Ultrathin Alloy Research Articles

Electronic structure modulation of ultrathin PtRuMoCoNi high-entropy alloy nanowires for boosting peroxidase-like activity and sensitive colorimetric determinationof isoniazid and hydrazine.

Self-supported ultrathin PtRuMoCoNi high-entropy alloy nanowires (HEANWs) were synthesized by a one-pot co-reduction method, whose peroxidase (POD)-like activity and catalytic mechanism were elaborated in detail. As expected, the PtRuMoCoNi HEANWs showed excellent POD-like activity. It can quickly catalyze the oxidization of colorless 3,3',5,5'-tetramethylbenzidine (TMB) to blue OXTMB through decomposition of H2O2 to superoxide radicals. Notably, isoniazid and hydrazine effectively scavenge the as-produced superoxide radicals and reduce the blue OXTMB, showing high reduction ability and antioxidant property. Thus, the PtRuMoCoNi HEANW-derived colorimetric method was developed for determination of isoniazid and hydrazine, which exhibited the linear ranges of 1.5 to 50μM and 25 to 200μM coupled with the lower detection limits of 2.3 and 12.6μM for isoniazid and hydrazine, respectively. The excellent analytical performance mainly results from the synergistic catalytic effect of the multiple metals and distinctive ultra-thin nanowires. This work provides a simple and rapid colorimetric method for the determination of isoniazid and hydrazine in actual samples.

Adjacent-Ligand Tuning of Atomically Precise Cu-Pd Sites Enables Efficient Methanol Electrooxidation with a CO-Free Pathway.

Whether the catalyst can realize the non-CO pathway is the key to greatly improve the catalytic activity and stability of methanol oxidation reaction (MOR). It is feasible to optimize the reaction path selectivity by modifying organic ligands and constructing single-atom systems. At the same time, heterogeneous metal nanosheets with atomic thickness have been shown to significantly enhance the catalytic activity of materials due to their ultra-high exposure of active sites and synergistic effects. Herein, we synthesize an ultra-thin heterogeneous alloy metallene with organic ligand-modified surface Cu single atom by one-pot wet chemical method, and further construct an efficient Cu-Pd active sites. The prepared octanoic acid ligand modified PdCu single-atom alloys metallene (SAA OA-Cu-Pdene) shows excellent catalytic activity and stability, with mass activity up to 5.64 A mgPd -1 and electrochemical active surface area (ECSA) up to 160.39 m2 gPd -1. Structural characterization and in situ experiment jointly indicate that ligand modulation brings about charge transfer, and the accompanying rapid migration of OH- greatly improves the selectivity of non-CO pathways while improving the catalytic activity. The results highlight the importance of adjacent-ligand regulation and provide a new strategy for the design of MOR catalysts with high selectivity of non-CO pathway.

Zn-Sn Alloy Seed Layer-Coated Cu Current Collector for Anode-Free Aqueous Zn Ion Batteries

Zn ion batteries (ZIB) stand at the forefront of alternative advanced energy storage technologies due to the intrinsic properties of Zn, including its low reduction potential (-0.76 V vs. SHE), and high theoretical specific capacity (820 mAh g-1) acquired by its multi-electron redox processes. Nonetheless, the utilization of current thick Zn foil anode remains a big challenge to commercialization, caused by the dendrite growth, severe surface side reaction, and high N/P ratio, which leads to the limitation of cell energy density. Herein, we report anode-free technology based on ultra-thin Zn-Sn alloy seed layer-coated Cu foil (ASL@Cu), to break through the limit of cell energy density. Incorporating Sn and carbon in the seed layer results in a strong affinity towards Zn, inhibiting the irreversible surface reactions, and eventually offering efficient electron transport routes. The resulting ASL showed rapid kinetics for Zn2+ deposition (lower nucleation overpotential) and exhibited an extended cycle life at a current density of 4 mA cm-2. This work sheds light on the strategic design of anode-free to achieve outstanding performance with a constrained amount of Zn on the Cu current collector.

Proximity-Induced Superconductivity in a 2D Kondo Lattice of an f-Electron-Based Surface Alloy.

