Alloy Nano Research Articles

FeNi3 Nanoparticle for the Localization of Temporal Lobe Epilepsy by MRI

From the perspective of targeting factors, iron acetylacetonate and nickel acetylacetonate were used as major materials, and oleylamine was used as a solvent. Through thermal decomposition, the uniformly distributed nanoparticle FeNi3 was obtained. Then, the α-methyltryptophan (AMT) was used to modify FeNi3, thereby the material (FeNi3-AMT) would be biocompatible. The prepared material was used as a targeting factor to explore whether it could target the epileptogenic focus in temporal lobe epilepsy model rats. In the experiment, the animal models of temporal lobe epilepsy were constructed by using the lithium chloride-pirocarpine method. According to the injection of the nuclear magnetic factor, the models were divided into the FeNi3 group, the FeNi3-AMT group, and the saline group. The model rats received intravenous injections 48 hours after the onset of epilepsy. The activity of the epileptic seizure sites before and after injection, the penetration of nanoparticles, and the toxic and side effects of the material were compared. The results showed that the rat models of temporal lobe epilepsy were successfully constructed (the success rate was more than 85%). Meanwhile, the epilepsy lesions of the rat models added with nanoparticles were darker (P < 0.05). The staining of rat brain sections confirmed the distribution of iron particles. In the FeNi3-AMT group, there were more iron particles distributed (P < 0.05). In addition, various abnormal neurons appeared in the hippocampus of the three groups, and there was no significant difference between the different groups (P < 0.05). There was no significant difference in the number of positive neurons in the CA3 region of the brain between different groups (P < 0.05). However, the imaging effect based on FeNi3-AMT was more prominent (P < 0.05), which confirmed that the FeNi3-AMT group had better targeting location effects. The study confirmed that the iron nano alloy particle material had excellent application values in the localization of temporal lobe epilepsy.

A Single-Atom Manipulation Approach for Synthesis of Atomically Mixed Nanoalloys as Efficient Catalysts.

Synthesis of well-defined atomically mixed alloy nanoparticles on desired substrates is an ultimate goal for their practical application. Herein we report a general approach for preparing atomically mixed AuPt, AuPd, PtPd, AuPtPd NAs(nanoalloys) through single-atom level manipulation. By utilizing the ubiquitous tendency of aggregation of single atoms into nanoparticles at elevated temperatures, we have synthesized nanoalloys on a solid solvent with CeO2 as a carrier and transition-metal single atoms as an intermediate state. The supported nanoalloys/CeO2 with ultra-low noble metal content (containing 0.2 wt % Au and 0.2 wt % Pt) exhibit enhanced catalytic performance towards complete CO oxidation at room temperature and remarkable thermostability. This work provides a general strategy for facile and rapid synthesis of well-defined atomically mixed nanoalloys that can be applied for a range of emerging techniques.

A Single‐Atom Manipulation Approach for Synthesis of Atomically Mixed Nanoalloys as Efficient Catalysts

AbstractSynthesis of well‐defined atomically mixed alloy nanoparticles on desired substrates is an ultimate goal for their practical application. Herein we report a general approach for preparing atomically mixed AuPt, AuPd, PtPd, AuPtPd NAs(nanoalloys) through single‐atom level manipulation. By utilizing the ubiquitous tendency of aggregation of single atoms into nanoparticles at elevated temperatures, we have synthesized nanoalloys on a solid solvent with CeO2 as a carrier and transition‐metal single atoms as an intermediate state. The supported nanoalloys/CeO2 with ultra‐low noble metal content (containing 0.2 wt % Au and 0.2 wt % Pt) exhibit enhanced catalytic performance towards complete CO oxidation at room temperature and remarkable thermostability. This work provides a general strategy for facile and rapid synthesis of well‐defined atomically mixed nanoalloys that can be applied for a range of emerging techniques.

