Bimetallic Alloy Nanoparticles Research Articles

Synergistic effects of bimetallic Pd-Au(alloy)/SnO2 nanocomposites for low temperature and selective hydrogen gas sensors

In view of the explosive nature of hydrogen gas, the demand for detection is increasing. Although Pd-based chemiresistive sensors are gaining much attention in hydrogen detection, it is easily oxidized at high temperatures, leading to the deterioration of sensing performance. To address this issue, we synthesized bimetallic Pd-Au alloy nanoparticles (NPs) and mixed them with SnO2 powder for improving the hydrogen sensing performance. The response of the bimetallic Pd-Au(alloy)/SnO2 nanocomposites (NCs) sensor toward 100 ppm hydrogen was 72.78 which is 7 times higher than that of the pure SnO2 sensor at a relatively lower working temperature of 150°C. Furthermore, when compared to other interfering gases, the sensor revealed high selectivity for hydrogen gas. The enhanced hydrogen sensing performance was attributed to the synergistic effect arising from the formation of a heterojunction interface between Pd-Au alloy and SnO2 NPs and the decomposition and absorption of hydrogen molecules by Pd-Au alloy NPs.

Silver-Gold Alloy Nanoparticles (AgAu NPs): Photochemical Synthesis of Novel Biocompatible, Bimetallic Alloy Nanoparticles and Study of Their In Vitro Peroxidase Nanozyme Activity.

Facile synthesis of metal nanoparticles with controlled physicochemical properties using environment-friendly reagents can open new avenues in biomedical applications. Nanomaterials with controlled physicochemical properties have opened new prospects for a variety of applications. In the present study, we report a single-step photochemical synthesis of ~5 nm-sized silver (Ag) and gold (Au) nanoparticles (NPs), and Ag-Au alloy nanoparticles using L-tyrosine. The physicochemical and surface properties of both monometallic and bimetallic NPs were investigated by analytical, spectroscopic, and microscopic techniques. Our results also displayed an interaction between L-tyrosine and surface atoms that leads to the formation of AgAu NPs by preventing the growth and aggregation of the NPs. This method efficiently produced monodispersed NPs, with a narrow-sized distribution and good stability in an aqueous solution. The cytotoxicity assessment performed on breast cancer cell lines (MCF-7) revealed that the biofriendly L-tyrosine-capped AgNPs, AuNPs, and bimetallic AgAu NPs were biocompatible. Interestingly, AgAu NPs have also unveiled controlled cytotoxicity, cell viability, and in vitro peroxidase nanozyme activity reliant on metal composition and surface coating.

Exsolution Synthesis of Alloyed Nanoparticles from Perovskite Oxide by Plasma

Bimetallic alloy nanoparticles (NPs) exsolved on the surface of perovskite oxides (ABO3) alter the structural and electronic properties of the primarily monometallic counterparts. These synergistic effects make the whole material present superior electrolytic and catalytic performances. The strong bonding interaction between alloy NPs and perovskite substrate enables the stability and durability of the catalysis.However, traditional thermal exsolution requires a long-time treatment at a high temperature. Researchers have been pursuing more time-saving and energy-efficient alternative routes. Herein, a low-temperature and fast pathway based on the dielectric barrier discharge (DBD) reactor is provided to in-situ exsolve alloy NPs. A favorable activity of the catalyst for CO oxidation is demonstrated. Additionally, we conclude that the factor restricts metallic agglomeration is the morphology of the substrate. Even after an overtime plasma treatment, the exsolved alloy NPs are still embedded in the porous structure of perovskite oxides.

Waste plastics derived nickel-palladium alloy filled carbon nanotubes for hydrogen evolution reaction