Realizing hybrids of low-dimensional Kondo lattices and superconducting substrates leads to fascinating platforms for studying the exciting physics of strongly correlated electron systems with induced superconducting pairing. Here, we report a scanning tunneling microscopy and spectroscopy study of a new type of two-dimensional (2D) La-Ce alloy grown epitaxially on a superconducting Re(0001) substrate. We observe the characteristic spectroscopic signature of a hybridization gap evidencing the coherent spin screening in the 2D Kondo lattice realized by the ultrathin La-Ce alloy film on normal conducting Re(0001). Upon lowering the temperature below the critical temperature of rhenium, a superconducting gap is induced exhibiting an energy asymmetry of the coherence peaks that arises from the interaction of residual unscreened magnetic moments with the superconducting substrate. A positive correlation between the Kondo hybridization gap and the asymmetry of the coherence peaks is found.

Ultrathin ternary PtNiRu nanowires for enhanced oxygen reduction and methanol oxidation catalysis via d-band center regulation

Direct methanol fuel cells rely on the efficiency of their anode/cathode electrocatalysts to facilitate the methanol oxidation reaction and oxygen reduction reaction, respectively. Platinum-based nanocatalysts are at the forefront due to their superior catalytic properties. However, the high-cost, scarcity, and low CO tolerance of platinum pose challenges for the scalable application of DMFCs. Herein, we report novel ultrathin ternary PtNiRu alloy nanowires to improve Pt utilization and CO tolerance. These novel electrocatalysts incorporate the oxophilic metal Ru into ultrathin PtNi nanowires, aiming to enhance the intrinsic activity of platinum while leveraging the long-term durability and high utilization efficiency provided by the bimetallic synergistic effect. The PtNiRu NWs significantly enhance both mass activity and specific activity for ORR, performing about 6.9 times and 3.9 times better than commercial Pt/C, respectively. After a rigorous durability test of 10,000 cycles, the PtNiRu NWs only exhibited a 25.2 % loss in mass activity. Additionally, for MOR, the MA and SA of PtNiRu NWs exceed that of Pt/C catalyst by 4.30 and 2.72 times, respectively, and exhibit exceptional resistance to CO poisoning. Theoretical insights from density functional theory calculations suggest that the introduction of Ru modulates the d-band center of the surface Pt atoms, which contributes to decreased binding strength of oxygenated species and an elevated dissolution potential, substantiating the enhanced performance metrics, and the durability enhancement stems from the stronger PtM bonds than those in PtNiRu NWs resulted from PtRu covalent interactions. These findings not only provide a new perspective on platinum-based nanocatalysts but also significantly advance the quest for more efficient and durable electrocatalysts for DMFCs, representing a substantial stride in fuel cell technology.

Ultrathin Ternary FeCoNi Alloy Nanoarrays in BaTiO3 Matrix for Room-Temperature Multiferroic and Hyperbolic Metamaterial.

Multifunctional vertically aligned nanocomposite (VAN) thin films exhibit considerable potential in diverse fields. Here, a BaTiO3-FeCoNi alloy (BTO-FCN) system featuring an ultrathin ternary FCN alloy nanopillar array embedded in the BTO matrix has been developed with tailorable nanopillar size and interpillar distance. The magnetic alloy nanopillars combined with a ferroelectric oxide matrix present intriguing multifunctionality and coupling properties. The room-temperature magnetic response proves the soft magnet nature of the BTO-FCN films with magnetic anisotropy has been demonstrated. Furthermore, the anisotropic nature of the dielectric-metal alloy VAN renders it an ideal candidate for hyperbolic metamaterial (HMM), and the epsilon-near-zero (ENZ) wavelength, where the real part of permittivity (ε') turns to negative, can be tailored from ∼700 nm to ∼1050 nm. Lastly, room-temperature multiferroicity has been demonstrated via interfacial coupling between the magnetic nanopillars and ferroelectric matrix.

Ultra-Thin RuIr Alloy as Durable Electrocatalyst for Seawater Hydrogen Evolution Reaction.

The development of efficient, high-performance catalysts for hydrogen evolution reaction (HER) remains a significant challenge, especially in seawater media. Here, RuIr alloy catalysts are prepared by the polyol reduction method. Compared with single-metal catalysts, the RuIr alloy catalysts exhibited higher activity and stability in seawater electrolysis due to their greater number of reactive sites and solubility resistance. The RuIr alloy has an overpotential of 75 mV@10mA cm-2, which is similar to that of Pt/C (73mV), and can operate stably for 100 hours in alkaline seawater. Density functional theory (DFT) calculations indicate that hydrogen atoms adsorbed at the top sites of Ru and Ir atoms are more favorable for HER and are most likely to be the reactive sites. This work provides a reference for developing highly efficient and stable catalysts for seawater electrolysis.