Influence of phosphorus on the electrocatalytic activity of palladium nickel nanoalloy supported on N-doped reduced graphene oxide for ethanol oxidation reaction

For successful commercialization of the direct ethanol fuel cell (DEFC), cheaper long-lasting lower noble metal contained anode catalyst is highly needed. For this, nitrogen-doped reduced graphene oxide (N-rGO) supported palladium-nickel alloy nano catalysts with tuned Pd:Ni ratio was synthesized using chemical co-reduction method. Aiming to have better catalytic efficacy and further reduction of cost, nonmetal phosphorus is incorporated to the most active Pd3Ni/N-rGO catalyst to prepare lower Pd contained Pd3NiP/N-rGO ternary catalyst. X-ray diffraction confirms the fcc alloy structure and microscopic study reveals precisely that spherical particles of nano dimension are well distributed on the N-rGO support. XPS analysis confirms the presence of nitrogen and phosphorus along with Pd and Ni in the catalyst matrix. Electrochemical evaluation by cyclic voltametry, chronoamperometry and electrochemical impedance spectroscopy showed that among the bimetallic catalysts studied, Pd3Ni/N-rGO catalyst exhibits synergistic and optimum electro-catalytic performance and poisoning tolerance towards ethanol oxidation reaction (EOR) in the high pH medium. But, phosphorus containing Pd3NiP/N-rGO catalyst shows even more enhanced catalytic performance (2223 mA mg−1Pd current density) than its bimetallic counterpart (1416 mA mg−1Pd current density) signifying that nonmetal phosphorus can effectively promote ethanol oxidation. Moreover, N-doped reduced graphene oxide enhances the catalyst dispersion by creating new active sites, which improves the proper utilization of noble metal Pd. Additionally, the synergistic effect between Pd, Ni and P particles and the support caused by N doping helps to enhance electrocatalytic activity and long-term stability of the catalyst.

Three-Dimensional PdPtCu Nanoalloys with a Controllable Composition and Spiny Surface for the Enhancement of Ethanol Electrocatalytic Properties.

Pt-based nanomaterials have been proven to be effective catalysts for direct alcohol fuel cells (DAFCs). Specifically, the ternary nanoalloys (NAs) composed of Pt with other noble metals and transition metals can not only reduce the component of Pt but also enhance the electrocatalytic property and durability for alcohol oxidation. Herein, ternary PdPtCu NAs were synthesized through the solvothermal method using ethylene glycol as the solvent and reducing agent. The morphology and composition of PdPtCu NAs can be effectively controlled via selecting suitable surfactants and adjusting the proportion of precursors. The three-dimensional (3D) PdPtCu NAs with spiny rambutan-like morphology were obtained using the triblock copolymer Pluronic F-127 (PF-127) as the surfactant and adding three precursors with an equal molar ratio. The unique structure of PdPtCu NAs and the synergistic effect between the components significantly improved the electrocatalytic activity toward ethanol oxidation. Compared with different atomic ratio binary or ternary nanomaterials, 3D PdPtCu NAs manifested the best electrocatalytic performance.

Blue laser-induced photochemical synthesis of CuAg nanoalloys on h-BN supports with enhanced SERS activity for trace-detection of residual pesticides on tomatoes

The copper (Cu)-based nanoalloys loaded on graphene-like nanoplates have a great promise for boosting surface-enhanced Raman scattering spectroscopy (SERS), due to low-cost Cu species in comparison with noble metals and unique additional Raman enhancement originated from two-dimensional (2D) supports. Herein, we report an ingenious strategy to load highly dense and monodisperse CuAg nanoalloys (NAs) on hexagonal boron nitride (h-BN) by blue laser (405 nm) -induced photochemical reaction. Without the aid of any complex auxiliary reagents, the co-reduction of Cu and Ag ions is driven by photon-excited electron on semiconductor h-BN, resulting in the coalescence and overgrowth of “clean” CuAg NAs. As expected, the proposed h-BN/CuAg NAs provide ultrahigh SERS activity with the limit of detections (LODs) of crystal violet (CV) at femtomole level (∼10−16 M), thiram and tricyclazole at picomolar (10−12 M) and nanomolar levels (10−9 M), respectively. Most importantly, the as-prepared h-BN/CuAg NAs were also directly combined with polyethylene terephthalate (PET) by simple dripping and drying processes to form uniform flexible substrates. The low-cost Cu-based flexible substrates can be used to realize the ultrasensitive SERS detection of residual tricyclazole on tomato surfaces, thus facilitating the widespread precise assessment of pesticide residues in various practical applications.

