalytic performance of the materials for hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL), whereby the nature of the support and the Pt/Pd ratio were additional parameters controlling the activity with the SFRD approach. Bimetallic Pt/Pd particles were found to result in superior activity as compared to either of the individual monometallic species. Thus, the use of SFRD allows one to avoid organic solvents during the catalyst preparation, leading even to improved catalytic properties in favourable cases. [ABSTRACT FROM AUTHOR]

Controlled synthesis of bimetallic catalysts has attracted much attention in heterogeneous catalysis because their catalytic activity depends on the size of nanoparticles and hence the methods of synthesis. In this work, one convenient method was proposed, with an aim to control the size and dispersion of bimetallic nanoparticles. In this method, Cu (or Ni) configurational ion of hydrotalcites was used as directing reagent, which directed the position and dispersion of the final bimetallic nanoparticles by employing the metal interaction between Cu and Au as the driving force. The size, structure and composition of bimetallic nanoparticles were characterized using techniques of X-ray diffraction (XRD), nitrogen physisorption, X-ray photoelectron spectra (XPS) and scanning transmission electron microscopy (STEM). The mean size of bimetallic AuCu nanoparticles was 2.5 nm, which was 1/4 (Step-impregnation) or 1/10 (Co-impregnation) of that prepared by traditional methods. Even if the loading of Au was increased to 10 wt%, the obtained AuCu nanoparticles were still well dispersed. The catalytic activity of AuCu and AuNi nanoparticles in aerobic oxidation of benzyl alcohol was far higher than those prepared by traditional methods. The mechanism of forming bimetallic nanoparticles was investigated. It was found that the dispersion of Cu (or Ni) and the interaction between Cu (or Ni) and Au are two key factors affecting the dispersion of AuCu (or AuNi) nanoparticles. Graphical Abstract: [ABSTRACT FROM AUTHOR]

Ni–Ce and Ni–Pt bimetallic catalysts supported over α-Al 2 O 3 are synthesized by using co-impregnation method, and then reduced, each via radiolytic process or thermal H 2 -treatment. For Ni-Ce/Al 2 O 3 , the structural study reveals that Ce is alloyed with Ni as Ce 2 Ni 7 nanoparticles in the radiation-reduced catalysts, while it segregates to the surface in the form of CeO 2 in the H 2 -reduced catalysts. For Ni-Pt/Al 2 O 3 radiolytic catalysts, Ni, Pt, NiPt and Ni 3 Pt nanoparticles, which size is 3.5 nm, are observed. When the radiation-reduced samples are tested in the benzene hydrogenation, they both display high conversion rate. However, the Ni-Pt/Al 2 O 3 is more efficient than Ni-Ce/Al 2 O 3 . The performance of the catalysts is correlated with the high dispersion of the metal and the presence of intermetallic Ni–Pt and Ni–Ce phases. It is compared to that of other radiolytic monometallic/oxide catalysts of the literature. [ABSTRACT FROM AUTHOR]

Pd and Ru are two key elements of the platinum-group metals that are invaluable to areas such as catalysis and energy storage/transfer. To maximize the potential of the Pd and Ru elements, significant effort has been devoted to synthesizing Pd–Ru bimetallic materials. However, most of the reports dealing with this subject describe phase-separated structures such as near-surface alloys and physical mixtures of monometallic nanoparticles (NPs). Pd–Ru alloys with homogenous structure and arbitrary metallic ratio are highly desired for basic scientific research and commercial material design. In the past several years, with the development of nanoscience, Pd–Ru bimetallic alloys with different architectures including heterostructure, core-shell structure and solid-solution alloy were successfully synthesized. In particular, we have now reached the stage of being able to obtain Pd–Ru solid-solution alloy NPs over the whole composition range. These Pd–Ru bimetallic alloys are better catalysts than their parent metal NPs in many catalytic reactions, because the electronic structures of Pd and Ru are modified by alloying. In this review, we describe the recent development in the structure control of Pd–Ru bimetallic nanomaterials. Aiming for a better understanding of the synthesis strategies, some fundamental details including fabrication methods and formation mechanisms are discussed. We stress that the modification of electronic structure, originating from different nanoscale geometry and chemical composition, profoundly affects material properties. Finally, we discuss open issues in this field. [ABSTRACT FROM PUBLISHER]

