Rare Metals最新文献

Exploring a new and robust material for proton conduction is of significant importance to the scientific interest and technological importance. Polyoxometalates (POMs) are a class of molecular anion metal oxide clusters with well-defined structures and diverse properties. Therefore, the design and synthesis of a POM-based material for proton conduction is extremely vital. Herein, a dimeric four tartaric acid-bridged tetra-Zr-incorporated arsenotungstate, [NH₂(CH₃)₂]₁₆KH₇[{Zr(tarH) O₂}₄{As₂W₁₉O₆₈}₂]·16H₂O (1) (tarH = tartaric acid), was successfully synthesized via a conventional aqueous method that utilized the tartaric acid ligand protection strategy, and it was systematically characterized by powder X-ray diffraction (PXRD), thermo gravimetric analysis (TGA), infrared (IR), ultraviolet (UV) spectra and energy-dispersive X-ray spectroscopy (EDS). This strategy included an innovative [Zr(tarH)WO₂]₄⁸⁺ core sandwiched by two distorted [As₂W₁₉O₆₈]¹⁶⁻ subunits. The [Zr(tarH)WO₂]₄⁸⁺ core is constituted of four Zr⁴⁺ and four {WO₂} groups, which are linked together by four tartaric acid ligands. Interestingly, the four tartaric acid ligands decorated on Zr⁴⁺ are covalently modified toward the W atoms. Moreover, the impedance measurements demonstrate that 1 has excellent proton conduction properties with the proton conductivity value of 3.82 × 10⁻³ S·cm⁻¹ under 348 K and 95% RH.

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The acceleration of global industrialization and overuse of fossil fuels have caused the release of greenhouse gases and the disruption of the natural nitrogen cycle, leading to numerous energy and environmental problems. In response to the worsening situation, currently, achieving carbon neutrality and the nitrogen cycle is the most urgent task. In this case, reforming modern industrial production is of high importance and a great challenge as well. N-integrated carbon dioxide (CO₂) co-reduction has gained a lot of attention from the scientific community, particularly in recent years, and is considered a promising approach to turn waste into wealth and achieve carbon neutrality and a nitrogen cycle. In this review, a comprehensive review of the catalytic coupling of CO₂ and nitrogenous small molecules (such as N₂, NH₃ and NO_x) for the green synthesis of high-value chemicals is presented, including representative urea, amines, and amides. In these advances, in-depth discussions of C−N coupling are critically evaluated from the standpoints of catalyst design strategies and possible reaction mechanisms, highlighting the key factors and descriptors that affect the catalytic performance. Finally, the remaining challenges and further prospects are also proposed, with the aim of setting the trajectory for future development of green synthesis of high-value-added chemicals.

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Abstract

In this study, Mg-Gd-Y-(Sm)-Zr (GW-(Sm)) alloys were subjected to compression tests at both 293 and 77 K. The effect of Sm addition on the plastic deformation mechanism of Mg-Gd-Y-Zr (GW) alloy was investigated, and a detailed analysis was conducted on the relationships between mechanical responses and the microstructure of the alloys. The findings suggest that dislocation slip plays a predominant role in the plastic deformation of GW-(Sm) alloys. The addition of Sm reduces the stacking fault energy (SFE) of the alloy, which promotes < c + a > slip and inhibits twinning. Meanwhile, Sm plays a role in solution strengthening, causing an elevation in the flow stress of the alloy. At cryogenic temperature (CT), the critical resolved shear stress (CRSS) of dislocation slip is increased, so the dislocation motion requires greater external force. In addition, the extensive crossed twins exhibited in the microstructure, which shorten the dislocation slip path and enhance the grain boundary strengthening. This research contributes to the advancement of plastic deformation theories for magnesium-rare earth (Mg-RE) alloys.

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Acetone is a common volatile organic compound that can cause harm to human health when inhaled in small amounts. Therefore, the development of fast response and low detection limit acetone sensors becomes crucial. In this study, a core-shell spherical TiO₂ sensor with a rich pore structure was designed. This sensor exhibited excellent sensing properties, including higher responsiveness (100 ppm acetone, R_a/R_g = 80), lower detection limit (10 ppb) and short response time (8 s). The problem is that the sensing mechanism between TiO₂ and acetone is not thoroughly analyzed. To gain further insight, the interaction process of TiO₂ core-shell spheres and acetone under varying oxygen content environments was investigated by dynamic testing, X-ray photoelectron spectroscopy, in-situ Fourier transform infrared spectroscopy and gas chromatography-mass spectrometry. The research results show that acetone not only adsorbs on the surface of the material and reacts with adsorbed oxygen, but also undergoes catalytic oxidation reaction with TiO₂ core-shell spheres. Significantly, in high oxygen content environments, acetone undergoes oxidation to form intermediates such as acids and anhydrides that are difficult to desorpt on the surface of the material, thus prolonging the recovery time of the sensor. The discovery of this sensing process will provide some guidance for the design of acetone sensing materials in the future. Meanwhile, this also imparts valuable references and insights for the investigation of the mechanism and application of other sensitive metal oxide materials.