Carbon nanotubes (CNTs) composed of bimetallic nickel-palladium (NiPd) nanoparticles encapsulated in graphitic carbon shells (NdPd@CNT) are prepared by the chemical vapour deposition method using waste polyethylene terephthalate (PET) plastic carbon sources and NiPd-decorated carbon sheets (NiPd@C) catalyst. The characterization results reveal that the face-centered cubic crystalline (fcc)-structured NiPd bimetallic alloy nanoparticles are encased by thin carbon nanotubes. The bimetallic synergism of NiPd nanoparticles actuates the outer CNT layers and accelerates the electrical conductivity, stimulating the electrochemical activity toward an effective hydrogen evolution reaction (HER). By virtue of the collective individualities of highly conductive aligned carbon walls and bimetallic active sites, the NiPd@CNT-equipped HER delivers a minimum overpotential of 87 mV and a Tafel slope value of 95 mV dec−1. The existing intact contact between NiPd and CNT facilitates continuous electron and ion transportation and firm stability toward long-term hydrogen production in HER. Notably, the NiPd@CNT reported here produces excellent electrochemical activity with minimal charge transference resistance, substantiating the efficacy of NiPd@CNT for futuristic green hydrogen production.

Green synthesis of bimetallic Pd[sbnd]Ag alloy nanoparticles supported on polydopamine-functionalized kaolin for catalytic reduction of 4-nitrophenol and organic dyes

A green and universal synthesis strategy was demonstrated for preparation of bimetallic PdAg alloy nanoparticles supported on polydopamine-functionalized kaolin (kaolin-PDA-PdAg), where bimetallic PdAg alloy was synthesized by co-reduction of Na2PdCl4 and AgNO3 with sodium citrate. Characterization results, including TEM results and XPS results, confirmed that bimetallic PdAg was alloying state and kaolin-PDA-PdAg was successfully synthesized through mussel-inspired chemistry. The kaolin-PDA-PdAg nanocomposite exhibited excellent catalytic activity and performance towards reduction of 4-nitrophenol, whose rate constant was found to be 3.46 min−1 under condition of high concentration (10 mM) of 4-nitrophenol. Besides, kaolin-PDA-PdAg nanocomposite showed high catalytic performance for methyl orange and safranine-T as well. The high catalytic activity of kaolin-PDA-PdAg could be elucidated by electronic effect and synergistic effect of bimetallic PdAg alloy. These results suggest that kaolin-PDA-PdAg composites could be applied as high-efficiency catalysts for reduction of 4-nitrophenol and degradation of organic dyes. Furthermore, abundance and low-priced of raw materials kaolin, green and versatility of synthetic method endow kaolin-PDA-PdAg composites with broad application prospects. Strategy of bimetallic PdAg alloy anchored on kaolin in this text could provide an efficient platform for synthesis of bimetallic alloy nanoparticles loaded on various materials.

Bimetallic NiCu alloy nanoparticles supported on porous carbon nanosheets as an efficient electrocatalyst for methanol and urea electrooxidation

Bimetallic NiCu alloy nanoparticles supported on porous carbon nanosheets as an efficient electrocatalyst for methanol and urea electrooxidation

Bimetallic Ag-Pd nanoparticles decorated ZnO nanorods for efficient hydrogen sensing

The current study aims to understand the interactions between the gaseous species with zinc oxide surface in the presence of bimetallic alloy Ag-Pd nanoparticles. To achieve this goal, we have synthesized well-known nanorod-like structures of ZnO via the facile hydrothermal route and further decorated these structures with several combinations of Ag-Pd bimetallic alloy nanoparticles. The fabricated samples proceeded to characterizations with X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy to evaluate and validate the morphological and structural parameters and elemental constituents. Finally, the synthesized materials were deployed to the interdigitated electrodes to fabricate the gas sensor devices. And the gas sensor devices were tested for various gases to investigate the interaction of gases with the material employing resistance change. The sensor with a 1:1 Ag:Pd/ZnO sample has shown the highest selective response of 51.36 at 275 °C temperature towards 100 ppm of H2 gas. Finally, a possible mechanism of interaction is also discussed.

Synthesis of Bimetallic Silver and Copper Alloy Nanoparticles Embedded with Styrene-Methyl Methacrylate Copolymer Nanosphere (SMMA@Ag-Cu) as a Potential Surface Enhanced Raman Scattering (SERS) Substrate

Synthesis of Bimetallic Silver and Copper Alloy Nanoparticles Embedded with Styrene-Methyl Methacrylate Copolymer Nanosphere (SMMA@Ag-Cu) as a Potential Surface Enhanced Raman Scattering (SERS) Substrate

Bimetallic Nanoalloy Catalysts for Green Energy Production: Advances in Synthesis Routes and Characterization Techniques.

