Bimetallic Alloy Nanoparticles Research Articles

Focused Review on the Use of Bimetallic Alloy Nanoparticle Electrocatalysts in Water Splitting Reactions

Focused Review on the Use of Bimetallic Alloy Nanoparticle Electrocatalysts in Water Splitting Reactions

Selective CO2 Reduction Electrocatalysis Using AgCu Nanoalloys Prepared by a "Host-Guest" Method.

Multimetallic nanoalloy catalysts have attracted considerable interest for enhancing the efficiency and selectivity of many electrochemically driven chemical processes. However, the preparation of homogeneous bimetallic alloy nanoparticles remains a challenge. Here, we present a room-temperature and scalable, host-guest approach for synthesis of dilute Cu in Ag alloy nanoparticles. In this approach, an ionic silver bromide precursor harboring exogenous Cu cations is reduced to yield ∼20 nm diameter AgCu alloy nanoparticles wherein the % Cu loading can be tuned precisely. AgCu nanoparticles with a 5% nominal loading of Cu exhibit peak activity (-0.23 mA/cm2 normalized partial current density) and selectivity (83.2% faradaic efficiency) for CO product formation from electrocatalytic reduction of CO2 at mild overpotentials. These AgCu nanoalloys exhibit a higher mass activity compared to Ag- and Cu-containing nanomaterials used for similar electrocatalytic transformations. Our host-guest synthesis platform holds promise for production of other nanoalloys with relevance in electrocatalysis and optics.

Effects of heating rate and sintering temperature on the tensile properties of sintered γ-Ti/Al nanoparticle chains

Abstract This paper presents the results of molecular dynamics simulations that were performed to numerically study the laser sintering process and mechanical behavior of γ-Ti/Al bimetallic alloy nanoparticles (NPs). The study systematically investigates the effects of heating rate and sintering temperature on the resultant uniaxial tensile performances of the sintered NPs. A chain model was formed by connecting three pre-equilibrated Ti/Al NPs via necks during solid-state sintering. The solid-state sintered chain samples were heated to 1798 K using four different heating rates (0.04, 0.2, 0.5, and 1.0 K/ps). After high-temperature relaxation of selected sintering temperature cases (e.g., 398 K, 598 K, etc. with a 200 K interval) for 10 ns, the heat sintered chain samples underwent a solidification process with a cooling rate of 0.08 K/ps and maintained at 298 K for an additional 1 ns. The resulting sintered chain products were then subjected to uniaxial tension at a strain rate of 0.0001/ps. The thermodynamic properties and crystallographic deformation were investigated during the sintering and subsequent tension processes. Analysis of the yield strengths obtained from the tension tests revealed a statistically significant correlation between the tensile strength of the sintered NPs and the pre-established sintering temperatures at each temperature. This observation indicates that higher sintering temperatures strengthen the neck connections within the NP-chains, leading to greater tensile strength. The higher sintering temperatures can reinforce the neck during high-temperature relaxation. It is worth noting that the effect of heating rates on mechanical properties was less pronounced when the sintering temperature was constant.

Reversibility in Structural Dynamics on Pt−Ni Bimetallic Nanocrystals under Redox Conditions

AbstractThe reversibility of structural change in a bimetallic catalyst during the chemical reaction is an essential factor to determine the catalytic stability. Herein, we investigate the surface modulation of three Pt−Ni bimetallic alloy nanoparticle compositions (Pt3Ni1, Pt1Ni1, and Pt1Ni3) under alternating redox cycles. We validate trends in the structural change of the three compositions of Pt−Ni nanoparticles via spectroscopic/microscopic investigations at bulk and atomic levels. Pt‐rich Pt−Ni nanoparticles exhibited higher reversibility in structural change during the repeated redox cycles. On the contrary, Ni‐rich Pt−Ni nanoparticles showed irreversible structural changes, leading to the segregation and separation of Ni species from the alloy, which could deactivate the catalysts. This work demonstrates the reversibility of structural dynamics in alloy catalysts depending on their composition, providing fundamental insights for developing ideal bimetallic catalysts.

Interband and Intraband Hot Carrier-Driven Photocatalysis on Plasmonic Bimetallic Nanoparticles: A Case Study of Au-Cu Alloy Nanoparticles.

