Bimetallic Alloy Nanoparticles Research Articles

Synthesis of Au@Pt nanoparticles for detection of ascorbic acid

Nanoenzyme is a kind of mimic enzyme with unique properties of nanomaterials and catalytic function. They have been developed to address the limitations of natural enzymes and conventional artificial enzymes. Compared with traditional mimic enzymes, nanoenzymes have the advantages of higher catalytic efficiency, low costs, high stability against stringent reaction conditions. The catalytic reaction of nanoenzymes is the same as natural enzymes, which depends on pH, temperature and substrate concentration. Taking advantage of the high catalytic properties of bimetallic alloy nanoparticles, we prepare Au@Pt nanoparticles with high catalytic activity and use it to detect ascorbic acid. As a mimic oxidase, Au@Pt nanoparticles shows the good biocompatibility of Au@Pt nanoparticles for promising bioapplications[1].

Non-enzymatic electrochemical detection of glucose using Ni-Cu bimetallic alloy nanoparticles loaded on reduced graphene oxide through a one-step synthesis strategy.

In this work, Ni-Cu bimetallic alloy nanoparticles supported on reduced graphene oxide (Ni-Cu ANPs/RGO) was successfully fabricated through a one-step hydrothermal synthesis method, where simultaneous reduction of graphene oxide, nickel salt and copper salt was performed, and relevant characterization studies were executed. This synthetic method does not require surfactants and high temperature treatment, and is recommended as a green, convenient and effective way to produce composites. The unique two-dimensional architecture of the RGO provides a large specific surface area, contributing to loading more Ni-Cu ANPs, while the uniformly distributed Ni-Cu bimetallic alloy nanoparticles enhance the electrocatalytic performance of glucose oxidation. The non-enzymatic glucose biosensor based on Ni-Cu ANPs/RGO showed a wide linear range (from 0.01 μM to 30 μM), low detection limit (0.005 μM), and excellent sensitivity (1754.72 μA mM-1 cm-2). More importantly, the high reliability and the excellent selectivity in actual sample detection will broaden its practical application in electrochemical sensing.

Antibacterial and Immunomodulatory Potentials of Biosynthesized Ag, Au, Ag-Au Bimetallic Alloy Nanoparticles Using the Asparagus racemosus Root Extract.

Two noble metals, such as silver and gold alloy nanoparticles, were successfully synthesized by the microwave assisted method in the presence of the Asparagus racemosus root extract and were used as an antibacterial and immunomodulatory agent. The nanostuctures of the synthesized nanoparticles were confirmed by various spectroscopic and microscopic techniques. The UV-vis spectrum exhibits a distinct absorption peak at 483 nm for the bimetallic alloy nanoparticles. The microscopic analysis revealed the spherical shaped morphology of the biosynthesized nanoparticles with a particle size of 10–50 nm. The antibacterial potential of the green synthesized single metal (AgNPs and AuNPs) and bimetallic alloy nanoparticles was tested against five bacterial strains. The bimetallic alloy nanoparticles displayed the highest zone of inhibition against P. aeurgnosia and S.aureus strains when compared to single metal nanoparticles and plant extract. In addition, the inmmunomodulatory potential of the root extract of A. racemosus, AgNPs, AuNPs, and Ag-Au alloy NPs is achieved by measuring the cytokine levels in macrophages (IL-1β, IL-6, and TNF-α) and NK cells (IFN-γ) of NK92 and THP1 cells using the solid phase sandwich ELISA technique. The results showed that the root extract of A. racemosus, AgNPs, and AuNPs can reduce the pro-inflammatory cytokine levels in the macrophages cells, while Ag-Au alloy NPs can reduce cytokine responses in NK92 cells. Overall, this study shows that the microwave assisted biogenic synthesized bimetallic nanoalloy nanoparticles could be further explored for the development of antibacterial and anti-inflammatory therapies.

