Bimetallic Compounds Research Articles

Composite Nitride Nanoceramics in the System Titanium Nitride (TiN)-Aluminum Nitride (AlN) through High Pressure and High Temperature Sintering of Synthesis-Mixed Nanocrystalline Powders.

Presented is a study on the original preparation of individual and in situ intimately mixed composite nanocrystalline powders in the titanium nitride-aluminum nitride system, Ti:Al = 1:1 (at.), which were used in high pressure (7.7 GPa) and high temperature (650 and 1200 °C) sintering with no binding additives for diverse individual and composite nanoceramics. First, variations in precursor processing pathways and final nitridation temperatures, 800 and 1100 °C, afforded a pool of mixed in the nanosized regime cubic TiN (c-TiN) and hexagonal AlN (h-AlN) composite nanopowders both with varying average crystallite sizes. Second, the sintering temperatures were selected either to preserve initial powder nanocrystallinity (650 °C was lower than both nitridation temperatures) or promote crystal growth and recrystallization (1200 °C was higher than both nitridation temperatures). Potential equilibration towards bimetallic compounds upon solution mixing of the organometallic precursors to nanopowders, monomeric Ti[N(CH3)2]4 and dimeric {Al[N(CH3)2]3}2, was studied with 1H and 13C NMR in C6D6 solution. The powders and nanoceramics, both of the composites and individual nitrides, were characterized if applicable by powder XRD, FT-IR, SEM/EDX, Vicker’s hardness, and helium density. The Vicker’s hardness tests confirmed many of the composite and individual nanoceramics having high hardnesses comparable with those of the reference h-AlN and c-TiN ceramics. This is despite extended phase segregation and, frequently, closed microsized pore formation linked mainly to the AlN component. No evidence was found for metastable alloying of the two crystallographically different nitrides under the applied synthesis and sintering conditions. The high pressure and high temperature sintering of the individual and in situ synthesis-mixed composite nanopowders of TiN-AlN was demonstrated to yield robust nanoceramics.

Crystal structures of [Cu(phen)(H2O)3(MF6)]·H2O (M = Ti, Zr, Hf) and [Cu(phen)(H2O)2F]2[HfF6]·H2O.

The crystal structures of three bridged bimetallic mol-ecular compounds, namely, tri-aqua-2κ3 O-μ-fluorido-penta-fluorido-1κ5 F-(1,10-phenanthroline-2κ2 N,N')copper(II)titanium(IV) monohydrate, [Cu(TiF6)(phen)(H2O)3]·H2O (phen is 1,10-phenanthroline, C12H8N2), (I), tri-aqua-2κ3 O-μ-fluorido-penta-fluorido-1κ5 F-(1,10-phenanthroline-2κ2 N,N')copper(II)zirconium(IV) monohydrate, [Cu(ZrF6)(phen)(H2O)3]·H2O, (II), and tri-aqua-2κ3 O-μ-fluorido-penta-fluorido-1κ5 F-(1,10-phenanthroline-2κ2 N,N')copper(II)hafnium(IV) monohydrate, [Cu(HfF6)(phen)(H2O)3]·H2O, (III), and one mol-ecular salt, bis-[diaqua-fluorido-(1,10-phenanthroline-κ2 N,N')copper(II)] hexa-fluorido-hafnate(IV) dihydrate, [CuF(phen)(H2O)2]2[HfF6]·2H2O, (IV), are reported. The bridged bimetallic compounds adopt Λ-shaped configurations, with the octa-hedrally coordinated copper(II) center linked to the fluorinated early transition metal via a fluoride linkage. The extended structures of these Λ-shaped compounds are organized through both intra- and inter-molecular hydrogen bonds and inter-molecular π-π stacking. The salt compound [Cu(phen)(H2O)2F]2[HfF6]·H2O displays an isolated square-pyramidal Cu(phen)(H2O)2F+ complex linked to other cationic complexes and isolated HfF6 2- anions through inter-molecular hydrogen-bonding inter-actions.