Photoexcited nonthermal electrons and holes in metallic nanoparticles, known as hot carriers, can be judiciously harnessed to drive interesting photocatalytic molecule-transforming processes on nanoparticle surfaces. Interband hot carriers are generated upon direct photoexcitation of electronic transitions between different electronic bands, whereas intraband hot carriers are derived from nonradiative decay of plasmonic electron oscillations. Due to their fundamentally distinct photogeneration mechanisms, these two types of hot carriers differ strikingly from each other in terms of energy distribution profiles, lifetimes, diffusion lengths, and relaxation dynamics, thereby exhibiting remarkably different photocatalytic behaviors. The spectral overlap between plasmon resonances and interband transitions has been identified as a key factor that modulates the interband damping of plasmon resonances, which regulates the relative populations, energy distributions, and photocatalytic efficacies of intraband and interband hot carriers in light-illuminated metallic nanoparticles. As exemplified by the Au-Cu alloy nanoparticles investigated in this work, both the resonant frequencies of plasmons and the energy threshold for the d-to-sp interband transitions can be systematically tuned in bimetallic alloy nanoparticles by varying the compositional stoichiometries and particle sizes. Choosing photocatalytic degradation of Rhodamine B as a model reaction, we elaborate on how the variation of the particle sizes and compositional stoichiometries profoundly influences the photocatalytic efficacies of interband and intraband hot carriers in Au-Cu alloy nanoparticles under different photoexcitation conditions.

The substantial role of TiO2 in bimetallic alloy nanoparticle arrangement: electrocatalytic determination of glucose at Ni-Co@TiO2@GCE

The substantial role of TiO2 in bimetallic alloy nanoparticle arrangement: electrocatalytic determination of glucose at Ni-Co@TiO2@GCE

Nanoengineering of mono (Au, Ag) and bimetallic (Ag-Au) alloy nanoparticles for dye degradation and toxicity assessment

This research entails the synthesis and catalytic exploration of bimetallic nanoparticles combining silver (Ag) and gold (Au). The Au concentration was systematically varied (20%, 40%, 60%, and 80%), alongside the utilization of CTAB surfactant for nanoparticle stabilization. UV visible spectroscopic analysis confirmed the formation and stability of synthesized Au, Ag and bimetallic (Ag-Au) nanoparticles. FESEM further confirmed the formation of uniform sized Au and Ag nanoparticles. Integration of Au into Ag resulted in bimetallic (Ag-Au) alloy nanoparticles with smaller dimensions as compared to individual Au and Ag nanoparticles. EDX spectra and mapping verified the composition of each synthesized bimetallic nanoparticle variant. The catalytic potential of the synthesized nanoparticles was methodically explored using UV–visible spectroscopy. All the synthesized nanoparticles showcased excellent catalytic efficacy. The synergistic effect of the alloyed bimetallic nanoparticles was found promising. Assessment of dye toxicity pre- and post-degradation was conducted using the ECOSAR program, indicating a reduction in dye toxicity following degradation.

Ligand-Induced Atomically Segregation-Tunable Alloy Nanoprobes for Enhanced Magnetic Resonance Imaging.

Bimetallic iron-noble metal alloy nanoparticles have emerged as promising contrast agents for magnetic resonance imaging (MRI) due to their biocompatibility and facile control over the element distribution. However, the inherent surface energy discrepancy between iron and noble metal often leads to Fe atom segregation within the nanoparticle, resulting in limited iron-water molecule interactions and, consequently, diminished relaxometric performance. In this study, we present the development of a class of ligand-induced atomically segregation-tunable alloy nanoprobes (STAN) composed of bimetallic iron-gold nanoparticles. By manipulating the oxidation state of Fe on the particle surface through varying molar ratios of oleic acid and oleylamine ligands, we successfully achieve surface Fe enrichment. Under the application of a 9 T MRI system, the optimized STAN formulation, characterized by a surface Fe content of 60.1 at %, exhibits an impressive r1 value of 2.28 mM-1·s-1, along with a low r2/r1 ratio of 6.2. This exceptional performance allows for the clear visualization of hepatic tumors as small as 0.7 mm in diameter in vivo, highlighting the immense potential of STAN as a next-generation contrast agent for highly sensitive MR imaging.

Construction of Metal/Zeolite Hybrid Nanoframe Reactors via in-Situ-Kinetics Transformations.