Nickel Nanocatalysis: An Efficient Tool for Heck Reaction

AbstractOf late, developing non‐precious catalytic protocol with high performance is of primary significance and furnishes fascinating sets of results for synthetic chemists. This minireview describes the advances and scopes of nickel nanoparticles being employed as catalysts in Heck cross‐coupling reactions of aryl halides and olefins in 21stcentury. We have focused on the methods of preparation of nanocatalysts and emphasized on different techniques employed in the generation of nickel nanoparticles or bimetallic alloy nanoparticles.

Continuous flow reduction of organic dyes over Pd-Fe alloy based fibrous catalyst in a fixed-bed system

Continuous flow chemistry has been considered as a green technology for modern catalytic industry as it not only improves the manufacture efficiency but also facilitates the sustainability. Herein we report a facile method for synthesizing bimetallic Pd-Fe alloy nanoparticles catalysts anchored on N doped carbon (NC) functionalized fibrous aluminium silicate fibers (ASFs). The as-prepared ASF@NC/PdFe catalytic fibers are packed into a column to construct a fixed-bed system, which exhibits excellent treatment capacity and durability for continuous catalytic hydrogenation of organic dyes. Typically, the flow rate of the fixed-bed is high up to 200 mL/min for 4-nitrophenol and methylene blue reduction, which is one of the most efficient fixed-bed catalytic systems. The catalytic turnover frequency is calculated to be as high as 59.6 min−1 due to the enhanced synergetic effect of Pd and Fe. Furthermore, only slight loss of activity for the fixed-bed is observed even after nine successive catalytic cycles.

Tunable optical properties of Ni–Ag and Ni–Au nanoparticles in magneto-plasmonic nanostructures

The combined optical and magnetic properties of magneto-plasmonic nanoparticles makes them ideal candidates for various applications in biomedical fields. In the present work, the optical properties of Ni–Ag and Ni–Au bimetallic alloy nanoparticles with varying sizes 20, 30, 40, 50, and 60 nm of spherical and aspect ratio 2, 3, and 4 of non-spherical nanostructures are studied by the discrete dipole approximation method in the water surrounding medium. Moreover, optical absorption spectra are studied to see the effect of polarization and different alloy compositions. The optical spectra is observed in the range of 371–1280 nm wavelengths and merged in visible-near-infrared region on the electromagnetic spectrum. The result shows that absorption spectra of bimetallic alloy nanoparticles can be well tuned by changing the particle size, aspect ratio’s, shapes, and compositions. Furthermore, Ni–Au nanoparticles have enrich optical absorption spectra as compared to Ni–Ag bimetallic nanoparticles. Our study provides a way to analyze and broaden the applications of bimetallic alloy nanoparticles in optical imaging, biomedical field, and therapeutics.

Ag–Pd Alloy Immobilized on Semi-heterogeneous Support as a Novel Highly Efficient Artificial Nitroreductase: Experimental Design Optimization and Kinetic Study

The bimetallic nanocatalysts with improved catalytic activity and selectivity has emerged as an important class of nanocatalysts. Herein, a highly efficient Ag–Pd alloy-based semi heterogeneous magnetic nanocatalyst has been developed. The catalyst exhibits enzyme-like catalytic efficiency for the reduction of nitro functional group of 4-nitro phenol as water contaminant by NaBH4 even at ambient temperature. Exceptionally high turnover frequency, very short reaction time, simple recovery and reusability of catalyst and complete conversion of p-nitrophenol are some remarkable features of this semi heterogeneous nanocatalyst. The enzyme-like efficiency of developed nanocatalyst could be related to its architectural configuration, the catalytic performance of Ag–Pd bimetallic alloy nanoparticles and organophilic microenvironment which raised from semi heterogeneous nature of support. Moreover, the design of experiments methodology was employed to optimize the reaction conditions and the kinetic study was carried out to explore enzyme-like activity of designed catalyst. A novel Ag–Pd alloy-based semi heterogeneous magnetic nanocatalyst represented superior catalytic activity and selectivity for the reduction of p-nitrophenol in water even at room temperature.