Towards self-doping multimetal porphyrin systems

An approach for the possible production of novel bimetallic self-doped porphyrin-based compounds of potential interest in material science is reported. Heating Cu(II)tetraphenylporphyrin (TPPCu) with chromocene at 120°C in benzonitrile affords the crystalline multimetal porphyrin system TPPCu/TPPCr in good yield. The X-ray single crystal structural analysis reveals a random distribution of TPPCu and TPPCr, with a Cu:Cr ratio of 71(2):29(2)%. Exploratory DFT calculations of TPPCu/TPPCr indicate little if any electron transfer. In contrast, calculations of a hypothetical cationic TPPCu/TPPRu system indicates the possibility of self-doping.

New Fe–Cu bimetallic coordination compounds based on ω-ferrocene carboxylic acids and 2-thioimidazol-4-ones: structural, mechanistic and biological studies

Synthesis, characterization and in vitro cytotoxic investigation of a series of new ferrocene-containing derivatives based on ω-ferrocene carboxylic acids and 2-alkylthioimidazolin-4-ones and their copper complexes have been reported.

A simple and high-yield route to iridium, rhodium, osmium and ruthenium nido-6-metalladecaborane compounds.

We report a high-yield heterogeneous solid/liquid phase synthetic method to a series of nido-6-metalladecaboranes. The hydridoirida- and hydridorhoda-decaboranes, [6,6,6-H(PPh3)2-nido-6-MB9H13] [M = Ir (1), Rh (2)] are isolatable in 98% yields from the reaction of the square-planar M(I) complexes, [MCl(PPh3)3] (M = Rh, Ir), with K[B9H14]. The same synthetic procedure, but using [MCl(CO)H(PPh3)3] (M = Ru, Os) as metal starting reagents produces the CO-ligated clusters, [6,6,6-(CO)(PPh3)2-nido-6-MB9H13] [M = Ru (3), Os (4)], in yields of 83% and 95%, respectively. These highly convenient syntheses permit the investigation of the reaction chemistry of the new nido-6-metalladecaboranes. Thus, the CO-ligated compounds, 3 and 4, react with the square-planar platinum(II) complex, [PtCl2(PMe2Ph)2], in the presence of potassium triethylborohydride, to give the bimetallic clusters, [1,1,1-(CO)H(PPh3)-isocloso-1-RuB9H8-μ-(1,2)-{Pt(PMe2Ph)2}] (5) and [7,7-(PMe2Ph)2-9,9,9-(CO)(PPh3)2-nido-7,9-PtOsB9H11] (6), and the monometallic nido-5-osamadecaborane, [5,5,5-(PPh3)2(CO)-nido-5-OsB9H13] (7). This reactivity illustrates the potential of polyhedral boron-based clusters as molecular scaffolds ("B-frames") for the construction of multimetallic species. Single-crystal X-ray diffraction analyses have revealed the molecular structures of 3, 5, 6 and 7; the compounds are also studied by multielement NMR spectroscopy, mass spectrometry, IR spectroscopy, and in some cases computationally. Futhermore, the rotation of the {M(X)(PR3)2} moiety (X = H, CO), as PH3-ligated models, is studied by means of DFT-calculated relaxed potential energy surface scans, giving some insight into the lability of the metal-to-borane fragment interaction and of the exo-polyhedral ligands.

Synthesis of Zn-Li Bimetallic Compound and Its Catalytic Application in Hydroboration of Isocyanate

Synthesis of Zn-Li Bimetallic Compound and Its Catalytic Application in Hydroboration of Isocyanate

Construction of Hybrid Bimetallic Uranyl Compounds Based on a Preassembled Terpyridine Metalloligand.