Metal/zeolite hybrid nanoframes featuring highly accessible compartmental environments, abundant heterogeneous interfaces, and diverse chemical compositions are expected to possess significant potential for heterogeneous catalysis, yet their general synthetic methodology has not yet been established. In this study, we developed a two-step in-situ-kinetics transformation approach to prepare metal/ZSM-5 hybrid nanoframes with exceptionally open nanostructures, tunable metal compositions, and abundant accessible active sites. Initially, the process involved the formation of single-crystalline ZSM-5 nanoframes through an anisotropic etching and recrystallization kinetic transformation process. Subsequently, through an in situ reaction of the Ni2+ ions and the silica species etched from ZSM-5 nanoframes, layered nickel silicate emerged on both the inner and outer surfaces of the zeolite nanoframes. Upon reduction under a hydrogen atmosphere, well-dispersed Ni nanoparticles were produced and immobilized onto the ZSM-5 nanoframes. Strikingly, this strategy can be extended to immobilize a variety of ultrasmall monometallic and bimetallic alloy nanoparticles on zeolite nanoframes. Benefiting from the structural and compositional advantages, the resultant hybrid nanoframes with a high loading of discrete Ni nanoparticles exhibited enhanced performance in the hydrodeoxygenation of stearic acid into liquid fuels. Overall, the methodology shares fresh insights into the rational construction of intricate frame-like metal/zeolite hybrid nanoreactors for many potential catalytic applications.

Development of pectin-based gel electrolyte for wireless electrochemical determination of cadmium and lead using smartphone

A portable device offering effortlessness, mobility, and affordability for real-time and on-site monitoring of heavy metals is currently in great demand to maintain environmental sustainability. Herein, a platform utilizing a biopolymeric gel-based electrolyte for the on-field simultaneous determination of Cd(II) and Pb(II) is described. Pectin, a natural polymer, was exploited as a chemical delivery medium on account of its biodegradability, environmental friendliness, and rapid dissolving characteristics. The gel electrolyte was prepared by having pectin dissolved in KCl mixed with Sb(III)–Bi(III) bimetallic alloy solution, and casted onto a paper substrate. An in situ bimetallic alloy and pre-mixed bismuth nanoparticles modified screen-printed graphene electrode (Sb–Bi/BiNP/SPGE) were employed to enhance the electrochemical signals of Cd(II) and Pb(II) for the differential pulse anodic stripping voltammetry (DPASV). It was demonstrated that the platform was capable of generating sharp and well-defined current signals, achieving the low detection limits of 50.98 ng mL−1 for Cd(II) and 40.80 ng mL−1 for Pb(II). The reproducibility, as indicated by the relative standard deviation, was found to be less than 10.4 % (n = 10) for the developed gel-based device when coupled with a wireless near field communication (NFC) potentiostat. Lastly, the obtained sensor was applied for quantification of Cd and Pb in potentially contaminated groundwater samples. The recoveries obtained were satisfactorily within the acceptable range. The newly designed platform exhibited several advantages, including small sample volume (μL), low-cost, no sample preparation requirements, and being environmentally friendly. The convenience of a portable device utilizing the proposed biopolymeric gel-based electrolyte for on-field analysis makes it highly appealing for various applications.

Refining laser-induced dewetting for bimetallic Au–Pd nanoparticle synthesis on ZnO thin films: Optimizing fluence for substrate integrity

We report the fabrication of metal alloy Au–Pd nanoparticles on semiconductor thin film substrates (ZnO) by laser-induced dewetting. Employing a UV excimer laser, a single pulse was directed onto a three-layer film stack on a glass substrate: glass/ZnO/Au/Pd and glass/ZnO/Pd/Au. We simulated the temperature attained by the thin films enabling the prediction of energy thresholds required for melting the metal films but avoiding modifying the ZnO film. A specific range is reported of the pulse energy conducive to nanoparticle formation and the energy threshold required to modify the ZnO film beneath them. Depending on the pulse energy applied, the mean diameter of the nanoparticles varied from approximately 150 to around 70 nm. Notably, higher fluences resulted in smaller particles but also induced surface cracks in the ZnO film. Additionally, we observed a reduction in nanoparticle size with increased Pd content. Our results show that laser-induced dewetting can produce bimetallic alloy nanoparticles and, at the same time, ensure the preservation of the optical properties of the ZnO film. This approach opens avenues for tailoring material characteristics and expanding the range of applications of metal nanoparticles on semiconductor-based systems.

Ruthenium-Cobalt Solid-Solution Alloy Nanoparticles for Enhanced Photopromoted Thermocatalytic CO2 Hydrogenation to Methane.

