Rare Metals最新文献

Abstract

The inherent safety, high theoretical specific capacity and low raw material cost of aqueous batteries make them potential candidates in large-scale energy storage. However, uncontrolled dendrite growth, parasitic reactions and sluggish mass transfer on the anode-electrolyte interface are the main challenges restricting the application prospect of aqueous zinc-ion batteries. In general, eukaryotic cells utilize specific ion channels to achieve ion migration with the merits of low energy consumption and rapid speed. Herein, migrating the concept of ion channels to aqueous batteries, a crown species encapsulated zeolitic imidazolate framework (ZIF) interfacial layer (denoted as ZIF@Crown) was ex situ decorated onto the Zn anode. Similar to biological ion channels, the ZIF@Crown layer can homogenize the distribution of Zn²⁺ on the anode, accelerate the desolvation of hydrated Zn²⁺ and reduce the energy barrier for Zn²⁺ deposition, which were verified by theoretical calculations and experimental characterizations. Benefiting from these efficacious modulation mechanisms, the Zn@ZIF@Crown symmetrical cell could achieve a long calendar life of over 1900 h and the Zn@ZIF@Crown||Cu also sustained 600 cycles with a high Coulombic efficiency (97%). Furthermore, the full cells containing ZIF@Crown layer exhibit desirable electrochemical performance. This work provides an innovative avenue toward the optimization of aqueous batteries via bionic interfacial engineering.

Graphical abstract

One-dimensional nanomaterials with hollow structures could provide large space for ion storage and charge accumulation. Herein, TiO₂/MoSe₂-Carbon nanotube composite (NT) materials were designed and fabricated by the template method and the chelation coordination reaction. The stability and conductivity were improved by the presence of titanium and hollow tubular-architecture carbon in the whole structure. As a result, the as-prepared TiO₂/MoSe₂-Carbon hybrid achieved a high-rate performance of 760.0 mAh·g⁻¹ at a current density of 0.1 A·g⁻¹, while still obtaining stability after 300 charge/discharge cycles. The enhancement of the lithium storage capacity mainly contributed to the acceleration of the electron conductivity and the storage kinetics. Moreover, the hollow structure reduced the volume strain and stress caused by the rapid insertion and removal of lithium ions, which ensured the favorable stability of lithium storage. The experiment shows that the kinetic of the TiO₂/MoSe₂-carbon hybrid during the lithium storage process is dominated by the pseudocapacitance mechanism. This work provides a new idea and scheme for the design and preparation of hierarchical nanotube composite electrode materials.

Graphic Abstract

The rise in gas leakage incidents underscores the urgent need for advanced gas-sensing platforms with ultra-low concentration detection capability. Sensing gate field effect transistor (FET) gas sensors, renowned for the gas-induced signal amplification without directly exposing the channel to the ambient environment, play a pivotal role in detecting trace-level hazardous gases with high sensitivity and good stability. In this work, carbon nanotubes are employed as the conducting channel, and yttrium oxide (Y₂O₃) is utilized as the gate dielectric layer. Noble metal Pd is incorporated as a sensing gate for hydrogen (H₂) detection, leveraging its catalytic properties and unique adsorption capability. The fabricated carbon-based FET gas sensor demonstrates a remarkable detection limit of 20 × 10^–9 for H₂ under an air environment, enabling early warning in case of gas leakage. Moreover, the as-prepared sensor exhibited good selectivity, repeatability, and anti-humidity properties. Further experiments elucidate the interaction between H₂ and sensing electrode under an air/nitrogen environment, providing insights into the underlying oxygen-assisted recoverable sensing mechanism. It is our aspiration for this research to establish a robust experimental foundation for achieving high performance and highly integrated fabrication of trace gas sensors.