Phase Composition and Structure of Ultrathin Nanocrystalline Cu-Ni Film Alloys

The results of studying the morphology, crystal structure and phase composition of ultrathin Cu-Ni alloy films with thicknesses up to d = 10 nm and concentrations 0 < Cu < 100 at.% are presented.

Realizing Ultrathin LiSn Alloy Anode by Tuning the Wettability of Molten Li for High-Energy-Density Batteries.

Despite being heralded as the "holy grail" of anodes for their high theoretical specific capacity, lithium (Li) metal anodes still face practical challenges due to difficulties in fabricating ultrathin Li with controllable thickness and suppressing Li dendrites growth. Herein, we introduce a simple and cost-effective dip-coating method to fabricate ultrathin lithium-tin (LiSn) anode with adjustable thicknesses ranging from 4.5 to 45 μm. The in situ formation of Li22Sn5 alloy improves the wettability of the molten Li, enabling the casting of ultrathin Li metal layers on different substrates. More importantly, the abundant Li22Sn5 lithiophilic sites significantly lower the nucleation overpotential, inducing uniform Li deposition and accelerating the electrochemical reaction at the interface. As a result, the symmetric cell assembled with LiSn-Cu electrodes can cycle stably for more than 120 h with a charge/discharge depth of 50%, which is 1.5 times longer than the lifespan of the pure Li anode. In the full cells paired with NCM cathode, the discharge specific capacity is improved from 13.84 to 70.31 mA h g-1 with the LiSn-Cu anode at 8 C. The LiSn-Cu||NCM full cell realized a high energy density of 724.9 Wh kg-1 at the active material level with an N/P ratio of 1.4.

Synergistic signal amplification of ultrathin nanowire-like PtCoFeRuMo high-entropy nanozyme and Z-scheme WO3/ZnIn2S4 heterostructure for split-typed photoelectrochemical aptasensing of myoglobin

Enzyme-initiated sensing strategy has wide applications in photoelectrochemical (PEC) analysis for its high specificity and excellent catalytic efficiency. Herein, ultrathin PtCoFeRuMo high-entropy alloy nanowires (PtCoFeRuMo HEANWs) were prepared by a simple solvothermal method, whose peroxidase-like (POD-like) catalytic property was critically investigated by tetramethylbenzidine (TMB) oxidation in the presence of H2O2. Simultaneously, Z-scheme WO3/ZnIn2S4 heterostructures (labeled WO3/ZnIn2S4) were constructed under solvothermal treatment, whose optical properties and photoactivity were rigorously studied by a set of techniques, combined by elaborating the interfacial charge transfer mechanism. On such foundation, a split-typed PEC aptasensor was established with the WO3/ZnIn2S4 substrate, whose detection signals were further magnified through catalytic oxidation of 3-amino-9-ethylcarbazole (AEC) initiated by the PtCoFeRuMo HEANWs. The resultant PEC sensor realized excellent bioanalysis of biomarker myoglobin, showing a broader linear range from 1.0 × 10−2 to 1.0 × 105 pg mL−1 and a lower limit of detection (0.96 fg mL−1, S/N = 3). This split-typed PEC biosensing strategy shows substantial promise in bioanalysis and clinical diagnosis.

Engineering Ultrathin Alloy Shell in Au@AuPd Core‐Shell Nanoparticles for Efficient Plasmon‐Driven Photocatalysis

AbstractBimetallic core‐shell nanoparticles (NPs) possessing a synergetic coupling of plasmonic and catalytic metals have emerged as promising prototypes for efficient plasmon‐driven photocatalysis. Here, Au@AuPd core‐shell NPs composed of Au core NP and ultrathin AuPd shell are introduced to acquire improved light utilization efficiency in photocatalytic selective oxidation. With systematical control of the composition of the ultrathin alloy shell, it reveals that the Au@AuPd core‐shell NPs with 10 at% Pd (in the single‐atom alloy regime) is an effective nanostructure capable of maximizing the quantum yield of plasmon‐induced light absorption and optimizing the surface electronic structure for catalytic reactions. This controlled system provides new insights into shell engineering for enhancing photocatalytic performance via the regulation of energy funneling processes in core‐shell nanocatalysts.