Bimetallic alloy nanoparticles have garnered substantial attention for diverse catalytic applications owing to their abundant active sites and tunable electronic structures, whereas the synthesis of ultrafine alloy nanoparticles with atomic-level homogeneity for bulk-state immiscible couples remains a formidable challenge. Herein, we present the synthesis of RuxCo1-x solid-solution alloy nanoparticles (ca. 2 nm) across the entire composition range, for highly efficient, durable, and selective CO2 hydrogenation to CH4 under mild conditions. Notably, Ru0.88Co0.12/TiO2 and Ru0.74Co0.26/TiO2 catalysts, with 12 and 26 atom % of Ru being substituted by Co, exhibit enhanced catalytic activity compared with the monometallic Ru/TiO2 counterparts both in dark and under light irradiation. The comprehensive experimental investigations and density functional theory calculations unveil that the electronic state of Ru is subtly modulated owing to the intimate interaction between Ru and Co in the alloy nanoparticles, and this effect results in the decline in the CO2 conversion energy barrier, thus ultimately culminating in an elevated catalytic performance relative to monometallic Ru and Co catalysts. In the photopromoted thermocatalytic process, the photoinduced charge carriers and localized photothermal effect play a pivotal role in facilitating the chemical reaction process, which accounts for the further boosted CO2 methanation performance.

Precision Synthesis of Sub-3 nm Bimetallic Alloy Nanoparticles for Efficient and Selective Catalytic Hydrogenolysis of 5-Hydroxymethylfurfural to 2,5-Dimethylfuran

Precision Synthesis of Sub-3 nm Bimetallic Alloy Nanoparticles for Efficient and Selective Catalytic Hydrogenolysis of 5-Hydroxymethylfurfural to 2,5-Dimethylfuran

Bimetallic alloy nanoparticles embedded in N-doped carbon-based as an anode for potassium-ion storage material

Metal-organic frameworks (MOFs) have great potential as anode materials for potassium-ion batteries (PIBs) due to their hierarchical porous structures, large number of reaction sites, and adjustable chemistry. However, the larger size of potassium ions adversely impacts the electrochemical performance and specific capacity. Therefore, it is imperative to develop novel electrode materials featuring distinctive structures for PIBs. This study achieved bimetal introduction by adding Ammonium ferric citrate during ZIF-67 growth. The resulting metal–organic skeleton of the bimetallic alloy nanoparticle (FeCo@PAZ-C) exhibits a core–shell structure and adorned with numerous microspheres on its surface, thereby offering an abundance of active sites for K+ storage. This architecture effectively reduces the diffusion path length for potassium ions and enhances electron transport pathways, ultimately contributing to improved performance. At 100 mA g−1 and after 500 cycles, the FeCo@PAZ-C electrode material demonstrated a stable specific capacity of 328 mAh/g with 95 % capacity retention. This self-sacrificing template method for MOFs offers a new approach to developing high-capacity and cycling-stable potassium-ion battery materials, broadening their potential applications.

Enhanced electrocatalytic performance of PtNi bimetallic alloys on carbon nanotube for ethanol oxidation reaction

In this paper, Ni-Pt bimetallic alloy nanoparticles were loaded on carbon nanotubes to prepare Ni-Pt nanoparticles/carbon nanotubes composites (Ni-Pt NPs/CNTs) as excellent catalytic materials for ethanol electro-oxidation reaction (EOR). X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and special aberration corrected transmission electron microscope (STEM) were used to characterize its morphology and structure. The activity and stability of the composite were measured by cyclic voltammetry (CV) and chronoamperometry (CA). The catalytic performance was explored by adjusting the ratio of Ni to Pt. Performance test results showed that the Ni-Pt alloy formed 10–15 nm spherical particles and dispersed uniformly on the surface of carbon nanotubes. The Ni1Pt1 NPs/CNTs composite showed excellent performance for EOR. Its mass activity of ethanol electro-oxidation was 620 mA·mg−1Pt, which was 5.08, 18.2 times higher than that of commercial Pt/C and Pt black catalyst, respectively.

Selective Reduction of Multivariate Metal-Organic Frameworks for Advanced Electrocatalytic Cathodes in High Areal Capacity and Long-Life Lithium-Sulfur Batteries.