The composition- and structure-controlled synthesis of bimetallic nanostructures is highly important for the design of highly active electrocatalysts. Herein, we report a one-step strategy for the efficient synthesis of bimetallic PtCo nanodendrites at high yield in an aqueous solution at room temperature. The newly designed bimetallic PtCo nanodendrites with a porous dendritic surface offer sufficient molecular accessible active sites and are highly active and durable catalysts for oxygen reduction reaction in comparison with bimetallic PtCo nanoflowers and commercially available Pt/C catalyst. [ABSTRACT FROM AUTHOR]

This work reports hydrodeoxygenation of dibenzofuran into bicyclic hydrocarbons over Cu–Ni catalysts supported on TiO 2 , ZrO 2 and CeO 2 . The supported Cu–Ni catalysts were synthesized using a wet-impregnation method and calcined and reduced at 500 °C in accordance with TGA, DSC, and H 2 -TPR results. The catalyst properties were systematically examined using Raman, XRD, SEM, EDX and XPS techniques. XRD and Raman studies reveal the existence of cubic phase CeO 2 , monoclinic ZrO 2 , anatase TiO 2 , and cubic NiO in the synthesized catalysts. H 2 -TPR results show the simultaneous reduction of Cu 2+ to Cu 0 and Ni 2+ to Ni 0 , forming bimetallic Cu–Ni alloy. Among the supports, a high dispersion of Cu–Ni particles was found on the CeO 2 support, as evidenced by SEM studies. The reduced catalysts were investigated for hydrodeoxygenation of dibenzofuran at 250, 260 and 270 °C at 100 H 2 bar for 6 h. The results show that the conversion of dibenzofuran increases with the increase of temperature: at 250 and 260 °C CuNi/TiO 2 catalyst showed higher dibenzofuran conversions of 96% and 99% than the NiCu/CeO 2 catalyst with relatively low conversions of 89% and 98%, respectively. In contrast, low conversions of 63% and 68% were found for the CuNi/ZrO 2 catalyst under identical reaction conditions. In the case of selectivity to hydrocarbons, NiCu/TiO 2 catalyst showed excellent selectivity to bicyclohexyl compared with that of NiCu/CeO 2 and NiCu/ZrO 2 catalysts at 260 °C. However, in terms of selectivity to bicyclohexyl-1-ene, NiCu/CeO 2 catalyst showed the highest selectivity at 250 °C, while NiCu/ZrO 2 catalyst exhibited the highest selectivity at 260 and 270 °C. [ABSTRACT FROM AUTHOR]

Pluronic F127 and NaBr were used during co-reduction of Pd and Pt precursors to achieve octopodal and dendritic Pd@Pt nanoparticles selectively through preferential capping interactions. Our findings demonstrate that two capping agents can be used to independently manipulate the growth regimes of metals in the synthesis of bimetallic nanostructures. [ABSTRACT FROM AUTHOR]

We report a new methodology for producing monometallic or bimetallic nanoparticles confined within hollow nitrogen-doped porous carbon capsules. The capsules are derived from metal-organic framework (MOF) crystals that are coated with a shell of a secondary material comprising either a metal-tannic acid coordination polymer or a resorcinol-formaldehyde polymer. Platinum nanoparticles are optionally sandwiched between the MOF core and the shell. Pyrolysis of the MOF-shell composites produces hollow capsules of porous nitrogen-doped carbon that bear either monometallic (Pt, Co, and Ni) or alloyed (PtCo and PtNi) metal nanoparticles. The Co and Ni components of the bimetallic nanoparticles are derived from the shell surrounding the MOF crystals. The hollow capsules prevent sintering and detachment of the nanoparticles, and their porous walls allow for efficient mass transport. Alloyed PtCo nanoparticles embedded in the capsule walls are highly active, selective, and recyclable catalysts for the hydrogenation of nitroarenes to anilines. [ABSTRACT FROM AUTHOR]

Bimetallic Ni–Mo alkoxide was synthesized and exploited as the single-source precursor for the solution-processed deposition of the mixed-oxide layers on different conducting surfaces. Upon potential cycling in 1 M NaOH, these composites convert, in situ, into highly porous NiOx/NiOOH catalysts characterized by the high electrocatalytic activity for water oxidation under both basic (pH 13.6) and near neutral (pH 9.2) conditions. [ABSTRACT FROM AUTHOR]