Synthesis and characterization of hypoeutectic Al-Mg nano powder produced by electrical explosion method

Hypoeutectic composition of Al-Mg alloy binary system was established as a stabilized composition for production of Al-Mg alloy nano powders for fabrication of solid propellant. Nano powder of hypoeutectic Al-Mg alloy was prepared by high voltage Electrical Wire Explosion Process (EEW) under inert Argon and Helium gas environment with chamber pressure of 25 kPa and 50 kPa. The thin wires for explosion were prepared by Electrical Discharge Machining (EDM) process from Al-Mg alloy cast. XRD analysis of powder produced and alloy cast was performed to compare the phases present. Scanning Electron Microscope (SEM) images were taken for studying the shape and structure of the nano powder particles and Energy Dispersive Analysis of x-rays (EDX) was performed for affirming elemental composition of alloy powder. Morphological characteristics of nano powders were analyzed by Transmission Electron Microscope (TEM) images and the particle diameter was found ranging from10 nm to 90 nm. Highly magnified TEM images were obtained to analyze the formation of various phases in the powder. Thermo-Gravimetric Analysis and Differential Scanning Calorimetry (TGA-DSC) measurements were made to substantiate the low melting nature of Al-Mg alloys predicted by Al-Mg binary phase diagram with an offset temperature of melting 460 °C, which is much closer to the eutectic melting point (450 °C) of Al-Mg binary metal alloy. With the improved ductility of hypoeutectic alloys enabling better machinability to produce thin wires than eutectic composition, the results suggests hypoeutectic nano powders can be used as replacement for nano aluminium as energetic element in solid propellants.

Exsolution of Nano Metal Particle on Anode for Increased Performance at Low Temperature Operation

Spinel oxide (CuFe2O4) has been studied as anode for solid oxide fuel cells. Although CuFe2O4 spinel structure was decomposed by reduction atmosphere observed by SEM-EDX, TEM-EDX and XRD, the decomposed CuFe2O4 became metallic phase with the exsolved nano size alloy particles, which were composite of Cu rich Cu-Fe and Fe rich Fe-Cu metal on anode. According to power generation properties, alloy anode formed from CuFe2O4 showed the maximum power density (MPD) of 611 mW/cm2 at 1073 K and 101 mW/cm2 at 873 K. Comparing to Ni-Fe (9:1 wt.%) alloy anode, alloy anode from CuFe2O4 reduction showed significantly decreased anodic polarization resistance, which was measured by impedance spectroscope and so high power density was assigned to nano alloy particles.

Nano Alloy Coatings as Bearing Liners—An Experimental Investigation

Nano Alloy Coatings as Bearing Liners—An Experimental Investigation

Geometrical effect in Mg-based metastable nano alloys with BCC structure for hydrogen storage

Mg-based materials are thought to be promising candidates for future hydrogen storage applications due to the low cost, abundant resources and large hydrogen storage capacity. However, they suffer from the challenges of sluggish kinetics and large volume change after hydriding/dehydriding (H/D) process. In order to address the problems, we successfully synthesized the Mg-based Body-Centered Cubic (BCC) metastable nano alloys with much improved kinetics while almost no obvious structure change after H/D process. In this work, the obtained Mg55Co45 metastable alloy with BCC structure can reach a hydrogen storage capacity of 3.24 wt% (hydrogen per metal or H/M = 1.28, H/Mg = 2.33) at −15 °C and this absorption temperature in Mg-based BCC structure is the lowest temperature reported for Mg-based materials to absorb hydrogen. Importantly, the BCC structure is maintained without obvious metal lattice change after H/D process. Nevertheless, the potential uptake of about 20 wt% theoretical hydrogen capacity (H/M = 9) for this unique BCC structure cannot be reached up to now. Herein, we discuss the mechanism from the geometrical effect aspect to figure out the difference between the experimental hydrogen storage capacity (H/M = 1.28) and the theoretical one (H/M = 9).

Cu–Fe–Ni nano alloy particles obtained by exsolution from Cu(Ni)Fe2O4 as active anode for SOFCs

The metal exsolution of anodes was studied using spinel oxides of CuFe2O4 for enhancing the anodic activity of electrodes for solid oxide fuel cells (SOFCs) at lower temperatures.

Laser induced synthesis and concentration dependent thermo-optical properties of silver-gold alloy nanoparticles

Silver and gold nanoparticles were synthesised separately in water by laser ablation method using Nd:YAG nanosecond laser. The synthesized nano solutions, mixed in an equal proportion were again irradiated by the laser to get silver-gold alloy nanoparticles. The formation of alloy nanoparticle was confirmed using UV-Visible spectroscopy. The stability of silver, gold and alloy nano colloidal solutions was established using zeta potential analysis. The structure and size of the formed alloy nanoparticles were investigated using TEM images. Concentration dependant thermal diffusivity changes in silver, gold and silver-gold alloy nano solutions were studied using dual-beam mode matched thermal lens technique. The thermal diffusivity values of the nano fluids were found to increase with the concentration.