Bimetallic Nanoalloy catalysts have diverse uses in clean energy, sensing, catalysis, biomedicine, and energy storage, with some supported and unsupported catalysts. Conventional synthetic methods for producing bimetallic alloy nanoparticles often produce unalloyed and bulky particles that do not exhibit desired characteristics. Alloys, when prepared with advanced nanoscale methods, give higher surface area, activity, and selectivity than individual metals due to changes in their electronic properties and reduced size. This review demonstrates the synthesis methods and principles to produce and characterize highly dispersed, well-alloyed bimetallic nanoalloy particles in relatively simple, effective, and generalized approaches and the overall existence of conventional synthetic methods with modifications to prepare bimetallic alloy catalysts. The basic concepts and mechanistic understanding are represented with purposely selected examples. Herein, the enthralling properties with widespread applications of nanoalloy catalysts in heterogeneous catalysis are also presented, especially for Hydrogen Evolution Reaction (HER), Oxidation Reduction Reaction (ORR), Oxygen Evolution Reaction (OER), and alcohol oxidation with a particular focus on Pt and Pd-based bimetallic nanoalloys and their numerous fields of applications. The high entropy alloy is described as a complicated subject with an emphasis on laser-based green synthesis of nanoparticles and, in conclusion, the forecasts and contemporary challenges for the controlled synthesis of nanoalloys are addressed.

Quantifying the optical and thermoplasmonic properties of some bimetallic alloy nanospheres

The bimetallic alloy NPs are ideal objects for a variety of applications like catalysis, nanofluidics, thermo-voltaic and bio-imaging due to their peculiar and adaptable optical response in UV–visible-NIR region of optical spectra. The heating effect of bimetallic alloys involves surface plasmon resonance (SPR) and takes place when the material is illuminated by light. Instead of pure and alloy NPs of Au & Ag, the opto-thermal properties of Au-Cu, Au-Al, Ag-Cu and Ag-Al bimetallic alloy nanospheres for their different compositions with a size radius of 10 nm to 50 nm immersed in water (n = 1.33) using the Mie theory approach are investigated theoretically. In order to determine the heat generation and the temperature distribution by plasmonic nanoparticles in the host medium (water in this study) we have solved the heat transfer equation analytically for steady-state conditions. The great utility of these bimetallic alloy nanoparticles for thermoplasmonic investigation is accompanied with a large extent of SPR tunability which is rarely found in their pure monometallic counterpart. The SPR of Aux-Cu1-x (214 nm to 548 nm), Aux-Al1-x (213 nm to 493 nm), Agx-Cu1-x (214 nm to 539 nm), and Agx-Al1-x (214 nm to 381 nm) bimetallic alloys with compositions of x = 0.25,0.50 and 0.75 have been observed for different size of the nanospheres. Thus, we anticipate that the results of this work will evoke the curiosity of researchers towards the use of bimetallic alloys in thermoplasmonic applications.

Pulsed laser-induced dewetting to fabricate Au-Pd nanoparticles supported on ZnO films and its application for the photocatalytic degradation of indigo carmine

Gold-palladium (Au-Pd) bimetallic alloy nanoparticles (NPs) were obtained by the interaction of a laser pulse with a stack of Au and Pd thin films, these films were previously and sequentially deposited on a zinc oxide (ZnO) thin films grown on a glass substrate. This method can produce, with a single laser pulse, spherical NPs of different compositions which remain attached to the surface of the ZnO film. X-ray diffraction analysis showed that the NPs are composed of a solid solution of the metals whose relative content was modified by varying the deposition time of the starting metal films. The higher amount of Pd in the NPs, the smaller particle size being the minimum around 50 nm. To demonstrate the usefulness of this method to produce Au-Pd NPs directly on surfaces, the decorated ZnO layers were tested as photocatalysts material for the decomposition of indigo carmine dye. The bimetallic NPs supported on ZnO showed to have a better photocatalytic performance to decompose the dye than their mono-metallic counterpart and bare ZnO thin film. The bimetallic NPs richer in Pd achieved a degradation of 99% of the dye while bare ZnO film reached just 32%.