Sono-dispersion of Ni, Co and Ni–Co over Al 2 O 3 –MgO with Al/Mg ratio of 1.5 was prepared and tested for dry reforming of methane. The samples were characterized by XRD, FESEM, PSD, EDX, TEM, BET and FTIR analyses. In order to assess the effect of ultrasound irradiation, Ni–Co/Al 2 O 3 –MgO with Co content of 8% prepared via sonochemistry and impregnation methods. The sono-synthesized sample showed better textural properties and higher activity than that of impregnated one. Comparison of XRD patterns indicated that the NiO peaks became broader by increasing Co content over the support. The FESEM images displayed the particles are small and well-dispersed as a result of sonochemistry method. Also, EDX analysis demonstrated better dispersion of Ni and Co as a result of sonochemistry method in confirmation of XRD analysis. The sono-synthesized Ni–Co/Al 2 O 3 –MgO as a superior nanocatalyst with Co content of 3% illustrates much higher conversions (97.5% and 99% for CH 4 and CO 2 at 850 °C), yields (94% and 96% for H 2 and CO at 850 °C) and 0.97 of H 2 /CO molar ratio in all samples using an equimolar feed ratio at 850 °C. During the 1200 min stability test, H 2 /CO molar ratio remained constant for the superior nanocatalyst. [ABSTRACT FROM AUTHOR]

Herein, we present an ultra-simple one-pot wet-chemistry method for large-scaled synthesis of surface-clean and self-supported bimetallic AuPt nanowire networks (AuPt NWNs) with tunable compositions by using hydrogen bubble as a dynamic template. Hydrogen bubbles are in situ generated from the hydrolysis and oxidation of sodium borohydride which are rapid pouring into the metal precursor solutions. The strategy is very convenient, mild and green, exempted from pressuring, heating, and special apparatus. The resulting AuPt NWNs have clean surfaces, because the gas bubbles do not need to use additional acid/base or organic solvent to remove. Moreover, the as-prepared AuPt NWNs display excellent electrocatalytic activity and durability toward ethanol oxidation and oxygen reduction reactions. [ABSTRACT FROM AUTHOR]

The demands of stricter diesel engine emission regulations have created challenges for current exhaust systems. With advances in low-temperature internal combustion engines and their operations, advances must also be made in vehicle exhaust catalysts. Most current diesel oxidation catalysts use heavy amounts of precious group metals (PGMs) for hydrocarbon (HC), CO, and NO oxidation. These catalysts are expensive and are most often synthesized with poor bimetallic interaction and dispersion. The goal of this work was to study the effect of aging on diesel emission abatement of Pt–Pd bimetallic nanoparticles precisely prepared with different morphologies: well dispersed core–shell vs. well dispersed homogeneously alloyed vs. poorly dispersed, poorly alloyed particles. Alumina and silica supports were studied. Particle morphology and dispersion were analyzed before and after hydrothermal treatments by XRD, EDX, and STEM. Reactivity as a function of aging was measured in simulated diesel engine exhaust. While carefully controlled bimetallic catalyst nanoparticle structure has a profound influence on initial or low temperature catalytic activity, the differences in behavior disappear with higher temperature aging as thermodynamic equilibrium is achieved. The metallic character of Pt-rich alumina-supported catalysts is such that behavior rather closely follows the Pt–Pd metal phase diagram. Nanoparticles disparately composed as well-dispersed core–shell (via seq-SEA), well-dispersed homogeneously alloyed (via co-SEA), and poorly dispersed, poorly alloyed (via co-DI) end up as well alloyed, large particles of almost the same size and activity. With Pd-rich systems, the oxidation of Pd also figures into the equilibrium, such that Pd-rich oxide phases appear in the high temperature forms along with alloyed metal cores. The small differences in activity after high temperature aging can be attributed to the synthesis methods, sequential SEA and co-DI which give rise, after aging, to a bimetallic surface enriched in Pd. [ABSTRACT FROM AUTHOR]

