Rare Metals最新文献

The limited biocompatibility, high preparation costs, and non-reusability of noble metal surface-enhanced Raman scattering (SERS) substrates impede their large-scale application. Consequently, the development of non-noble metal substrates with excellent SERS performance remains a priority. Although quasi-metal SERS substrates represented by carbides have demonstrated remarkable SERS performance, their enhancement capabilities still require further improvement. In this study, the SERS performance of tungsten carbide (WC) substrates was enhanced by doping with tantalum (Ta) elements. The WC doped with 2 wt% Ta (WC-2T) exhibited a superior enhancement effect for probe molecules like rhodamine 6G (R6G), crystal violet, methylene blue, and malachite green compared to the undoped WC (WC-0T), with the enhancement factor for R6G molecules more than doubling. The excellent SERS performance of WC-2T can be attributed to its higher adsorption energy for probe molecules and a more efficient charge transfer process between the probe molecules. Additionally, the SERS effect of WC-2T remained robust even when exposed to strong acids and alkalis. This study successfully enhanced the SERS activity of WC via doping modification, providing a strategy for optimizing carbide quasi-metal SERS-active materials.

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Complete collection of target fluids and effective capture of biomolecules are essential when designing and fabricating sensor electrodes. Assembling a conductive metal–organic framework (MOF) film onto a high-surface-area porous aerogel to create a three-dimensional (3D) hierarchically ordered structure represented an effective strategy for fabricating sensor electrodes for body fluid detection. In this study, high-precision, confined growth of a self-assembled Cu-HHTP layer on an aerogel assisted by atomic layer deposition was employed to fabricate a hierarchical 3D-ordered metal–organic aerogel (MOA) electrode. This structure comprises two components: a conductive MOF thin film with abundant exposed active sites and a flexible 3D aerogel featuring through-holes with strong adsorption capacity, thereby enhancing liquid confinement and promoting biomolecule adsorption. This approach combines the aerogel’s high flexibility and liquid adsorption ability with the conductive network of the Cu-HHTP film, thereby enabling an effective dopamine (DA) sensor. The sensor based on the 3D-ordered MOA electrode exhibits high sensitivity, with a detection limit of 1.19 μM, along with excellent selectivity, stability, reproducibility, and strong anti-interference capability, as evidenced by negligible deviations in DA measurements across aqueous (H₂O) and fetal bovine serum (FBS) samples. A proof-of-concept test using human urine produces a pronounced response, confirming the sensor’s practical feasibility.

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To mitigate capacity fading and enhance the thermal stability of ultrahigh-nickel cathode materials under high voltage, this study designs and synthesizes a gradient Mo-modified LiNi_0.91Co_0.045Mn_0.045O₂ cathode with grain crystallographic orientation via a dry method. In situ X-ray diffraction characterizations and first-principles calculations reveal that the structural stability of the Mo-modified cathode at high voltage is significantly enhanced by stabilizing the oxygen framework. Additionally, the radially distributed grains facilitate lithium-ion diffusion during charge–discharge cycles. Consequently, after 3 wt% MoO₃ modification (NCM@3Mo), the cathode achieves an ultrahigh energy density of 919 Wh kg⁻¹ at 0.1C, with energy density retention improving from 53% to 80% after 200 cycles. Even at a high current density of 5C, a reversible discharge capacity of 198.1 mAh g⁻¹ is maintained. Moreover, the phase transformation temperature from spinel to rock salt of the delithiated Mo-modified cathode increases by 50 °C during heating. This work presents a comprehensive and robust strategy for the design and synthesis of layered cathode materials that preserve structural integrity at high voltages, thereby meeting the stringent requirements for ultrahigh energy density and enhanced safety in battery systems.

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Layered V₂O₅·H₂O (vanadium pentoxide hydrate) is a highly promising cathode material for aqueous zinc-ion batteries owing to its large interlayer space, variable V valence states, and unique interlayer H₂O. However, the low electronic conductivity and easily exfoliated lattice layers lead to its poor charge transport kinetics and lattice stability. In this regard, we develop a ternary transition metal ions pre-intercalation strategy, where ternary Ni/Mn/Cu cations are successfully pre-intercalated into V₂O₅·H₂O by one-step hydrothermal method. It is revealed that Mn cation activates the additional Mn⁴⁺/Mn³⁺ redox reaction, and ternary Ni/Mn/Cu cations cause the strong ion column effect, induce the highest p-band center of O, and improve the electrical conductivity, thus simultaneously enhancing the lattice stability and charge transport kinetics. As a result, the energy density of 391 Wh kg⁻¹ at 0.1 A g⁻¹ and the high-rate capability with a capacity of 240 mAh g⁻¹ at 3 A g⁻¹ after 600 cycles are achieved. Besides, the electrochemical reaction mechanism is revealed to be H⁺ intercalation at high potentials, and followed Zn²⁺ intercalation at low potentials, and Zn²⁺ intercalation contributes most of the capacity (> 65%) and H⁺ intercalation promotes the optimization of electrochemical performance.