Six hybrid uranyl-transition metal compounds [UO2 Ni(cptpy)2 (HCOO)2 (DMF)(H2 O)] (1), [UO2 Ni(cptpy)2 (BTPA)2 ] (2), [UO2 Fe(cptpy)2 (HCOO)2 (DMF)(H2 O)] (3), [UO2 Fe(cptpy)2 (BTPA)2 ] (4), [UO2 Co(cptpy)2 (HCOO)2 (DMF)(H2 O)] (5), and [UO2 Co(cptpy)2 (BTPA)2 ] (6), based on bifunctional ligand 4'-(4-carboxyphenyl)-2,2':6',2''-terpyridine (Hcptpy) are reported (H2 BTPA = 4,4'-biphenyldicarboxylic acid). Single-crystal XRD revealed that all six compounds feature similar metalloligands, which consist of two cptpy- anions and one transition metal cation. The metalloligand M(cptpy)2 can be considered to be an extended linear dicarboxylic ligand with length of 22.12 Å. Compounds 1, 3, and 5 are isomers, and all of them feature 1D chain structures. The adjacent 1D chains are connected together by hydrogen bonds and π-π interactions to form a 3D porous structure, which is filled with solvent molecules and can be exchanged with I2 . Compounds 2, 4, and 6 are also isomers, and all of them feature 2D honeycomb (6,3) networks with hexagonal units of dimensions 41.91×26.89 Å, which are the largest among uranyl compounds with honeycomb networks. The large aperture allows two sets of equivalent networks to be entangled together to result in a 2D+2D→3D polycatenated framework. Remarkably, these uranyl compounds exhibit high catalytic activity for cycloaddition of carbon dioxide. Moreover, the geometric and electronic structures of compounds 1 and 2 are systematically discussed on the basis of DFT calculations.

Development and Optimization of Tin/Flux Mixture for Direct Tinning and Interfacial Bonding in Aluminum/Steel Bimetallic Compound Casting.

Interfacial bonding highly affects the quality of bimetallic bearing materials, which primarily depend upon the surface quality of a solid metal substrate in liquid–solid compound casting. In many cases, an intermediate thin metallic layer is deposited on the solid substrate before depositing the liquid metal, which improves the interfacial bonding of the opposing materials. The present work aims to develop and optimize the tinning process of a solid carbon steel substrate after incorporating flux constituents with the tin powder. Five ratios of tin-to-flux—i.e., 1:1, 1:5, 1:10, 1:15, and 1:20—were used for tinning process of carbon steel solid substrate. Furthermore, the effect of volume ratios of liquid Al-based bearing alloy to solid steel substrate were also varied—i.e., 5:1, 6.5:1 and 8.5:1—to optimize the microstructural and mechanical performance, which were evaluated by interfacial microstructural investigation, bonding area determination, hardness and interfacial strength measurements. It was found that a tin-to-flux ratio of 1:10 offered the optimum performance in AlSn12Si4Cu1/steel bimetallic materials, showing a homogenous and continuous interfacial layer structure, while tinned steels using other percentages showed discontinuous and thin layers, as in 1:5 and 1:15, respectively. Furthermore, bimetallic interfacial bonding area and hardness increased by increasing the volume ratio of liquid Al alloy to solid steel substrate. A complete interface bonding area was achieved by using the volume ratio of liquid Al alloy to solid steel substrate of ≥8.5.

Insights into Molecular Magnetism in Metal-Metal Bonded Systems as Revealed by a Spectroscopic and Computational Analysis of Diiron Complexes.

A pair of bimetallic compounds featuring Fe-Fe bonds, [Fe(iPrNPPh2)3FeR] (R = PMe3, ≡NtBu), have been investigated using High-Frequency Electron Paramagnetic Resonance (HFEPR) as well as field- and temperature-dependent 57Fe nuclear γ resonance (Mössbauer) spectroscopy. To gain insight into the local site electronic structure, we have concurrently studied a compound containing a single Fe(II) in a geometry analogous to that of one of the dimer sites. Our spectroscopic studies have allowed for the assessment of the electronic structure via the determination of the zero-field splitting and 57Fe hyperfine parameters for the entire series. We also report on our efforts to correlate structure with physical properties in metal-metal bonded systems using ligand field theory guided by quantum chemical calculations. Through the insight gained in this study, we discuss strategies for the design of single-molecule magnets based on polymetallic compounds linked via direct metal-metal bonds.