A series of lanthanide complexes of [LnL(H2O)]2− composition where Ln = EuIII, TbIII or GdIII has been studied for determining their photophysical and relaxometric properties in aqueous solution. The bifunctional ligand L (H5BPMNTA) is an acyclic chelator based on a central functionalized 2,2′-bipyridine core and two iminodiacetate coordinating arms. The mono-aqua EuIII and TbIII complexes display attractive spectroscopic properties with an excitation wavelength at 316 nm, similar excited state lifetimes and overall quantum yields (in the ranges 0.5–0.6 ms and 10–13%, respectively) in Tris buffer (pH 7.4). The proton longitudinal relaxivity, r1, of the GdIII complex is 4.4 mM−1 s−1 at 20 MHz and 310 K, which is comparable to that of the clinically used Gd-DTPA (Magnevist®). Interestingly, the water exchange rate between the coordination site and the bulk solvent is very fast (Kex = 2.6 × 108 s−1 at 310 K). The ability of the complex to bind non-covalently to human serum albumin (HSA) was also examined by relaxometric measurements. We also report the synthesis and properties of a bimetallic complex based on Gd-BPMNTA and ReI(bpy)(CO)3 components. In this system, the Re core exhibits interesting photophysical properties (λem = 588 nm, Φ = 1.4%) and the Gd-BPMNTA core displays improved relaxivity (r1 = 6.6 mM−1 s−1 at 20 MHz and 310 K), due to an increase of the rotational correlation time. Besides these appealing optical and relaxometric properties, the presence of a reactive function on the structure proposes this potential dual imaging probe for conjugation to biomolecules or nanomaterials. [ABSTRACT FROM AUTHOR]

This study designs Ni-Mg bimetallic catalysts for preparation of multi-walled carbon nanotubes (MWCNTs) from polypropylene (PP). The study further investigates the influence of Mg content on the catalytic activity of Ni catalyst. It is found that bimetallic Ni-Mg catalysts have higher reduction temperature, smaller Ni particle size and improved stability. Consequently, the addition of Mg not only enhances the yield of MWCNTs, but simultaneously improves the morphology and graphitization of MWCNTs. The activities of the bimetallic Ni-Mg catalysts are dependent on their composition. Among the different Ni-Mg bimetallic catalysts ration, Ni-Mg catalyst shows the highest activity when the ratio of Ni/Mg is 9/1. Moreover, the obtained MWCNTs presents smooth surface with highest graphitization degree. With our bimetallic Ni-Al catalyst, it is promising to achieve mass production of MWCNTs by using waste polymers as feedstock. In this study, Mg is introduced to Ni catalyst as a promoter to improve catalytic activity for the preparation of multi-walled carbon nanotubes (MWCNTs) from polypropylene. The interaction between NiO and MgO plays a crucial role in improving stability and decreasing the size of NiO particles. Consequently, the yield and graphitization degree of MWCNTs are both enhanced by the addition of Mg. [ABSTRACT FROM AUTHOR]

Developing efficient catalysts for electrolysis, in particular for the oxygen evolution in the anodic half cell reaction, is an important challenge in energy conversion technologies. By taking inspiration from the catalytic properties of single-atom catalysts and metallo-proteins, we exploit the potential of metal–organic networks as electrocatalysts in the oxygen evolution reaction (OER). A dramatic enhancement of the catalytic activity toward the production of oxygen by nearly 2 orders of magnitude is demonstrated for novel heterobimetallic organic catalysts compared to metallo-porphyrins. Using a supramolecular approach we deliberately place single iron and cobalt atoms in either of two different coordination environments and observe a highly nonlinear increase in the catalytic activity depending on the coordination spheres of Fe and Co. Catalysis sets in at about 300 mV overpotential with high turnover frequencies that outperform other metal–organic catalysts like the prototypical hangman porphyrins. [ABSTRACT FROM AUTHOR]

The tuning of metal-metal interactions in multinuclear assemblies is a challenge. Selective P coordination of a redox-active PNO ligand to AuI followed by homoleptic metalation of the NO pocket with NiII affords a unique trinuclear Au-Ni-Au complex. This species features two antiferromagnetically coupled ligand-centered radicals and a double intramolecular d8-d10 interaction, as supported by spectroscopic, single-crystal X-ray diffraction, and computational data. A corresponding cationic dinuclear Au-Ni analogue with a stronger d8-d10 interaction is also reported. Although both heterobimetallic structures display rich electrochemistry, only the trinuclear Au-Ni-Au complex facilitates electrocatalytic C−X bond activation of alkyl halides in its doubly reduced state. Hence, the presence of a redox-active ligand framework, an available coordination site at gold, and the nature of the nickel-gold interaction appear to be essential for this reactivity. [ABSTRACT FROM AUTHOR]