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Self-template transformations are widely used for preparation of lanthanide (Ln³⁺) based nanoparticles with tunable porosity and composition, considering of their outstanding performance in optical, drug delivery and bio-imaging. However, it is still a major challenge to characterize the crystallization process, morphology and composition changes of these nanostructures in atomic scale and three-dimensional (3D). In this paper, we investigate the transformation of amorphous precursor to porous Y₂O₃:Eu³⁺ nanocrystals with advanced microscopy techniques. The morphology changes and compositions under different temperatures are identified through in-situ microscopy. The porous structures in 3D is clearly studied via electron tomography. Insights from this research are of broader interest for the class of transformation reactions, which will definitely shed light on the synthesis of complex nanostructures.

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The transformation of amorphous precursor to porous Y₂O₃:Eu³⁺ nanocrystals was investigated via in-situ microscopy and electron tomography in 3D.

Tin dioxide (SnO₂) with a high theoretical specific capacity of 1494 mAh g^–1 is a promising candidate anode material for lithium storage. However, the shortcomings of serious volume expansion and low conductivity limit its wide application. Herein, coaxial nano-multilayered C/SnO₂/TiO₂ composites were fabricated via layer-by-layer self-assembly of TiO₂ and SnO₂-gel layers on the natural cellulose filter paper, followed by thermal treatment under a nitrogen atmosphere. Through engineering design of the assembly process, the optimal C/SnO₂/TiO₂ composite features five alternating SnO₂ and TiO₂ nanolayers, with TiO₂ as the outside shell (denoted as C/TSTST). This unique structure endows the C/TSTST with excellent structural stability and electrochemical kinetics, making it a high-performance anode for lithium-ion batteries (LIBs). The C/TSTST composite delivers a high reversible capacity of 676 mAh g⁻¹ at 0.1 A g⁻¹ after 200 cycles and retains a capacity of 504 mAh g⁻¹ at 1.0 A g⁻¹, which can be recovered to 781 mAh g⁻¹ at 0.1 A g⁻¹. The significantly enhanced electrochemical performance is attributed to the hierarchical hybrid structure, where the carbon core combined with coaxial TiO₂ nanolayers serves as a structural scaffold, ameliorating volume change of SnO₂ while creating abundant interfacial defects for enhanced lithium storage and rapid charge transport. These findings are further demonstrated by the density functional theory (DFT) calculations. This work provides an efficient strategy for designing coaxial nano-multilayered transition metal oxide-related electrode materials, offering new insights into high-performance LIBs anodes.

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The selective semi-hydrogenation of phenylacetylene (PA) to styrene (ST) represents a critical industrial reaction, essential for producing polymer-grade styrene. Yet, achieving high selectivity at high conversions remains fundamentally challenging due to competing over-hydrogenation. Here we report an atomic-scale approach for encapsulating ultrafine PtCu (Platinum, Copper) bimetallic nanoclusters (NCs) within the microporous TS-1 zeolite matrix through a ligand-assisted hydrothermal strategy. Remarkably, the as-synthesized PtCu@TS-1 catalyst exhibited an unprecedented turnover frequency (TOF) of 2006.7 h⁻¹ and a superior styrene yield of 87.7%, significantly surpassing conventional Pt-based catalysts. Advanced characterization and in situ spectroscopy revealed that electron-rich Pt sites, induced by electron transfer from Cu in confined PtCu ensembles, substantially lower the activation barrier for hydrogen dissociation, accelerating selective hydrogenation. Moreover, the atomic confinement effect within the zeolite structure effectively modulates intermediate adsorption and accelerates product desorption, thus overcoming the selectivity-activity trade-off. This study introduces a generalizable atomic-level catalyst design principle, highlighting the immense potential of quantum-sized bimetallic clusters within porous materials for precisely tuning reaction selectivity and activity.

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Bacterial infections, as a global public health problem, are a serious threat to human life and health safety with the significant increase of antibiotic-resistant bacteria. Polyoxometalates (POMs), with their unique structure, and high biocompatibility and designability, have received widespread attention in the field of antimicrobials, showing great potential, which has led to the design of various strategies to fabricate POM-based composites with antimicrobial properties. In this paper, the preparation strategies based on the biological components of POMs and their organic derivatives are reviewed, and the latest progress in the design and preparation of various antimicrobial POM-based materials and the practical application of POM antibacterial materials in some fields are introduced in detail from four aspects: pure inorganic POMs, POM-based materials bound to organic small molecules, POM-based materials bound to organic biomolecules, and POM-based nanocomposites. In addition, the potential antimicrobial mechanisms of POMs are summarized, and the significant advantages of POMs in collaboration with antibiotics against drug-resistant bacteria are demonstrated. The limitations and prospects of current research are also discussed. It is hoped that this review can help researchers to keep abreast of the development of POM-based antimicrobial materials, thus promoting their development, application, and large-scale production.

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