Designing of some platinum or palladium-based nanoalloys as effective electrocatalysts for methanol oxidation reaction

Nano alloys contain noble metal nanostructures exhibit a wide theoretical and experimental interest in the field of fuel cells. Hard endeavors have been enhanced to improve the catalytic performance and minimize the usage of precious metals by alloying them with non-precious ones. Formation of bimetallic and trimetallic noble metal alloys with well-designed structures provide the opportunity to reach this goal. In this study, we first discuss the synthesis of noble metal alloy nanostructured thin films such as PtCu, PdCu, PtCu/reduced-graphene oxide (RGO), PdCu/RGO, PtCo, PtCo/RGO, PtPdCu and PtPdCu/RGO via a simple reduction of organometallic precursors including [PtCl2 (cod)] and [PdCl2(cod)], (cod = cis, cis-1,5-cyclooctadiene), in the presence of [Cu(acac)2] and [Co(acac)3] (acac = acetylacetonate) at oil/water interface and room temperature, including nanoparticles and nanosheets. Then the effects of the well-defined nanostructures on the improved electrochemical properties are outlined. Finally, we conclude that these non-precious bi and trimetallic alloy nanostructured thin films have better electrocatalytic performance than Pt monometallic thin films and other Pt nanostructures due to the geometric, electronic and stabilizer effect.

Biological synthesis and characterization of tri- metallic alloy (Au Ag, Sr) nanoparticles and its sensing studies

Crystallized Gold (Au), Silver (Ag), Strontium (Sr) tri-metallic nanometal alloy have been prepared and stabilised using plant extracts of coriander root (Coriandrum sativum) in an aqueous system. Aqueous solutions of Au+, Ag+, Sr+ ions are in 1: 1: 1 ratio of Au–Ag-Sr alloy was treated with a filtered solution of Coriandrum sativum root extract for the formation of Au–Ag-Sr trimetallic alloy nano particles (Au-Ag-Sr NP). Analysis of the feasibility of the biologically synthesized bio-functional core–shell nanometal alloy from plant root extract is particularly noteworthy. The colloidal suspensions obtained were in highly stable condition for 6-8 weeks. The prepared Au-Ag-Sr nanometallic alloy was then checked for the surface Plasmon resonance. The composition, morphology, size and structure of the nanoparticles were determined by Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM). Possible sensing applications of these tri- metallic alloy (Au Ag, Sr) nanoparticles are envisaged.

Exploration of Co-Fe alloy precipitation and electrochemical behavior hysteresis using Lanthanum and Cobalt co-substituted SrFeO3-δ SOFC anode

The in-situ precipitated nano metal particles from perovskites have shown broad interest and wide applications in solid oxide fuel cells (SOFCs) as well as in batteries and catalysts. However, the correlations between the precipitation and SOFC anode performance evolution are still unclear. Herein, equal proportion of La/Sr (A-site) and Co/Fe (B-site) co-substituted La0.5Sr0.5Co0.45Fe0.45Nb0.1O3-δ (LSCFN) perovskite oxide is designed and prepared to investigate the Co-Fe alloy precipitation process and the corresponding electrochemical behavior evolution. After annealing in 3% H2O – 97% H2 at temperature of 750–850 °C the A2B2O5 brownmillerite structure is detected as emerging phase from initial ABO3 perovskite, accompanied with the exsolution of Co1-xFex alloy nano particles. Both the brownmillerite structure in oxide substrate and the Iron content in exsolved Co1-xFex particles show an increase with increasing of reducing temperature and time length. As a result the anode performance hysteresis is observed, showing distinct reduction temperature-dependent and reduction time-dependent electrochemical behaviors. The DC conductivity of the porous LSCFN anode layer shows continuous decrease at 750 °C while both the ohmic and polarization resistances show an increase, suggesting a tight correlation to the anode structure and composition evolution. The proposed strategy to pre-reduce the anode at elevated temperature (800 °C) and then decrease to lower operation temperature (750 °C) is demonstrated to effectively mitigate the Co-Fe nano particles coarsening and could presumably slow down the anode polarization resistance degradation.

Nanoalloy Materials for Chemical Catalysis.