Recent Progress on NiFe-Based Electrocatalysts for the Oxygen Evolution Reaction.

The seriousness of the energy crisis and the environmental impact of global anthropogenic activities have led to an urgent need to develop efficient and green fuels. Hydrogen, as a promising alternative resource that is produced in an environmentally friendly and sustainable manner by a water splitting reaction, has attracted extensive attention in recent years. However, the large-scale application of water splitting devices is hindered predominantly by the sluggish oxygen evolution reaction (OER) at the anode. Therefore, the design and exploration of high-performing OER electrocatalysts is a critical objective. Considering their low prices, abundant reserves, and intrinsic activities, NiFe-based bimetal compounds are widely studied as excellent OER electrocatalysts. Moreover, recent progress on NiFe-based OER electrocatalysts in alkaline environments is comprehensively and systematically introduced through various catalyst families including NiFe-layered hydroxides, metal-organic frameworks, NiFe-based (oxy)hydroxides, NiFe-based oxides, NiFe alloys, and NiFe-based nonoxides. This review briefly introduces the advanced NiFe-based OER materials and their corresponding reaction mechanisms. Finally, the challenges inherent to and possible strategies for producing extraordinary NiFe-based electrocatalysts are discussed.

TWO-LAYER STEEL FOR CRITICAL METAL STRUCTURES

The paper discusses main methods for obtaining and application of large-sized bimetal: batch rolling, electric arc welding, electroslag surfacing with subsequent rolling, explosion welding. Test results of double-layer steels sheets and experience in bimetal production prove this technology availability for critical metal structures in petrochemical and nuclear engineering or shipbuilding. The universality of the industrial explosion welding allows production of wide range bimetal compounds of 100% integrity both for a single sheet and large-tonnage lots (several hundred tons) and practically unlimited sizes. The features of heat treatment for various bimetals after explosion welding are presented.

A novel viewpoint on the surface adsorbed oxygen and the atom doping in the catalytic oxidation of toluene over low-Pt bimetal catalysts

The low-Pt bimetal compounds (PtNi3-C and PtFe3-C) were synthesized via the chemical reduction method and the toluene catalytic oxidation experiments were conducted to test their catalytic performance. The sample of PtFe3-C (T100 = 255 ℃) possessed a better low-temperature catalytic activity than PtNi3-C (T100 = 288 ℃) due to a higher content of Pt (0), while both two catalysts had a desirable catalytic stability (⁓100 % within 72 h). The reaction kinetic parameters were acquired from the Mars-van Krevelen (MVK) model, and the MVK mechanism combined with the in-situ DRIFT was used to investigate the reaction pathway. Moreover, the theoretical calculations based on DFT was applied to study the accessibility of toluene to the surface of metal atoms doping. Herein, this study not only can provide a promising catalyst with the superior low-temperature catalytic activity and stability, but also can give a comprehensive understanding on the toluene catalytic oxidation mechanism over bimetal catalysts.

Investigation of the Influence of Dynamic Parameters on the Formation, Structure and Properties of Bimetallic Compounds during Explosion Welding with Simultaneous Stamping

This article reports on the study of the influence of dynamic parameters on the formation, structure and properties of bimetallic compounds during explosion welding with simultaneous stamping. The results of the study of the impact of the collision speed and contact speed on the strength, wave parameters and the amount of molten metal obtained by the explosion of a bimetallic compound of the iron + steel 3 alloy are presented. It is shown that the formation of a bimetal during explosion welding is significantly influenced by impact velocity, with an increase in which there is an increase in the values of the maximum deflection and radial deformation.

