Rare Metals最新文献

Electrocatalytic CO₂ reduction reaction (CO₂RR) to produce multicarbon (C₂₊) products over Cu-based catalysts represents an ideal approach for renewable energy storage and carbon emissions reduction. The Cu⁰/Cu^δ+ interfaces are widely recognized as crucial sites that promote C–C coupling and enhance the generation of C₂₊ products. However, a major challenge arises from the tendency of Cu^δ+ active sites within Cu⁰/Cu^δ+ interfaces to undergo reduction to Cu⁰ during the CO₂RR process, leading to a decline in catalytic performance. Hence, it is crucial to establish durable Cu⁰/Cu^δ+ interfaces to enhance the conversion of CO₂ to C₂₊ products. In this work, an iodine modification strategy is proposed to prepare a stable Cu@CuI composite catalyst with well-maintained Cu⁰/Cu^δ+ interfaces through a one-step redox reaction between iodine and copper. The optimized Cu@CuI-3 composite catalyst demonstrates an excellent performance in CO₂RR, achieving a Faradaic efficiency of 75.7% for C₂₊ products and a partial current density of 288 mA·cm⁻² at − 1.57 V_RHE in a flow cell. Operando techniques reveal that a numerous persistent Cu^δ+ species exist on the surface of the Cu@CuI-X composite catalyst even after CO₂RR due to the presence of adsorbed iodine ions, which prevent complete reduction of Cu^δ+ species to Cu⁰ owing to their high electronegativity. Density functional theory calculations further verify that adsorbed iodine ions on the surface of Cu@CuI-X serve as charge regulators by adjusting local charge density, thereby facilitating the formation of *CHO intermediates from CO₂ and lowering the energy barriers associated with coupling the *CHO and *CO intermediates during CO₂RR. Consequently, this phenomenon enhances the selectivity toward C₂₊ products during electrocatalytic CO₂ reduction.

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The highly reversible insertion/extraction of large-radius K⁺ into electrode materials remains a tough goal, especially for conversion-type materials. Herein, we design a current collector-integrated electrode (N–CoSe/CoSe₂–C@Cu) as an advanced anode for potassium-ion battery (PIBs). The conductive CoSe/CoSe₂ heterojunction with rich Se vacancy defects, conductive sp² N-doped carbon layer, and the elastic copper foil matrix can greatly accelerate the electron transfer and enhance the structural stability. Consequently, the well-designed N–CoSe/CoSe₂–C@Cu current collector-integrated electrode displays enhanced potassium storage performance with regard to a high capacity (325.1 mAh·g⁻¹ at 0.1 A·g⁻¹ after 200 cycles), an exceptional rate capability (223.5 mAh·g⁻¹ at 2000 mA·g⁻¹), and an extraordinary long-term cycle stability (a capacity fading of only 0.019% per cycle over 1200 cycles at 2000 mA·g⁻¹). Impressively, ex situ scanning electron microscopy (SEM) characterizations prove that the elastic structure of copper foil is merged into the cleverly designed N–CoSe/CoSe₂–C@Cu heterostructure, which buffers the deformation of structure and volume and greatly promotes the cycle life during the potassium/depotassium process.

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Two-dimensional (2D) metallic 1T-CoTe₂ has attracted considerable attention due to its fascinating physical properties and promising applications in electronics and catalysis. However, the production of high-quality 2D 1T-CoTe₂ still remains challenging. Herein, we demonstrate a methodology to realize the facile synthesis of ultrathin, high-quality CoTe₂ flakes with a thickness down to 2.3 nm on mica substrates by an ambient-pressure chemical vapor deposition (CVD) technique. The atomic arrangement is verified by scanning transmission electron microscopy. The theoretical calculations uncover the metallic characteristic of 1T-CoTe₂ in the 2D limit. Remarkably, the CVD-derived 2D metallic CoTe₂ flakes for the hydrogen evolution reaction (HER) catalyst exhibit admirable performance, such as an overpotential of 186 mV at 10 mA·cm⁻², a Tafel slope of 78 mV·dec⁻¹, an exchange current density of 69 μA·cm⁻², and negligible performance degradation after 1000 cycles. These results establish novel approaches for the synthesis and HER application of 2D metallic 1T-CoTe₂.

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Adding numerous dislocations into metallic materials before the forming stage significantly enhances their deformability. However, this beneficial effect of dislocation defects may not have a simple monotonic relationship with increased dislocation density during electroplastic deformation. This is due to the complex interactions among the drifting electrons, dislocations and solute atoms. This study explores the effect of diverse initial dislocation densities on creep deformation during electrically aided creep aging of an aluminum–lithium alloy. Surprisingly, we discovered a threshold value for the dislocation density that affects electroplastic creep, i.e., an enhanced effect from dislocations weakens when exceeding this density threshold (an anomalous response to creep). Microstructural data also reveal that such an anomalous response originates mainly from differences in various dislocation density-tailored configurations, which can influence the dislocation motions and precipitation kinetics of the strengthening T₁ precipitates under the same action of pulsed currents. This study provides important insights into the dislocation density-mediated electroplastic creep of an aluminum–lithium alloy.