Nanoalloys (NAs), which are distinctly different from bulk alloys or single metals, take on intrinsic features including tunable components and ratios, variable constructions, reconfigurable electronic structures, and optimizable performances, which endow NAs with fascinating prospects in the catalysis field. Here, the focus is on NA materials for chemical catalysis (except photocatalysis or electrocatalysis). In terms of composition, NA systems are divided into three groups, noble metal, base metal, and noble/base metal mixed NAs. Their design and fabrication for the optimization of catalytic performance are systematically summarized. Additionally, the correlations between the composition/structure and catalytic properties are also mentioned. Lastly, the challenges faced in current research are discussed, and further pathways toward their development are suggested.

Performance of Supported Au-Pd Alloy Nano Particles Catalyst for Base-free Synthesis of Imines by Self-coupling of Amine

Abstract A series of supported nano particles catalysts, Au/γ-Al2O3, Pd/γ-Al2O3 and Au-Pd/γ-Al2O3, were prepared by the impregnation reduction method. The catalytic performance of these catalysts for direct base-free synthesis of imines by self-coupling of benzylamine was investigated. The results show that the yield of imine could reaches 93% over bimetallic alloy Au-Pd/γ-Al2O3 catalyst, much higher than monometallic Au or Pd nano particle catalyst. The used catalyst is recovered and 44% yield of imine could be obtained after 5 recycling use of Au-Pd/γ-Al2O3.

Enhanced and Synergistic Catalysis of Green Synthesized Pd-Ag Alloy Nanoparticles for Anodic Oxidation of Propan-2-ol in Alkali

Bimetallic PdxAgy alloy along with monometallic Pd, Ag nanoparticle were synthesized in a single pot using a green synthetic protocol in absence of any capping agent. X-ray diffraction and microscopic studies of synthesized material demonstrate the formation of nanoballs with radius of ca 25 nm of face centred cubic metals and alloys. The electrochemical studies of as-synthesized materials loaded on carbon support reveal that the Pd4Ag nanoparticles exhibit the best and synergistic electro-catalytic activity in reference to oxidation of propan-2-ol in alkali. The most active Pd4Ag nanoparticles show higher peak current (124.54mAmg-1) in comparison to that (92.54mAmg-1) of Pd in cyclic voltammetric study (CV). The electrode shows the highest exchange current density (0.284mAmg-1of Pd) for propan-2-ol oxidation reaction. CV studies of reaction product reveal that Ag accelerates the formation of acetone rather than carbonate elucidating the plausible mechanism of the reaction. These findings have important implications for further fine-tuning of the Pd nano alloys toward highly active and selective catalysts for alcohol fuel cells.

Multi-metal nanomaterials obtained from oil/water interface as effective catalysts in reduction of 4-nitrophenol

In this study Pt and Pd-based nanostructured thin films have been successfully fabricated by room temperature self-assembly of metal nanoparticles (NPs) at the interface between toluene and water without/with using stabilizers such as graphene oxide (GO) or aminoclay (AC). Successful formation of these thin films is investigated by transmission electron microscopy (TEM), energy dispersive analysis of X-ray (EDAX) and X-ray diffraction (XRD). Catalytic hydrogenation of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) was investigated using thin film nanocatalysts. The as synthesized nanostructured thin films exhibit high catalytic activity toward hydrogenation reaction of 4-NP. This study highlights the value of nano alloy thin films and their ability as catalyst in catalytic hydrogenation reaction.

Mechanically prelithiated silicon nano alloy as highly engineered anode material

Silicon (Si) anodes suffer from huge volume changes leading to cracking and pulverization impacting the battery life. To deliver high energy and long-term stability, we present a unique and facile prelithiated silicon nano alloy (SiNA) material with lithium stearate as reagent. Structurally controlled SiNA (in this work Si -iron (Fe)-manganese (Mn) combination) design with active Si surrounded by inactive buffer matrix to reduce mechanical deterioration during expansions was synthesized using a low-cost and low-temperature process relying on mechanical milling. Prelithiation was accomplished to compensate for the initial irreversible loss by pre-feeding with the lithium reagent to form a protective artificial solid electrolyte interphase (SEI) and prefill the mechanical crack voids of the SiNA to improve the mechanical properties necessary for long-term cyclability. The approach was to mechanically mix SiNA with lithium stearate followed by heat treatment above the melting point of lithium stearate to allow its easy diffusion with the surface and mechanical voids of the SiNA. Prelithiated SiNA exhibited enhanced physicochemical properties and featured boosted mechanical integrity characterized by nanoindentation. In overall, prelithiated SiNA revealed excellent electrochemical properties and long-term cycling stability addressed at significantly high loading (∼2 mg cm−2) and over 250 cycles, demonstrating its transformable potential to high energy applications.