Edge-controlled ultrathin PdAg/PdPtAg ternary nanosheets for efficient ethanol oxidation reaction

Ultrathin metal alloy nanosheets offer promising applications in electrocatalysis due to their superior performance. In this study, we present a rational synthesis of ternary alloy ultrathin PdAg/PtPdAg nanosheets possessing highly porous edges (PdAg/PtPdAg P-NSs). By adopting mild reduction conditions and eliminating the need for strong surface-binding stabilizers, we effectively suppressed 3D growth and stabilized the unstable edges, resulting in ultrathin nanosheets with highly porous features. Importantly, these PdAg/PtPdAg P-NSs demonstrate remarkable electrocatalytic performances for the ethanol oxidation reaction, outperforming both their ternary counterparts and commercial Pd/C catalysts. This innovative synthetic approach offers a pathway to the design of high-performance 2D electrocatalysts for a broad spectrum of applications.

Cascaded p-d Orbital Hybridization Interaction in Ultrathin High-Entropy Alloy Nanowires Boosts Complete Non-CO Pathway of Methanol Oxidation Reaction.

Designing high efficiency platinum (Pt)-based catalysts for methanol oxidation reaction (MOR) with high "non-CO" pathway selectivity is strongly desired and remains a grand challenge. Herein, PtRuNiCoFeGaPbW HEA ultrathin nanowires (HEA-8 UNWs) are synthesized, featuring unique cascaded p-d orbital hybridization interaction by inducing dual p-block metals (Ga and Pb). In comparison with Pt/C, HEA-8 UNWs exhibit 15.0- and 4.2-times promotion of specific and mass activity for MOR. More importantly, electrochemical in situ FITR spectroscopy reveals that the production/adsorption of CO (CO*) intermediate is effectively avoided on HEA-8 UNWs, leading to the complete "non-CO" pathway for MOR. Theoretical calculations demonstrate the optimized electronic structure of HEA-8 UNWs can facilitates a lower energy barrier for the "non-CO" pathway in the MOR.

Unlocking the Mechanism for Achieving Excellent Thermal Stability in Ultra-Thin AZ61 Mg Alloy Foil

Unlocking the Mechanism for Achieving Excellent Thermal Stability in Ultra-Thin AZ61 Mg Alloy Foil

Crystal Phase Engineering of Ultrathin Alloy Nanostructures for Highly Efficient Electroreduction of Nitrate to Ammonia.

Electrocatalytic nitrate reduction reaction (NO3RR) toward ammonia synthesis is recognized as a sustainable strategy to balance the global nitrogen cycle. However, it still remains a great challenge to achieve highly efficient ammonia production due to the complex proton-coupled electron transfer process in NO3RR. Here, the controlled synthesis of RuMo alloy nanoflowers (NFs) with unconventional face-centered cubic (fcc) phase and hexagonal close-packed/fcc heterophase for highly efficient NO3RR is reported. Significantly, fcc RuMo NFs demonstrate high Faradaic efficiency of 95.2% and a large yield rate of 32.7mg h-1 mgcat -1 toward ammonia production at 0 and -0.1V (vs reversible hydrogen electrode), respectively. In situ characterizations and theoretical calculations have unraveled that fcc RuMo NFs possess the highest d-band center with superior electroactivity, which originates from the strong Ru─Mo interactions and the high intrinsic activity of the unconventional fcc phase. The optimal electronic structures of fcc RuMo NFs supply strong adsorption of key intermediates with suppression of the competitive hydrogen evolution, which further determines the remarkable NO3RR performance. The successful demonstration of high-performance zinc-nitrate batteries with fcc RuMo NFs suggests their substantial application potential in electrochemical energy supply systems.