Electrocatalytic efficacy of Ni-Cu@VC-72: Non-enzymatic electrochemical detection of glucose using Ni-Cu nanoparticles loaded on carbon black

Ni-Cu bimetallic alloy nanoparticles supported on Vulcan carbon (VC) were proved to be the convenient and effective electrochemical glucose sensor owing to its high surface area and large active sites. The Ni-Cu bimetallic NPs loaded on VC were successfully prepared by the chemical reduction method. Morphology and structure of the prepared nanoparticles were characterized using scanning electron microscope (SEM) and X-ray diffraction (XRD). Elemental analysis of the prepared nanoparticles was carried by using Energy-dispersive X-ray (EDX) spectroscopy. It was observed that glassy carbon electrode (GCE) modified with Ni-Cu@VC showed high electro-catalytic activity toward the oxidation of glucose. The electrochemical characterization was done by using cyclic voltammetry (CV) and amperometry. Effects of endogenous interfering species (ascorbic acid, uric acid, acetaminophen, and NaCl) on the electrocatalytic response of Ni-Cu@VC/GCE were also studied, which showed that Ni-Cu@VC NPs are selective electrocatalyst towards glucose oxidation. The Ni-Cu@VC/GCE showed high stability, reproducibility and high sensitivity (1515 μA mM−1 cm−1) towards glucose oxidation. The limit of detection (LOD) was calculated to be 4 μM while the limit of quantification (LOQ) was found to be 14 μM, respectively.

Low-temperature oxidation of carbon monoxide over Bi-metallic nanoparticles incorporated three dimensional silica

In the current study, four new catalysts were synthetized by using TUD-1 mesoporous material as a support for bi-metallic Noble metals nanoparticles. M-Au-TUD-1 (M = Rh, Pd, Pt, and Ag) were prepared with a total metals loading of 2 wt% by applying the ratio of 1Au:1M. Several physical and chemical characterizations were performed to understand the structure of the prepared catalysts. The characterization results showed the formation of bi-metallic alloys between Au and Pd, Rh or Ag, while the formation of alloy between Au and Pt was not confirmed under the applied synthesis conditions. The formed bi-metallic alloy nanoparticles were found to be highly distributed through the mesoporous silica and the average size of the formed nanoparticles was 15–30 nm. The prepared samples were investigated to catalyze the environmentally impacted reaction of carbon monooxide (CO) oxidation to carbon dioxide (CO2). The catalytic efficiency of Ag–Au catalyst was higher than the other investigated catalysts, 100% of CO gas was converted over Ag–Au catalyst at 25 °C. Moreover, Pt–Au and Pd–Au catalysts exhibited similar activity to bare Au nanoparticles. Moreover, the stability of the four investigated catalysts was investigated by using the same catalytic sample in ten consecutive reactions without treatment, Rh–Au-TUD-1 and Pt–Au-TUD-1 exhibited the highest stability, while, Ag–Au showed partial deactivation due to the oxidation of Ag to Ag2O.

Bimetallic MnCo alloy nanoparticles decorated boron-doped carbon nanotubes as an active and durable electrode for supercapacitor

Abstract The demand for low-cost and high-performance energy storage supercapacitors is continuously promoting as a result of the rapid development of portable electric vehicles and electronic devices. Here, a high-performance MnCo alloy nanoparticles decorated boron-doped carbon nanotubes (MnCo–B/CNTs) electrode was obtained by a facile heteroatom hydrothermal and subsequent liquid-phase reduction methods, which yields improved performance for supercapacitor. In this process, boron doping led to extra oxygen graft into carbon surface, leading to the improved durability and wettability of the fabricated carbon-based electrodes, which presented both increased capacitances and rate capability due to electrolyte ion penetration and interactions with carbon surface. In addition, boron doping led to smaller size and higher dispersion of MnCo nanoparticles, facilitating more metallic alloy and new electroactive sites formation and promoting supercapacitive activity, which was attributed to increased MnCo alloy nucleation rate with boron-doped, electron donation from boron to alloy, and extra chemisorption sites. The constructed electrode exhibited all-round performance improvements of specific capacitance (1175 F g−1 at 0.5 A g−1) and capacitance retention (94.48% at a current density of 20 A g−1 after 5000 cycles), providing a novel insight for designing high performance supercapacitors.