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Eco-friendly lead-free tin (Sn)-based perovskites have drawn much attention in the field of photovoltaics, and the highest power conversion efficiency (PCE) of Sn-based perovskite solar cells (PSCs) has been recently approaching 15%. However, the PCE improvement of Sn-based PSCs has reached bottleneck, and an unambiguous guidance beyond traditional trial-and-error process is highly desired for further boosting their PCE. In this work, machine learning (ML) approach based on artificial neural network (ANN) algorithm is adopted to guide the development of Sn-based PSCs by learning from currently available data. Two models are designed to predict the bandgap of newly designed Sn-based perovskites and photovoltaic performance trends of the PSCs, and the practicability of the models are verified by real experimental data. Moreover, by analyzing the physical mechanisms behind the predicted trends, the typical characteristics of Sn-based perovskites can be derived even no relevant inputs are provided, demonstrating the robustness of the developed models. Based on the models, it is predicted that wide bandgap Sn-based PSCs with optimized interfacial energy level alignment could obtain promising PCE breaking 20%. At last, critical suggestions for future development of Sn-based PSCs are provided. This work opens a new avenue for guiding and promoting the development of high-performing Sn-based PSCs.

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Immunotherapy has attracted wide attention because it can not only kill tumor cells but also effectively prevent tumor recurrence. However, due to the poor efficacy of the monotherapy in tumor immunotherapy, combination therapies are needed to enhance their efficacy, such as chemodynamic therapy/immunotherapy, photodynamic therapy/immunotherapy, sonodynamic therapy/immunotherapy and so on. Nanoscale metal–organic frameworks (nMOFs) are widely used for drug delivery because of their rich and variable composition, high drug loading capacity and good biodegradability. Compared with other conventional drug delivery systems (DDSs), nMOFs play more advantageous role in inducing immune cell death of tumor cells and combination therapies. This article focuses on the application of nMOFs in tumor immunotherapy in terms of their use as gatekeepers, supplementary agents and drug carriers, respectively, with the aim of providing some ideas and references for the design of smart nanoscale DDS for tumor immunotherapy.

Bulk nanoporous (np) metallic actuators have attracted increasing attention due to their large strain and low stimulation voltage. However, studies focusing upon the combined effect of composition and structure on the actuation performance of metallic actuators are relatively scarce, and its underlying mechanism needs to be clarified. Herein, a series of bulk np-NiPd samples with different compositions and microstructures were fabricated using a dealloying-coarsening-dealloying strategy and charge-controlled electrochemical dealloying, and the process involves only one component of precursor alloy. It has been found that the np-NiPd cubes show a composition/structure-dependent mechanical property and electrochemical actuation performance. Specially, the np-Ni₇₀Pd₃₀ sample with a homogeneously porous structure and good network connectivity exhibits significantly larger strain amplitude and faster strain rate than other hierarchically porous NiPd samples (np-Ni₅₀Pd₅₀ and np-Ni₂₀Pd₈₀). Moreover, the np-Ni₇₀Pd₃₀ sample demonstrates good actuation stability with high strain retention after hundreds of cycles. Notably, the maximum strain amplitude (1.17%) is even comparable to that of advanced lead-free piezoceramic, and the maximum strain rate exceeds those of many reported metallic actuator materials. Our work indicates that good network connectivity plays a vital role in facilitating large/fast strain response in metallic actuators.

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Developing anode materials with high specific/volumetric capacities, high-rate capability, long-term cycles and low cost is significant for advanced sodium-ion storage. Herein, we report the hybrid TiO₂/graphite (TiO₂/G) anodes for fast (dis)charging sodium-ion storage. Taking advantage of the rapid pseudocapacitive surface-redox on anatase TiO₂ nanoparticles (NPs) and fast [Na(diglyme)_x]⁺ co-intercalation into graphite, the hybrid anodes display excellent rate capabilities. Additionally, the TiO₂ NPs are able to fill into the interspaces among graphite flakes and the graphite provides continuous electron pathways, which largely boosts the volumetric capacities and rate performance. Benefitting from the synergistic effects, the hybrid electrodes display excellent comprehensive electrochemical performance. At the thick-film electrodes (a single-side mass loading of 10 mg·cm⁻²), the hybrid TiO₂/G anode, in a ratio of 40/60 by weight, exhibits high gravimetric and volumetric capacities (71 mAh·g⁻¹/152 mAh·cm⁻³) at a high current density of 20 mA·cm⁻² (2 A·g⁻¹), which are higher than those of the graphite (61 mAh·g⁻¹/121 mAh·cm⁻³), TiO₂ NPs (37 mAh·g⁻¹/72 mAh·cm⁻³) and hard carbon (19 mAh·g⁻¹/23 mAh·cm⁻³) anodes. The TiO₂/G hybrid anodes with excellent comprehensive electrochemical performance display promising potential for high-power sodium-ion batteries and capacitors.

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The recovery and subsequent reuse of heavy metal ions from industrial wastewater are crucial for promoting sustainable development, but they also present significant challenges. In this article, ethylenediaminetetra-acetic dianhydride (EDTAD), which possesses strong metal chelating ability, is covalently attached to MIL-101-NH₂ (Fe), resulting in a significant improvement in the removal rate of heavy metal ions in wastewater. Furthermore, the recovered waste metal ions are transformed into high-performance FeNi₃/NiFe₂O₄@NC dual-functional oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) catalysts. Specifically, FeNi₃/NiFe₂O₄@NC exhibits outstanding OER performance, with only a 264 mV overpotential at 10 mA·cm⁻². Density functional theory (DFT) calculations reveal that the synergistic effect of the FeNi₃/NiFe₂O₄@NC heterostructure can enhance conductivity, optimize the free energy of * to OH* during OER reaction, and promote catalytic reactivity. This work not only improves the removal rate of heavy metal ions but also obtains high-performance catalysts, while providing a new approach for the treatment and secondary utilization of heavy metal ion wastewater as well as the preparation of low-cost catalysts.

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