Comparative study of femtosecond laser-induced ultrafast magnetization dynamics in soft ferromagnetic ultra-thin alloy

The typical demagnetization mechanism is applicable in magneto-optic recording systems on a nanoseconds timescale. Interest in this area has expanded rapidly since understanding the physics of ultrafast magnetization processes by experiment are an acutely challenging task. As a result, in order to explain the quenching of magnetization by laser heating in ferromagnetic alloys such as permalloy, we executed a new theoretical study on permalloy, as well as Ni and Fe ultra-thin films with thickness varying from 1 nm to 5 nm. In particular, we demonstrate that the magnetization decays in a timescale of about 0.1 picosecond by the microscopic three-temperature model. Our free electron model-based theoretical model represents that electron–phonon coupling coefficient and demagnetization time in the thin-films are strongly sensitive to film thickness, pulse duration and laser fluence, respectively. In particular, we show that the rapid demagnetization (100 fs) is due to electron-magnon excitation. This feature improves data processing speed in communication systems and the recording industry.

High-performance electrocatalytic reduction of CO2 to CO by ultrathin PdCu alloy nanosheets

Electrochemical reduction of carbon dioxide (CO2RR) into fuels and chemicals is a significant step to balance the carbon cycle. For CO2 reduction to CO, the binding energy of intermediates *COOH and *CO is crucial for the electrocatalytic activity and selectivity. Herein, we prepare a series of ultrathin and tunable PdCu alloy nanosheets by a one-pot wet chemistry process and demonstrate that the bimetallic nanosheets can improve the electronic configurations and break the inherent scaling relationship of intermediate binding energy, which leads to a high performance of CO2RR. Specifically, Pd1Cu1 exhibits the best CO2RR performance among the series, with a faraday efficiency (FE) of 97% CO at − 0.80 V vs reversible hydrogen electrode (RHE) in 0.1 M KHCO3 and 96% at − 0.88 V in 1 M KOH with a current density of 521 mA cm−2. This is ascribed to moderate *COOH binding and weak binding of *CO on Pd1Cu1, as manifested in both experimental and theoretical studies. Results from this work highlight the unique potentials of bimetallic alloy nanosheets as high-performance catalysts for electrochemical reduction of CO2.

Formation mechanism of texture in ultra-thin Fe Si alloy sheet with excellent medium frequency magnetic properties fabricated by multi-stage decarburizing and cold rolling

Formation mechanism of texture in ultra-thin Fe Si alloy sheet with excellent medium frequency magnetic properties fabricated by multi-stage decarburizing and cold rolling

Ultrathin ternary PtNiGa nanowires for enhanced oxygen reduction reaction

Achieving high activity and durability for the oxygen reduction reaction (ORR) with an ultra-low amount of platinum is significant to promote the widespread application of proton exchange membrane fuel cells (PEMFCs). Here we report a new ultrathin (∼1 nm) ternary PtNiGa alloy nanowires (PtNiGa NWs) electrocatalyst, in which the presence of gallium (Ga) enhances the oxidation resistance of platinum (Pt) and nickel (Ni) and suppresses the dissolution of Ni. The mass and specific activities of PtNiGa NWs are about 11.2 and 7.6 times higher than those of commercial Pt/C catalysts for ORR. Moreover, the mass activity of PtNiGa/C NWs nanocatalyst decreased only by 12.8% and largely retained its electrochemical surface area (ECSA) after 10,000 potential cycles, compared with 38% loss of ECSA for commercial Pt/C catalyst. Therefore, this work provides a general guideline for preparing ternary alloy electrocatalysts and enhancing the activity and stability of the cathode ORR reaction of PEMFCs.

Intermediate annealing and strong cube texture of Ni-5at.%W alloy thin substrates for YBCO coated conductors

In this work, a series of studies have been carried out on ultra-thin Ni-5at%W (Ni5W) alloy substrates used for the coated conductors. The ultra-thin Ni5W alloy substrate can be fabricated for the large square REBCO film with a size of over 40 mm × 40 mm, which is normally used in scenarios to support a magnetic field in a specific area. To obtain a stronger recrystallized cubic texture, the intermediate annealing was added to optimize the rolling texture during the rolling process of the Ni5W alloy substrate. A typical copper-type rolling texture was obtained in the substrate which intermediate annealed at 96.25%, and the cube texture reached 97.6% after annealing recrystallization. Moreover, The deformation and recrystallization of 40 μm thick Ni-5at%W (Ni5W) alloy thin substrates were investigated by the quasi-in situ method. The fabrication of ultra-thin Ni5W substrates increases the potential of miniaturizing lightweight coated conductors, which helps to further promote and accelerate the manufacturing process of the entire coated conductor strip.