Monitoring of Anthracene Using Nanoscale Au-Cu Bimetallic Alloy Nanoparticles Synthesized with Various Compositions.

Bimetallic alloy Au–Cu nanoparticles (Au–Cu alloy NPs) were synthesized using a chemical reduction method for sensing applications. Electronic absorption spectroscopy (UV–visible spectroscopy), X-ray diffraction (XRD), and scanning electron microscopy (SEM) were used for the confirmation and morphological studies of the synthesized nanoparticles. The composition of Au–Cu alloy NPs was studied by energy-dispersive spectroscopy (EDS). The high crystallinity of Au–Cu alloy NPs was demonstrated by XRD analysis. Both XRD and SEM analyses revealed that the nanoparticles’ size ranges from 15 to 25 nm. Pyrrole was polymerized into polypyrrole (PPy) over a neat and clean glassy carbon electrode (GCE) by potentiodynamic polymerization. The sensitivity of GCE was improved by modifying it into a composite electrode. The composite electrode was developed by coating GCE with an overoxidized PPy polymer followed by Au–Cu alloy NPs. The ratio of Au and Cu was carefully controlled. The composite electrode (PPyox/Au–Cu/GCE) successfully detected an environmental toxin anthracene with a detection limit of 0.15 μM, as evidenced by cyclic voltammetry (CV), square-wave voltammetry (SWV), and electrochemical impedance spectroscopy (EIS).

Freestanding electrospun carbon nanofibers uniformly decorated with bimetallic alloy nanoparticles as supercapacitor electrode

• CoNi-alloy nanoparticles embedded in CNF electrodes were produced. • High specific capacitance of 132 Fg −1 at 1Ag −1 with high capacitance retention of 85.3% up to 10,000 cycles was achieved. • High specific energy of 4.60 Whkg −1 at the specific power of 250 Wkg −1 was observed. In this paper, we proposed that CoNi-alloy nanoparticles (NPs) can be directly encapsulated carbon nanofibers (CNFs) via electrospinning process followed by heat treatment. By adjusting the concentration of the Co/Ni metallic salts, the electrochemical properties of the resultant nanofibers can easily be tuned. CoNi-alloy NPs embedded in CNF resulted in 1.4 times electrochemical performance compared to the pure CNF. The assembled symmetric supercapacitor (SC) shows a high a specific capacitance of 132 Fg −1 at 1 Ag −1 and it can deliver a specific energy of 4.60 Whkg −1 with a specific power of 250 Wkg −1 with 85.3% capacitance retention up to 10,000 cycles. This work can provide a key strategy for a rapid design of bimetallic alloy nanoparticles directly from their salts in carbon nanofiber for various applications.

Bimetallic iron-iridium alloy nanoparticles supported on nickel foam as highly efficient and stable catalyst for overall water splitting at large current density

In this work, FeIr bimetallic alloy self-supported on nickel foam is prepared by hydrothermal method, with average particle size of 2.17 nm and the Ir-loading is only 0.936 wt.%. It displays ultralow overpotentials for OER (200 mV) and HER (16.6 mV) at 20 mA cm−2 in alkaline media, which is superior to the ever reported HER catalysts. For overall water splitting, it only needs 1.48 V to derive a current density of 10 mA cm−2, and it also demonstrates an outstanding long-term stability with an ignorable decline in performance after testing 504 h at the current density of 150 mA cm−2. The excellent performance is ascribed to the ultrasmall FeIr alloy, the 3D conductive substrate, and the ethylene-glycol ligand environment facilitates highly efficient HER through hydrogen spillover. Thus, this work undoubtedly provides a promising method for developing ultralow-loading noble metal catalysts with excellent performance at large current density for overall water splitting.