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Room-temperature sodium-sulfur batteries are promising grid-scale energy storage systems owing to their high energy density and low cost. However, their application is limited by the dissolution of long-chain sodium polysulfides and slow redox kinetics. To address these issues, a cobalt single-atom catalyst with N/O dual coordination was derived from a metal-organic framework precursor (denoted as Co–N₂O₂/MOFc) for sulfur storage. Theoretical analysis demonstrates that, compared with the Co–N₄ structure, the introduction of oxygen atoms can further tune the d-electron density of Co atoms via the coordinative effect, which enhances d-p hybridization after Na₂S_x adsorption on Co–N₂O₂/MOFc. This leads to higher adsorption energy for Na₂S_x, lower Gibbs free energy for the rate-limiting process and a decreased Na₂S decomposition energy barrier, thereby promoting the polysulfide conversion reaction kinetics. When used as a sulfur host, the Co–N₂O₂/MOFc/S cathode exhibits excellent performance with a capacity of 590 mAh·g⁻¹ (983 mAh·g⁻¹ normalized by the sulfur mass) after 100 cycles at 0.1 A·g⁻¹ and an excellent rate capability of 350 mAh·g⁻¹ at 10 A·g⁻¹.

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Dual-element-doped Co-free Ni-rich LiNiO₂-based cathodes demonstrate great potential for high-energy lithium-ion batteries (LIBs). Nevertheless, they suffer from serious Li⁺/Ni²⁺ mixing, irreversible phase transitions, structural degradation and side reactions at the cathode/electrolyte interface. Herein, W is purposively introduced into LiNi_0.9Mn_0.05Ti_0.025Al_0.025O₂ to engineer rock-salt Li_4+xNi_1-xWO₆ stabilized LiNi_0.9Mn_0.035Ti_0.025Al_0.025W_0.015O₂ (LNMTAWO) cathode. In situ characterizations, together with electrochemical analysis, demonstrate that Mn, Ti and Al can effectively enhance the reversibility of phase transitions, stabilize the TM–O bonds under high voltage and relieve voltage decay. The rock-salt Li_4+xNi_1-xWO₆ can prevent the overgrowth of grain size, avoid the exposure of active materials into electrolytes and decrease the side reaction. Benefitting from the dual-element synergistic effects, the LNMTAWO cathode offers high reversible capacities of 228.7 and 150.8 mAh·g⁻¹ at 0.2C and 5C, respectively, and contributes a high reversible capacity of 171.4 mAh·g⁻¹ at 0.5C after 200 cycles (voltage delay: 5 mV) and 88.4 mAh·g⁻¹ at 10C after 500 cycles. Such design of rock-salt structure symbiotically grown on Ni-rich cathodes by introducing high-valence elements would provide rational guidelines on engineering high-energy Co-free Ni-rich LIB cathodes.

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Flexible thermoelectric thin films offer a promising avenue for the development of portable and sustainable flexible power supplies. However, a lack of thin films with excellent performance restricts their application in flexible thermoelectric devices. In this study, high-performance BiSbTe films are successfully prepared using a combination of magnetron sputtering and thermal diffusion. By optimizing carrier concentration to ~ 4.47 × 10¹⁹ cm⁻³ and simultaneously realizing high carrier mobility of > 120 cm²·V⁻¹·s⁻¹, an impressive room-temperature power factor of 24.13 μW·cm⁻¹·K⁻² is achieved in a Bi_0.4Sb_1.6Te₃ thin film. The flexible Bi_0.4Sb_1.6Te₃ thin film also demonstrates excellent bending resistance and stability (ΔR/R₀ < 5%, ΔS/S₀ < 5%, and ΔS²σ/S₀²σ₀ < 10%) after 1000 bending cycles at a minimum bending radius of 6 mm. A flexible thin-film thermoelectric device assembled with p-type Bi_0.4Sb_1.6Te₃ legs achieves a remarkable power output of ~ 82.15 nW and a power density of ~ 547.68 μW·cm⁻² under a temperature difference of 20 K.