Synthesis of Ni-Co alloy nanocrystalline powder by a novel chemical method and their characterization

The bimetallic or trimetallic alloy nanoparticles (NPs) are sought after in different applications due to their enhanced activity caused by the synergistic characteristics and increased surface area inherent to nano particles. The Ni-Co nanoparticles (NPs) have wide applications in biomedical field, magnetic storage media, ferrofluids, hydrogen storage, generation of hydrogen and catalytic oxidation reactions due to their good chemical stability and high magnetic anisotropy. Ultrafine particles of Ni-Co alloy were synthesized by a novel chemical method in aqueous medium using aluminum as a reducing agent. The uniqueness of this approach is that there is no need of any extra inert atmosphere to conduct the NPs synthesis. The Ni-Co alloy particles were obtained by co-reducing the nickel and cobalt metal precursors in the desired molar ratios with fixed quantity of aluminum powder. The Ni-Co NPs synthesized were having grain size less than 20 nm. The effect of cobalt content on the structure and magnetic properties of Ni-Co alloys were studied. It was observed that the formation of Ni-Co NPs alloy proceeded upto 70 % of Co. Compositional analysis showed that the precursor ratio was almost preserved in the Ni-Co alloy powders. X-ray diffraction indicated FCC structure for Ni-Co solid solution. The annealing of the synthesized Ni-Co NPs at 400 ˚C in furnace for an hour (in nitrogen atmosphere) indicated forming of well defined FCC crystalline peaks. Saturation magnetization increased as a function of Co content in Ni-Co alloy and the alloy with high Co content saturates only at a high field.

A potential recyclable catalyst: In situ growth of bimetallic Cu-Ag nanoalloy on the magnetic SiO2/Fe3O4-SiO2-NH2 nanocomposite support using a green approach

In this study, bimetallic Cu-Ag alloy nanoparticles (NPs) are anchored on the surface of magnetic functional SiO2/Fe3O4-SiO2-NH2 nanocomposite support using glucose as a green reducing agent. SiO2/Fe3O4-SiO2-NH2 nanocomposite support is prepared in one-pot via simultaneous co-precipitation of iron salts and alkaline hydrolysis-condensation reaction of tetraethyl orthosilicate (TEOS) in presence of SiO2 sphere. Hexamethylene diamine (HMDA) and cetyltrimethylammonium bromide (CTAB) are used as functional agent and structure directing agent, respectively. Finally, Cu-Ag NPs are formed on the functional nanocomposite support via in-situ green reduction protocol to obtain SiO2/Fe3O4-SiO2-NH2/Cu-Ag nanocatalyst. A comparative study of catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) showed that calcined SiO2/Fe3O4-SiO2-NH2/Cu-Ag nanocatalyst possessed higher reduction kinetics compared to corresponding non-calcined nanocatalyst. Similar enhancement in catalytic property for unsupported bimetallic Cu-Ag NPs is noticed after calcination. The incorporation of magnetic Fe3O4 in the SiO2/SiO2-NH2 support material also considerably enhanced the catalytic property of the nanocatalyst. The reduction reaction favorably followed pseudo-first-order kinetic rate model and the rate constants of non-calcined and calcined SiO2/Fe3O4-SiO2-NH2/Cu-Ag nanocatalysts are 0.0517 and 0.0998 min−1, respectively. The magnetically separable non-calcined SiO2/Fe3O4-SiO2-NH2/Cu-Ag nanocatalyst is recyclable up to five cycles with fairly acceptable conversion.

Rational Design of Highly Efficient PdIn–In2O3 Interfaces by a Capture-Alloying Strategy for Benzyl Alcohol Partial Oxidation

Well-dispersed PdIn bimetallic alloy nanoparticles (1-4 nm) were immobilized on mesostructured silica by an in situ capture-alloying strategy, and PdIn-In2O3 interfaces were rationally constructed by changing the In2O3 loading and reduction temperature. The catalytic performance for benzyl alcohol partial oxidation was evaluated, and a catalytic synergy was observed. The Pd-rich PdIn-In2O3 interface is prone to be formed on the catalyst with a low In2O3 loading after being reduced at 300 °C. It was demonstrated that the Pd-rich PdIn-In2O3 interface was more active for benzyl alcohol partial oxidation than In-rich Pd2In3 species, which was likely to be formed at a high reduction temperature (400 °C). The high catalytic activity on the Pd-rich PdIn-In2O3 interface was attributed to the exposure of more Pd-enriched active sites, and an optimized PdIn-In2O3/Pd assemble ratio enhanced the oxygen transfer during partial oxidation. The density functional theory (DFT) calculation confirmed that the Pd-rich Pd3In1(111)-In2O3 interface facilitated the activation of oxygen molecules, resulting in high catalytic activity.