Thermal conversion of hollow nickel-organic framework into bimetallic FeNi3 alloy embedded in carbon materials as efficient oer electrocatalyst

Rapid deployment of renewable energy causes a significant change in environmental benefits. Thus, the transition metal-based electrocatalysts are developed to achieve efficient water splitting. Here a simple three-step method is adopted to successfully synthesize a type of hollow MOF-derived three-dimensional carbonaceous matrix that is randomly loaded with numerous FeNi3 alloy nanoparticles (NiFeC). In this work, the as-obtained NiFeC-800–5(carbonization temperature: 800 °C; pyrolysis rate: 5 °C/min) shows an excellent oxygen evolution reaction catalytic activity in 1.0 M KOH electrolyte, with a low overpotential of 269 mV at 10 mA cm-2 and a low Tafel slope of 72 mV dec‑1. Moreover, it exhibits an ultrastable durability after being electrolyzed continuously for 10 h, which is originated from these fine alloys encapsulated into the hierarchically porous carbonaceous material. Finally, we have proposed morphological and chemical changes for the NiFeC-800–5sample, in which the solid MOF precursor will be gradually etched into the hollow morphology by the strong hydrolysis of Fe(III) ions at high temperature, and the optimal carbonization temperature and heating rate are also well investigated. Moreover, the above approach can be used to obtain other MOF derived bimetallic alloy nanoparticles encapsulated into carbon materials for the energy conversion and storage applications.

Medium-Pressure Reactivity of Acetylene on Pd-Cu Alloy Nanoparticles Supported on Thin Silica Films.

The ability to correlate industrial high-pressure catalysis with high-vacuum research has been of great interest for decades. We employed a double-chamber vacuum system to study the self-hydrogenation of acetylene to ethylene and its trimerization to benzene at medium pressures to compare the reactivity in this pressure range to the known model catalytic acetylene reactivity in ultrahigh vacuum (UHV). We measured the reactivity of Pd-Cu bimetallic alloy nanoparticles (ANPs) with different elemental compositions deposited on top of native SiO2/Si(100) and on bilayer SiO2/Ru(0001) surfaces, where the latter was shown to contribute to ANP stability. Following exposure to 0.5 mbar of acetylene, ANPs on both surfaces catalyze the formation of ethylene and benzene, with ethylene as the more probable product. The ANPs on bilayer SiO2/Ru(0001) were highly selective toward ethylene formation, with an ethylene/benzene ratio of more than 2 orders of magnitude, whereas on the native SiO2/Si(100) there was a significantly lower selectivity (about 5) at the same temperature range and catalyst elemental composition. Interestingly, these selectivity values are similar to those found under UHV conditions. In addition, ANPs grown on native SiO2/Si(100), unlike SiO2/Ru(0001), revealed an optimal temperature for ethylene and benzene formation due to the limited stability of the particles.

Study on preparation and performance of Ru-Fe/GO catalyst for sodium borohydride alcoholysis to produce hydrogen

Ru-Fe bimetallic alloy nanoparticle catalyst (Ru-Fe/GO) was prepared by chemical reduction method on graphene oxide prepared using Hummers modified method. The structure and morphology of both GO and Ru-Fe/GO were analyzed using X-ray diffraction (XRD), Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS).The effect of catalyst components on hydrogen generation rate for NaBH4 methanolysis was investigated. When Ru:Fe is 6:1, the catalytic activity is the highest, and the average rate is about 473 mL·min−1·g−1. The effect of temperature, Sodium hydroxide concentration, and sodium borohydride concentration on reaction rate is also discussed, and the activation energy for the methanolysis of sodium borohydride is 59.33 kJ·mol−1 based on the data.