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The rapid evolution of hypersonic vehicle technologies necessitates robust thermal protection systems capable of withstanding extreme oxidative ablation. This study introduces a novel gradient-architected ZrB₂–MoSi₂–SiC dense layer embedded within a lightweight three-dimensional (3D) needled carbon fiber composite. Utilizing the volatility of ethanol and polycarbosilane, the ceramic slurry is selectively infused into targeted regions of the fibrous structure, optimizing the ZrB₂ to MoSi₂ ratio to enhance performance. The resulting dense layer exhibits exceptional emissivity, surpassing 0.90 in the 1–3 μm range and exceeding 0.87 in the 2–14 μm range. Moreover, it demonstrates remarkable oxidative ablation resistance. Specifically, at an optimized ZrB₂ to MoSi₂ ratio of 6:4, the dense layer achieves a minimal linear ablation rate of 0.015 μm·s⁻¹ under a 1.5 MW·m⁻² oxyacetylene flame for 1000 s. Even after exposure to oxyacetylene ablation at surface temperatures of approximately 1750 °C for 1000 s, the dense layer retains its structural integrity, highlighting its enduring oxidation resistance. The incorporation of MoSi₂ not only enhances emissivity but also fortifies the ZrO₂ and SiO₂ oxide layers, crucial for environments with elevated oxygen levels, thereby mitigating the active oxidation of SiC. This combination of high emissivity and long-term oxidation resistance at ultra-high temperatures positions the ZrB₂–MoSi₂–SiC dense layer as an exceptionally promising candidate for advanced thermal protection in hypersonic vehicles.

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With the rapid development of artificial intelligence, magnetocaloric materials as well as other materials are being developed with increased efficiency and enhanced performance. However, most studies do not take phase transitions into account, and as a result, the predictions are usually not accurate enough. In this context, we have established an explicable relationship between alloy compositions and phase transition by feature imputation. A facile machine learning is proposed to screen candidate NiMn-based Heusler alloys with desired magnetic entropy change and magnetic transition temperature with a high accuracy R²≈0.98. As expected, the measured properties of prepared NiMn-based alloys, including phase transition type, magnetic entropy changes and transition temperature, are all in good agreement with the ML predictions. As well as being the first to demonstrate an explicable relationship between alloy compositions, phase transitions and magnetocaloric properties, our proposed ML model is highly predictive and interpretable, which can provide a strong theoretical foundation for identifying high-performance magnetocaloric materials in the future.

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Microbiologically influenced corrosion and bacterial infection lead to serious losses to human production and life. Developing alloys with inherent antibacterial properties is a vital way to solve the above issues. However, the widely used Cu-containing stainless steels show insufficient antimicrobial properties and relatively low yield strengths, which further limit their application in extreme service environments. Based on the design concept of high-entropy alloys (HEAs), a novel low-cost Co-free CrFeNi_0.5Cu_0.3 HEA with an optimal combination of antibacterial and mechanical properties was designed and prepared. This alloy comprises triple-phase structures, including FeNi-rich face-centered cubic (FCC1), Cu-rich FCC2 and FeCr-rich body-centered cubic (BCC). The antibacterial rate of this HEA is up to 99.99% against Escherichia coli, which is far superior to that of classic 304 Cu-bearing stainless steel (304-Cu SS) and the most reported antibacterial alloys. In addition, the HEA exhibits excellent mechanical properties with a tensile strength of 1032 MPa and yield strength of 842 MPa, far surpassing the corresponding values of 304-Cu SS (i.e., 528 MPa and 210 MPa, respectively). These findings provide new insights for the development of low-cost and high-performance antibacterial alloys.

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Owing to their exceptional properties, high-entropy alloys (HEAs) and high-entropy materials have emerged as promising research areas and shown diverse applications. Here, the recent advances in the field are comprehensively reviewed, organized into five sections. The first section introduces the background of HEAs, covering their definition, significance, application prospects, basic properties, design principles, and microstructure. The subsequent section focuses on cutting-edge high-entropy structural materials, highlighting developments such as nanostructured alloys, grain boundary engineering, eutectic systems, cryogenic alloys, thin films, micro-nano-lattice structures, additive manufacturing, high entropy metallic glasses, nano-precipitate strengthened alloys, composition modulation, alloy fibers, and refractory systems. In the following section, the emphasis shifts to functional materials, exploring HEAs as catalysts, magneto-caloric materials, corrosion-resistant alloys, radiation-resistant alloys, hydrogen storage systems, and materials for biomedicine. Additionally, the review encompasses functional high-entropy materials outside the realm of alloys, including thermoelectric, quantum dots, nanooxide catalysts, energy storage materials, negative thermal expansion ceramics, and high-entropy wave absorption materials. The paper concludes with an outlook, discussing future directions and potential growth areas in the field. Through this comprehensive review, researchers, engineers, and scientists may gain valuable insights into the recent progress and opportunities for further exploration in the exciting domains of high-entropy alloys and functional materials.

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