A catalytic process including formaldehyde oxidation and benzene “storage-oxidation” cycling for simultaneously removal of formaldehyde and benzene is proposed, by using HZSM-5 supported PtAg bimetallic catalysts. HZSM-5 with different crystal size supported PtAg bimetallic catalysts were synthesized with the investigation focusing on HCHO oxidation at room temperature, benzene storage capacity at room temperature, and benzene catalytic oxidation at elevated temperature. Crystal size of HZSM-5 zeolite not only influences the dispersion of active metals of PtAg, and therefore influence their catalytic properties for formaldehyde and benzene oxidation, but also has great effects on benzene storage capacity and the thermal stability of the stored benzene, which is directly related to the release of benzene at elevated temperature. The ratio of Pt/Ag has an opposite effect on benzene storage capacity and formaldehyde and benzene oxidation properties. Considering these factors, PtAg (Pt/Ag = 1/1) supported on nanoscale HZSM-5 catalysts were found to be suitable for the proposed cycling process, good carbon balances being obtained for each cycle without the production of secondary pollutants. [ABSTRACT FROM AUTHOR]

Thermodynamic control and aromaticity driven instantaneous reaction strategy co-jointly result in three noble-metal based bimetallic nanostructures (namely Au-Pt, Au-Pd and Pd-Pt) through a surfactant-free pathway. Non-aromatic hantzsch 2, 4-dihydropyridine ester (DHPE) is proposed here as a reducing agent and in turn through the acquirement of aromaticity, DHPE provides a general route for the fast synthesis of these bimetallic nanoparticles. The Au-M (M=Pd, Pt) nanostructures are of typically core-shell type structure where Au forms the core and the shell is made of either Pd or Pt. Overwhelmingly, the same synthetic strategy leads to the formation of alloy nanostructures for Pd-Pt. The growth kinetics, reaction mechanism as well as the morphology of the particles could be supported with the redox properties of the precursor salts. The well-recognized catalytic activity of both Pt and Pd has been capitalized here in Pd-Pt alloy particles, which bring synergistic effect to engender its highest electrocatalytic performance and stability towards ethylene glycol oxidation reaction in comparison to the other electrocatalysts (Au-Pd, Au-Pt and commercial Pt/C). In addition, as-synthesized highly electroactive material Pd-Pt becomes an electrochemical sensor for explosive 2, 4 dinitrotoluene (DNT) with an impressive limit of detection (LOD) of ∼0.82 μM. [ABSTRACT FROM AUTHOR]

Pt and PtSn catalysts were studied for n-butanol electro-oxidation at various temperatures. PtSn showed a higher activity towards butanol electro-oxidation compared to Pt in acidic media. The onset potential for n-butanol oxidation on PtSn is ∼520 mV lower than that found on Pt, and significantly lower activation energy was found for PtSn compared with that for Pt. [ABSTRACT FROM AUTHOR]

Controlling the elemental composition of Pt-based bimetallic nanostructures plays an important role in catalytic activity. Herein, we synthesized Pt-Ag bimetallic nanochains with various compositions via bipolar pulsed discharges in water. The composition of Pt-Ag bimetallic nanochains was controlled by varying the pulse duration in a range from 1.3 to 2.3 μs, which could determine the different plasma-assisted oxidation states and subsequent decomposition of the oxide layer that was dependent on the thermal parameters of Pt and Ag. The transmission electron microscopy revealed that the nanochain structure was constructed via the attachment of Pt-Ag alloyed nanoparticles. With increasing Ag content, the higher binding energy of the Pt 4 f peak in the XPS spectra due to the electron transfer from Ag to Pt atoms was observed, and subsequently the Ag 2 O to metallic Ag ratio increased. The electrochemical measurements for methanol oxidation revealed that the electrocatalytic activity, stability and durability of the Pt 71 Ag 29 bimetallic nanoparticles were superior, which could be attributed to the synergistic effect of the Ag oxide and the downshift of the d -band center via electronic modification. [ABSTRACT FROM AUTHOR]