Effect of morphology and role of conductivity of embedded metallic nanoparticles on electromagnetic interference shielding of PVDF-carbonaceous-nanofiller composites

In this work, EMI shielding behaviors in the X-band frequency have been investigated for flexible polyvinylidene fluoride (PVDF) composites containing globular- and tubular-shaped carbonaceous nanostructures embedded with mono-metallic (Ni) and bi-metallic (FeNi, CoNi, MnNi) alloy nanoparticles. Pyrolysis was carried out at two different temperatures (800 °C and 1000 °C) to synthesize carbonaceous materials with two different morphologies. Carbon nanotubes (CNTs) are predominantly seen in the samples synthesized at lower temperature (800 °C), whereas carbon globules (CGs) are observed for the samples synthesized at higher temperature (1000 °C). The PVDF-CNT composites show superior microwave shielding behavior than the PVDF-CG composites, which is attributed to the enhanced absorption of the microwave through Ohmic conduction and interfacial polarization loss. The 1-D structure of CNTs provides the required conduction path for the electrons and forms a network to trap the microwave within them via multiple scattering. The microwave absorption behavior of the composites predominantly results from the metallic nature of the embedded nanoparticles, the graphitic layer encapsulating them and the graphitic walls of the CNTs. We further demonstrate the direct correlation of the EMI shielding behavior of the nanocomposites with the morphology of carbonaceous nanomaterials and the conductivity of the embedded metallic nanoparticles.

Development of nitrogen doped carbon dots modified CuCo alloy nanoparticles for potential electrocatalytic water splitting

Water splitting in recent years has been emerged as a promising approach for renewable energy sources. A number of materials have been synthesized for successful electrosplitting of water. Yet, the simultaneous production of hydrogen and oxygen with the help of efficient and stable bi-functional electrocatalyst is still challenging. Correspondingly, the precious metal based catalysts are gaining much interest for the efficient inexpensive and ecofriendlier practical application in energy materials among researchers. Herein, we report new combination of nitrogen doped carbon dots modified copper cobalt (NDCDs-CuCo) alloy nanoparticles as potential electrocatalyst for water splitting. These catalysts were synthesized at different temperatures. The NDCDs-CuCo alloy nanoparticles exhibit excellent catalytic performances and stability in alkaline medium for hydrogen and oxygen evolution reactions (HER and OER) through synergistic effect between nitrogen doped carbon dots and bimetallic CuCo alloy nanoparticles at optimized conditions of onset over potentials and current densities. NDCDs-CuCo alloy nanoparticles possess electrocatalytic properties in strong alkaline medium with current density of 10 mA cm−2 at 0.38 V.

Laser-induced metastable mixed phase of AuNi nanoparticles: a coherent X-ray diffraction imaging study.

The laser annealing process for AuNi nanoparticles has been visualized using coherent X-ray diffraction imaging (CXDI). AuNi bimetallic alloy nanoparticles, originally phase separated due to the miscibility gap, transform to metastable mixed alloy particles with rounded surface as they are irradiated by laser pulses. A three-dimensional CXDI shows that the internal part of the AuNi particles is in the mixed phase with preferred compositions at ∼29 at% of Au and ∼90 at% of Au.

Chemically Ordered Pt–Co–Cu/C as Excellent Electrochemical Catalyst for Oxygen Reduction Reaction

This paper reveals the ordered structure and composition effect to electrochemical catalytic activity towards oxygen reduction reaction (ORR) of ternary metallic Pt–Co–Cu/C catalysts. Bimetallic Pt-Co alloy nanoparticles (NPs) represent an emerging class of electrocatalysts for ORR, but practical applications, e.g. in fuel cells, have been hindered by low catalytic performances owning to crystal phase and atomic composition. Cu is introduced into Pt-Co/C lattices to form PtCoxCu1−x/C (x = 0.25, 0.5 and 0.75) ternary-face-centered tetragonal (fct) ordered ternary metallic NPs. The chemically ordered Pt–Co–Cu/C catalysts exhibit excellent performance of 1.31 A mg−1Pt in mass activity and 0.59 A cm−2Pt in specific activity which are significantly higher than Pt-Co/C and commercial Johnson Matthey (JM) Pt/C catalysts, because of the ordered crystal phase and composition control modified the Pt-Pt atoms distance and the surface electronic properties. The presence of Cu improves the surface electronic structure, as well as enhances the stability of catalysts.