Free-standing bimetallic CoNiTe2 nanosheets as efficient catalysts with high stability at large current density for oxygen evolution reaction

Abstract The oxygen evolution reaction (OER) step for water splitting requires highly efficient, low-cost and stable catalysts. As efficient catalytic materials for OER, bimetallic telluride (CoNiTe2/NF) nanosheets are prepared by the combination of hydrothermal and calcination method in this work. The physicochemical characterizations confirm that the surface of CoNiTe2/NF is covered by bimetallic telluride compounds (CoNiTe2) with 3D morphology composed of thin and defective nanosheets that are well-distributed on nickel foam (NF). Notably, it shows very low overpotential at 10 (181 mV), 500 (230 mV) and 1000 (270 mV) mA cm−2 and low Tafel slope (44 mV dec−1). Besides, it also exhibits excellent durability lasting 24 h at 100, 500 and 1000 mA cm−2, respectively, without distinct deactivation. This outstanding performance could be due to the bimetallic telluride and the strong covalency around the CoNi center caused by Te that plays a crucial role for enhancing the activity of catalyst. The unique morphology could provide large electrochemical active area and exposure higher amounts of active sites. Meanwhile, the self-supported structure, without binders, could also enhance the performance for OER. This work thus provides a promising strategy to synthesize multi-metal telluride materials as highly efficient and stable catalyst for OER at large current density.

Preparation, structure and properties of a novel bimetallic erbium-mercury compound with upconversion photoluminescence

A novel two-dimensional (2-D) bimetallic erbium-mercury compound {[Er(IA)(HIA)2(H2O)2]2(Hg3Br8)} n (nHgBr2)·2nNO3 (denoted as 1; HIA = isonicotinic acid; IA = isonicotinato anion) was prepared and characterized. Compound 1 crystallizes in the space group P2/c of the monoclinic system. By using solid state samples, it was observed that there are three upconversion photoluminescence emission bands at 400 nm, 475 nm and 526 nm, of which the band at 526 nm is the strongest. These bands can be attributed to the 4 F 9/2 → 4 I 15/2, 4 F 7/2 → 4 I 15/2 and 2 H 11/2 → 4 I 15/2 transitions of the Er3+ ions, respectively. An energy transfer mechanism of the photoluminescence emission bands was described with the energy state diagram of the Er3+ ion and the isonicotinic acid molecule. Compound 1 is characteristic of CIE (Commission Internationale de I'Éclairage) chromaticity coordinates of 0.1479 and 0.4321 in the green region. Compound 1 shows a wide optical band gap of 2.39 eV.

Copper and copper-manganese 1D coordination polymers: Synthesis optimization, crystal structure and preliminary studies as catalysts for Baylis–Hillman reactions

This work reports the influence of experimental parameters (pH and counter-ion) in the synthesis of the 1D coordination polymer [Cu(IDA)(H2O)2]n (IDA = iminodiacetate), named here Cu-IDA. Copper-manganese bimetallic coordination polymers were also obtained by isomorphic replacement into Cu-IDA structure, with different molar ratio of Cu2+ and Mn2+ ions, denoted here as Cu/Mn-IDA (0.9/0.1; 0.7/0.3 and 0.5/0.5). New coordination polymers are isostructural to Cu-IDA and amounts of manganese atoms inserted into crystalline structure were evaluated by single-crystal X-ray diffraction and Rietveld refinement. All coordination polymers obtained were also characterized by infrared absorption spectroscopy and thermogravimetric analysis. Homometallic and bimetallic compounds were evaluated as catalysts for Baylis-Hillman reaction with yields and reaction times comparable or superior to those in the literature. Compounds containing manganese cations shows higher catalytic performance, especially Cu/Mn-IDA (0.9/0.1) with yield 91% in 5 h of reaction. Results also indicate an important role played by the metallic centre in the catalytic mechanism.