Metal-organic-framework-derived bimetallic carbon-based catalysts as efficient oxygen reduction reaction electrocatalysts

The sluggish kinetics of oxygen reduction reaction (ORR) as well as costly production of current Pt/C catalysts limit the practical application of Zn-air battery (ZAB). It is challenging to synthesize an ideal ORR catalyst with intriguing features, including a conductive network, a directed pathway for charge transfer, and abundant active sites such as bimetallic alloy nanoparticles. In this work, FeCo alloys are successfully combined due to the uniform distribution of encapsulated Fe and surface-bound Co by means of electrospinning and pyrolysis. As a result, the prepared FeCo/N-CNFs have an exceptional ORR performance (E1/2 = 0.88 V, j = 5.20 mA cm−2) that considerably outperforms Pt/C (E1/2 = 0.85 V, j = 4.75 mA cm−2). In addition, ZAB based on FeCo/N-CNFs display a superior peak power density (356.23 mW cm−2) than Pt/C-ZAB (299.29 mW cm−2). The high degree of graphitization from FeCo alloy nanoparticles, the directed charge transfer channel from a one-dimensional nanofiber structure, and the interaction between M-NX and pyridine N/graphite N species all contribute to the exceptional electrocatalytic performance.

Fabrication and enhanced visible photocatalytic activity of AuPt@g-C3N4 foam

This work exhibits a remarkable enhancement in visible photocatalytic activity through the fabrication of a 0D/3D composite photocatalyst of AuPt@g-C3N4 foam. Au and Pt elements with a mole ratio of 1:1 are in the bimetallic alloy nanoparticle form, which is uniformly dispersed on the surface of g-C3N4 foam. When the average AuPt alloy nanoparticle size is 21 nm, AuPt@g-C3N4 foam shows the highest photocatalytic activity, which is about 1 time higher than that of bare g-C3N4 foam. Based on the experimental results, the enhanced photocatalytic activity of AuPt@g-C3N4 foam is mainly ascribed to the enhancement of visible-light adsorption and the acceleration of charge separation.

Dynamic Tracking of NiFe Smart Catalysts using In Situ X-Ray Absorption Spectroscopy for the Dry Methane Reforming Reaction

The exsolution of nanoparticles from perovskite precursors has been explored as a route to synthesize catalysts with sinter or coke resistance. The characteristics of these exsolved nanoparticles are highly dynamic depending on the redox nature of the environment to which they are subjected. To develop their properties for thermo- and electrocatalytic applications, it is necessary to track the states and behavior of exsolved catalysts with in situ and ex situ characterization. In this study, we conduct in situ X-ray absorption spectroscopy (XAS) along with ex situ scanning transmission electron microscopy high-angle annular dark-field (STEM-HAADF) and energy-dispersive X-ray spectroscopy analysis of the parent perovskite oxide precursor, LaFe0.8Ni0.2O3, as its structure forms bimetallic NiFe nanoparticles and evolves in oxidative, reductive, and dry methane reforming environments. We develop a theory that NiFe exsolution is a function of the reduction potential where LaFe0.8Ni0.2O3 transforms to NiFe alloy supported on LaOx-LaFeOx. The Ni starts to exsolve at 268 °C, while most Fe exsolves at 700 °C. During dry methane reforming conditions, most of the Fe is oxidized by CO2 during the reaction and re-enters the perovskite as LaFeO3, while Ni remains on the surface as nanoparticles in the metallic state. During the oxidative regeneration phase, most of the Fe re-enters the bulk perovskite phase, while Ni is partially regenerated with a small percentage oxidized to large NiO nanoparticles. This study sheds light on the exsolution and regeneration of bimetallic alloy nanoparticles and the influence of the reaction conditions on their catalyst performance.