Lithium-sulfur batteries hold great promise as next-generation high-energy-density batteries. However, their performance has been limited by the low cycling stability and sulfur utilization. Herein, we demonstrate that a selective reduction of the multivariate metal-organic framework, MTV-MOF-74 (Co, Ni, Fe), transforms the framework into a porous carbon decorated with bimetallic CoNi alloy and Fe3O4 nanoparticles capable of entrapping soluble lithium polysulfides while synergistically facilitating their rapid conversion into Li2S. Electrochemical studies on coin cells containing 89 wt % sulfur loading revealed a reversible capacity of 1439.8 mA h g-1 at 0.05 C and prolonged cycling stability for 1000 cycles at 1 C/1060.2 mA h g-1 with a decay rate of 0.018% per cycle. At a high areal sulfur loading of 6.9 mg cm-2 and lean electrolyte/sulfur ratio (4.5 μL:1.0 mg), the battery based on the 89S@CoNiFe3O4/PC cathode provides a high areal capacity of 6.7 mA h cm-2. The battery exhibits an outstanding power density of 849 W kg-1 at 5 C and delivers a specific energy of 216 W h kg-1 at 2 C, corresponding to a specific power of 433 W kg-1. Density functional theory shows that the observed results are due to the strong interaction between the CoNi alloy and Fe3O4, facilitated by charge transfer between the polysulfides and the substrate.

Bimetallic PdPt alloy nanoparticle-decorated track-etched polyethylene terephthalate membranes for efficient H2 separation

Bimetallic PdPt alloy nanoparticles of particle size 8 nm, which show high affinity towards H2 gas, were synthesized using a wet chemical synthesis process.

Remarkably enhanced hydrogen evolution of g-C3N4 nanosheet under simulated sunlight via AgPt alloy co-catalyst with low amount of Pt

The development of low-cost co-catalysts matched with proper photocatalysts to enhance the photocatalytic hydrogen evolution performance is highly demanded. Herein, the AgPt bimetallic alloy nanoparticles with small amounts of Pt were decorated on g-C3N4 nanosheets (AP-CN) via the NaBH4 reduction method, which were further used as catalysts towards photocatalytic hydrogen evolution from water under AM1.5 irradiation. Compared to mono-metallic co-catalysts, bimetallic AgPt alloy nanoparticles exhibited excellent co-catalytic performance. The optimum AP-CN photocatalyst with 0.5 wt% Pt exhibited photocatalytic hydrogen evolution rate of 3507.89 μmol g−1·h−1, which even surpassed that of the commonly-used photocatalyst 1.0 wt% Pt in-situ photo-deposited on g-C3N4. Meanwhile, the AP-CN showed excellent photocatalytic activity and durability after four experimental cycles. The enhanced activity and stability could be attributed to the synergistic effect between plasmonic metal Ag and Pt, which promoted the transfer and separation of photoinduced charge carriers. Besides, the theoretical results based on DFT calculation also verified that AgPt alloys have better performance of desorbing hydrogen and adsorbing H atoms. This work provides a feasible idea for the development of inexpensive and efficient bimetallic co-catalysts for photocatalytic hydrogen production through water splitting.

Ni‐Pt Bimetallic Alloy Nanoparticles Dispersed Uniformly on Carbon Nanotubes for Efficient Electrooxidation Methanol

AbstractIn this paper, Ni−Pt bimetallic alloy nanoparticles were loaded on carbon nanotubes to construct Ni−Pt nanoparticles/carbon nanotubes (Ni−Pt NPs/CNTs) composites as excellent catalytic materials for methanol electrooxidation reaction (MOR). X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), and special aberration corrected transmission electron microscope (STEM) were employed to investigate the morphology of the material. It was confirmed that the Ni−Pt alloy nanoparticles dispersed uniformly on the surface of carbon nanotubes. The activity and stability of Ni−Pt NPs/CNTs composites were measured by chronoamperometry (CA), linear sweep voltammetry (LSV) and cyclic voltammetry (CV). The catalytic performance was explored by adjusting the ratio of Ni to Pt. The Ni1Pt2 NPs/CNTs composite showed excellent performance for MOR. Its mass activity for MOR was 1255 mA ⋅ mg−1Pt, which was 2.76, 2.56 times as that of commercial Pt/C, Pt black catalyst, respectively. Moreover, the resistance to CO toxicity of Ni1Pt2 NPs/CNTs composite was better than commercial Pt/C and Pt black catalyst.

FeCo Bimetallic Alloy Nanoparticles Embedded in Nitrogen-Doped Porous Carbon for Effective Oxygen Reduction in Zinc–Air Batteries

FeCo Bimetallic Alloy Nanoparticles Embedded in Nitrogen-Doped Porous Carbon for Effective Oxygen Reduction in Zinc–Air Batteries