Enhanced metallicity boosts hydrogen evolution capability of dual-bimetallic Ni–Fe nitride nanoparticles

Enriching electrocatalysts with uncommon definite functions are of great influence but remains extraordinarily challenging. Upon the excellent metallic characteristics of transition metal nitrides (TMN), the unfavorable d-band energy level severely hinders their hydrogen evolution reaction (HER) catalytic properties. Herein, an enhanced metallicity concept is introduced to address this issue. We strongly enable bimetallic Ni2Fe2N with outstanding alkaline HER capability by making more metallic through in situ hybridization of another bimetallic compound, Ni3Fe. The enhanced metallicity Ni2Fe2N/Ni3Fe hybrid displays nearly 200% enhancement in alkaline HER catalytic activity compared to pristine Ni2Fe2N at a current density of 10 mA cm−2. Experimental and theoretical analyses, as well as crystal field diagram persistently show that the enhanced HER catalytic properties is attributed to the enhanced metallic nature and synergistic effect, endowing strong electronic interaction between Ni2Fe2N and Ni3Fe. The strong electronic interaction enables low adsorption energy and a reasonable shift in the d-orbital, which helps in facilitating water dissociation and H-desorption. This present study offers a useful pathway for the rational design of other catalysts for HER and beyond.

Recyclable cobalt-molybdenum bimetallic carbide modified separator boosts the polysulfide adsorption-catalysis of lithium sulfur battery

The polysulfide shuttling and sluggish redox kinetics, due to the notorious adsorption-catalysis underperformance, are the ultimate obstacles of the practical application of lithium-sulfur (Li-S) batteries. Conventional carbon-based and transition metal compound-based material solutions generally suffer from poor catalysis and adsorption, respectively, despite the performance gain in terms of the other. Herein, we have enhanced polysulfide adsorption-catalytic capability and protected the Li anode using a complementary bimetallic carbide electrocatalyst, Co3Mo3C, modified commercial separator. With this demonstration, the potentials of bimetal compounds, which have been well recognized in other environmental catalysis, are also extended to Li-S batteries. Coupled with this modified separator, a simple cathode (S/Super P composite) can deliver high sulfur utilization, high rate performance, and excellent cycle stability with a low capacity decay rate of ∼0.034% per cycle at 1 C up to 1000 cycles. Even at a high S-loading of 8.0 mg cm−2 with electrolyte/sulfur ratio=6 mL g−1, the cathode still exhibits high areal capacity of ∼6.8 mA h cm−2. The experimental analysis and the first principles calculations proved that the bimetallic carbide Co3Mo3C provides more binding sites for adsorbing polysulfides and catalyzing the multiphase conversion of sulfur/polysulfide/sulfide than monometallic carbide Mo2C. Moreover, the modified separator can be reutilized with comparable electrochemical performance. We also showed other bimetallic carbides with similar catalytic effects on Li S batteries and this material family has great promise in different energy electrocatalytic systems.

Direct Synthesis of Intermetallic Platinum-Alloy Nanoparticles Highly Loaded on Carbon Supports for Efficient Electrocatalysis.

Compared to nanostructured platinum (Pt) catalysts, ordered Pt-based intermetallic nanoparticles supported on a carbon substrate exhibit much enhanced catalytic performance, especially in fuel cell electrocatalysis. However, direct synthesis of homogeneous intermetallic alloy nanocatalysts on carbonaceous supports with high loading is still challenging. Herein, we report a novel synthetic strategy to directly produce highly dispersed MPt alloy nanoparticles (M = Fe, Co, or Ni) on various carbon supports with high catalyst loading. Importantly, a unique bimetallic compound, composed of [M(bpy)3]2+ cation (bpy = 2,2'-bipyridine) and [PtCl6]2- anion, evenly decomposes on carbon surface and forms uniformly sized intermetallic nanoparticles with a nitrogen-doped carbon protection layer. The excellent oxygen reduction reaction (ORR) activity and stability of the representative reduced graphene oxide (rGO)-supported L10-FePt catalyst (37 wt %-FePt/rGO), exhibiting 18.8 times higher specific activity than commercial Pt/C catalyst without degradation over 20 000 cycles, well demonstrate the effectiveness of our synthetic approach toward uniformly alloyed nanoparticles with high homogeneity.

Bimetallic Salen-Based Compounds and Their Potential Applications

The new bimetallic coordination compounds [LNiAg(NO3)], [LCuMn(NO3)2], [LCuCu(NO3)2], [LCuZn(NO3)2], and [{LCuBi(NO3)3}(ACN)] have been synthesized from a salen-type ligand L containing two distinc...