Membrane Nanofiber-Supported Cobalt–Nickel Nanoparticles as an Effective and Durable Catalyst for H2 Evolution via Sodium Borohydride Hydrolysis

The successful support of bimetallic NiCo alloy nanoparticles (NPs) on poly(vinylidene fluoride-co-hexafluoropropylene) nanofibers (PVDF-HFP NFs) was achieved through electrospinning (ES) and in situ reduction. The synthesis and physicochemical characterization of Ni-Co@PVDF-HFP NFs with a range of bimetallic compositions (Ni1-xCox, x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, and 1) supported on PVDF-HFP NFs was undertaken. In comparison to their counterparts (Ni-PVDF-HFB and Co-PVDF-HFB), the bimetallic hybrid NF membranes demonstrated a significantly increased volume of H2 generation from sodium borohydride (SBH). The high performance of bimetallic catalysts can be attributed mostly to the synergistic impact of Ni and Co. Among all fabricated catalysts, Ni0.3Co0.7@PVDF-HFP produced the highest H2 production in a short time. The maximum generated H2volume was 118 mL in 11.5, 9, 6, and 4.5 min at 298, 308, 318, and 328 K, respectively. Kinetic analyses showed that the hydrolysis process proceeded as a quasi-first-order reaction with respect to the amount of catalyst and as a zero-order reaction with respect to the concentration of SBH. Thermodynamics studies were also undertaken and the parameters were calculated as Ea, ΔS, and ΔH = 30.17 kJ/mol, 0.065 kJ/mol, and 27.57 kJ/mol K, respectively. The introduced NFs can be easily separated and reused, which facilitates their industrialization and commercialization applications in hydrogen storage systems.

Electroless-deposition of AuPd alloy on Prussian blue derived Hematite/AuPd catalyst: Synergistic effect and potent reusable catalyst for treating environment pollutants

Electroless-deposition of bi-metallic AuPd alloy nanoparticles (5–10 nm) on Prussian blue (PB) cubes with uniform composition and size are prepared using a galvanic displacement reaction. In this study, such galvanic displacement reaction routes deed the different redox potentials of three elements (Fe, Au, and Pd) to buoy up their deposition between each other. In comparison with the previous study for the PB/Au system, verdicts in this study enlighten the significant features, possessions, and etiquettes required to form exothermic bi-metallic AuPd alloy nanoparticles onto the PB surface. The Hematite/AuPd catalyst is derived by annealing PB/AuCN–PdCN in the presence of air. During heat treatment, AuPd alloy nanoparticles anchored over the PB surface were become embedded into the Hematite crystallites and led to a core–shell structure. Such core–shell; AuPd-Hematite particles in association with “AuPd composition dependent synergism” reflects an efficient catalytic activity toward the reduction of the hazardous organic pollutant; p-nitrophenol.

Growth of carbon nanotubes over carbon nanofibers catalyzed by bimetallic alloy nanoparticles as a bifunctional electrode for Zn-air batteries.

Design of economical, large-scale, stable, and highly active bifunctional electrocatalysts for Zn-air batteries with enhanced oxygen reduction and oxygen evolution performance is needed. Herein, a series of electrocatalysts were facilely fabricated where in situ formed bimetallic nanoparticles aided in the growth of carbon nanotubes over carbon nanofibers (MM'-CNT@CNF) during thermal treatment. Different combinations of Fe, Ni, Co and Mn metals and melamine as precursor for CNT growth were investigated. The synergistic interaction between bimetallic nanoparticles and N-doped carbon results in greatly improved bifunctional catalytic activity for both oxygen reduction and evolution reactions (ORR, OER) using FeNi-CNT@CNF as catalyst. The half-wave potential (0.80 V vs. RHE) for FeNi-CNT@CNF for ORR was close to that of Pt/C (0.79 V vs. RHE), meanwhile its stability was superior to Pt/C. Likewise, during OER, the FeNi-CNT@CNF reached a current density of 10 mA cm-2 at a rather low overpotential of 310 mV vs. RHE compared to benchmark RuO2 (410 mV). The rechargeable Zn-air prototype battery using FeNi-CNT@CNF as an air electrode outperformed the mixture of Pt/C and RuO2 with discharge/charge overpotential of 0.61 V, power density of 118 mW cm-2 at 10 mA cm-2 and an improved cycling stability over 108 hours.