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Zinc perchlorate (Zn(ClO₄)₂) electrolytes have demonstrated favorable low-temperature performance in aqueous zinc-ion batteries (AZIBs). However, the Zn anode encounters serious dendrite formation and parasitic reactions in zinc perchlorate electrolytes, which is caused by the fast corrosive kinetics at room temperature. Herein, a concentrated perchlorate-based electrolyte consisting of 4.0 M Zn(ClO₄)₂ and saturated NaClO₄ solution is developed to achieve dendrite-free and stable AZIBs at room temperature. The ClO₄⁻ participates in the primary solvation sheath of Zn²⁺, facilitating the in situ formation of Zn₅(OH)₈Cl₂·H₂O-rich solid electrolyte interphase (SEI) to suppress the corrosion effect of ClO₄⁻. The Zn anode protected by the SEI achieves stable Zn plating/stripping over 3000 h. Furthermore, the MnO₂||Zn full cells manifest a stable specific capacity of 200 mAh·g⁻¹ at 28 °C and 101 mAh·g⁻¹ at − 20 °C. This work introduces a promising approach for boosting the room-temperature performance of perchlorate-based electrolytes for AZIBs.

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Abstract

Inverted perovskite solar cells (PSCs) have stood out in recent years for their great potential in offering low-temperature compatibility, long-term stability and tandem cell suitability. However, challenges persist, particularly concerning the use of nickel oxide nanoparticles (NiO_x NPs) as the hole transport material, where issues such as low conductivity, impurity-induced aggregation and interface redox reactions significantly hinder device performance. In response, this study presents a novel synthesis method for NiO_x NPs, leveraging the introduction of ammonium salt dopants (NH₄Cl and NH₄SCN), and the solar cell utilizing the doped NiO_x substrate exhibits much enhanced device performance. Furthermore, doped solar cells reach 23.27% power conversion efficiency (PCE) when a self-assembled monolayer (SAM) is further employed. This study provides critical insights into the synthesis and growth pathways of NiO_x NPs, propelling the development of efficient hole transport materials for high-performance PSCs.

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Zinc (Zn)-based alloys have emerged as promising bioresorbable metals for orthopedic implants because of their favorable combination of moderate degradation rates, good mechanical properties, and biocompatibility. In addition, the performance of bone implants relies heavily on their osteointegration ability, which is closely related to the immune responses triggered after implantation. In this study, two Zn-based alloys, Zn–2Cu and Zn–2Cu–0.8Li were developed, to improve the comprehensive properties of Zn implants. The introduction of copper (Cu) and lithium (Li) via alloying improved the hardness and localized corrosion resistance of Zn-based specimens. Both the Zn alloys exhibited enhanced adhesion, proliferation, and osteogenic differentiation behaviors when tested with MC3T3-E1 cells. Importantly, the immune response of RAW264.7, mediated by the two Zn alloys, with pure Zn as a control was systematically investigated. The results demonstrated that the synergistic release of Cu²⁺ and Li⁺ played a pivotal role in promoting the anti-inflammatory and osteoimmunomodulatory properties of degradable Zn. By alloying with Cu and Li, we achieved sequential and sustained ion release, resulting in the synergistic enhancement of osteoimmunomodulation through the modulation of the JAK-STAT signaling pathway. Finally, the Zn-based specimens were evaluated in vivo using rat mandibular defect models. After 8 weeks, the Zn–2Cu–0.8Li group exhibited significantly higher bone regeneration than the Zn–2Cu and pure Zn groups. These findings highlight the beneficial immune response and potential of Zn–Cu–Li alloys as novel biodegradable materials for orthopedic implants.

Grapical abstract

Based on the unique catalytic properties of precious metals, the introduction of precious metals into metal oxide semiconductors will greatly improve the gas-sensitive properties of materials. As a new type of porous material, metal–organic frameworks (MOF) can be used for gas separation and adsorption due to their adjustable pore size and acceptable thermal stability. In this work, the ZIF-71 MOF was synthesized on CuO nanofibers doped with different concentrations of Ru to form a Ru–CuO@ZIF-71 nanocomposite sensor, which was then used for H₂S detection. The sensor shows sensitivity to trace amounts of H₂S gas (100 ppb), and the response is greatly enhanced at the optimal Ru doping ratio and operating temperature. The introduction of the ZIF-71 membrane can significantly increase the selectivity of the sensor while further improving the sensitivity. Finally, the possible sensing mechanism of the Ru–CuO@ZIF-71 sensor was explored. The enhancement of the H₂S gas sensing properties may be attributed to the catalysis of Ru and the formation of the Schottky junction at the Ru–CuO interface. Besides, the calculation based on density functional theory reveals enhanced adsorption capacities of CuO for H₂S after Ru doping. Therefore, the Ru–CuO@ZIF-71 sensor has strong application potential in exhaled gas detection and portable detection of H₂S gas in industrial environments.

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