Advanced Powder Materials最新文献

Excessive emission of carbon dioxide (CO₂) has posed an imminent threat to human's environment and global prosperity. To achieve a sustainable future, solid oxide electrolysis cell (SOEC), which can efficiently combine CO₂ reduction reaction (CO₂RR) and renewable energy storage, has become increasingly attractive owing to its unique functionalities. Additionally, symmetrical SOEC (SSOEC) has been considered as one of the most versatile cell configurations due to its simplified process, high compatibility, and low cost. However, the electrode material requirements become very demanding since efficient catalytic-activities are required for both CO₂RR and oxygen evolution reaction (OER). Herein, we demonstrate a novel high-entropy perovskite type symmetrical electrode Pr_0.5Ba_0.5Mn_0.2Fe_0.2Co_0.2Ni_0.2Cu_0.2O_3-δ (HE-PBM) for SSOEC. B-site doping of transition metals such as Mn, Fe, Co, Ni, and Cu in HE-PBM anode has been found to strongly accelerate the OER in the anode. Moreover, the presence of in-situ formed Fe–Co–Ni–Cu quaternary alloy nanocatalysts from HE-PBM cathode under reducing atmosphere has resulted in superior catalytic-activity towards CO₂RR. The faster kinetics are also reflected by the significantly low polarization resistance of 0.289 ​Ω⋅cm² and high electrolysis current density of 1.21 ​A⋅cm⁻² for CO₂RR at 2.0 ​V and 800 ​°C. The excellent electrochemical performance and stability demonstrate that the high-entropy perovskite material is a promising electrode material in SSOEC for efficient and durable CO₂RR.

A new type of grain-interior planar defect in a ceramic phase in TiC doped cemented tungsten carbides was discovered. It is unique in that the monolayers of metal atoms exist stably in ceramic grains. The planar defects were induced by the ordered heteroatoms distributing on certain crystal planes of the matrix, which are distinct from the known planar defects such as phase-, grain-, and twin-boundaries, stacking faults, and complexions. Detailed characterization on the atomic scale was performed for the composition, structure, and crystallography of the planar defects, and their energy state and stability were evaluated by modeling. It was found that the Ti monolayer assists nucleation of the new WC crystal along the normal direction to its basal plane. Due to the disturbance of the heteroatom layer, the deposition of W and C atoms deviates from the regular sites occupied in the perfect crystal lattice, resulting in variations of the W–C arrangement in the grain structure. Experiments confirmed that tailoring the distribution density of the planar defects could give the best comprehensive mechanical performance with simultaneously outstanding strength and fracture toughness in the materials containing the grain-interior planar defects. This study provides a new strategy to greatly enhance the mechanical properties of materials by introducing and tailoring planar defects in the grain interiors.

Sulfide-based all-solid-state batteries (ASSBs) exhibit unparalleled application value due to the high ionic conductivity and good processability of sulfide solid electrolytes (SSEs). Carbon-based conductive agents (CAs) are often used in the construction of electronic conductive networks to achieve rapid electron transfer. However, CAs accelerate the formation of decomposition products of SSEs, and their effects on sulfide-based ASSBs are not fully understood. Herein, the effect of CAs (super P, vaper-grown carbon fibers, and carbon nanotubes) on the performance of sulfide-based ASSBs is investigated under different cathode active materials mass loading (8 and 25 ​mg·cm⁻²). The results show that under low mass loading, the side reaction between the CAs and the SSEs deteriorates the performance of the cell, while the charge transfer promotion caused by the addition of CAs is only manifested under high mass loading. Furthermore, the gradient design strategy (enrichment of CAs near the current collector side and depletion of CAs near the electrolyte side) is applied to maximize the benefits of CAs in electron transport and reduce the adverse effects of CAs. The charge carrier transport barrier inside the high mass loading electrode is significantly reduced through the regulation of electronic conductivity. Consequently, the optimized electrode achieves a high areal capacity of 5.6 ​mAh·cm⁻² at high current density (1.25 ​mA·cm⁻², 0.2 ​C) at 25 °C with a capacity retention of 87.85% after 100 cycles. This work provides a promising way for the design of high-mass loading electrodes with practical application value.

Metal selenides have been explored as promising sodium storage materials owing to their high theoretical capacity. However, sluggish Na⁺ diffusion and low electronic conductivity of selenides still hinder their practical applications. Herein, FeSe_2-xS_x microspheres have been prepared via a self-doping solvothermal method using NH₄Fe(SO₄)₂ as both the Fe and S source, followed by gas phase selenization. The density functional theory calculation results reveal that S doping not only improves the Na adsorption, but also lower the diffusion energy barrier of Na atoms at the S doping sites, at the same time enhance the electronic conductivity of FeSe_2-xS_x. The carbon-free nature of the FeSe_2-xS_x microspheres results in a low specific surface area and a high tap density, leading to an initial columbic efficiency of 85.6%. Compared with pure FeSe₂, such FeSe_2-xS_x delivers a high reversible capacity of 373.6 mAh·g⁻¹ at a high current density of 5 ​A·g⁻¹ after 2000 cycles and an enhanced rate performance of 305.8 mAh·g⁻¹ at even 50 ​A·g⁻¹. Finally, the FeSe_2-xS_x//NVP pouch cells have been assembled, achieving high energy and volumetric energy densities of 118 ​Wh·kg⁻¹ and 272 ​mWh·cm⁻³, respectively, confirming the potential of applications for the FeSe_2-xS_x microspheres.

It is of great importance to design highly active and stable electrocatalysts with low Pt loading to improve the sluggish kinetics of oxygen reduction reaction (ORR) for fuel cells. Herein, we report an epitaxial growth of a Pt–Pd bimetallic heterostructure with a Pt loading as low as 8.02 ​wt%. Both experimental studies and theoretical calculations confirm that the heterointerfaces play a major role in charge redistribution, which accelerates electron transfer from Pd to Pt, contributing to downshifting the d-band center of Pd and consequently greatly weakening the O adsorption energy for a critical optimal adsorption configuration of O∗ on the heterointerface. In particular, the adsorbed O∗, an intermediate in a bridge mode between adjacent Pt and Pd atoms, has a relative low adsorption energy, which easily forms H₂O to escape for releasing the active sites toward ORR. The Pt–Pd heterostructured catalyst presents the highest mass activity of 6.06 A·mg⁻¹_Pt among all reported Pt–Pd alloyed or composited catalysts, which is 26.4 times of the sample Pt/C (0.23 A·mg⁻¹_Pt). Further, the fuel cell assembled by the electrocatalyst shows a current density of 1.23 ​A·cm⁻² at 0.6 ​V and good stability for over 100 ​h.

Lithium metal batteries (LMBs) with ultra-high theoretical energy densities are regarded as excellent candidates for the next energy storage devices. Unfortunately, there are many factors can cause the temperature of LMBs to exceed a safe range and trigger thermal runaway. Countless effort has been invested in designing safe components of batteries to realize the application of LMBs. However, most studies only focus on one single aspect since there is no uniform metrics for evaluating the safety of LMBs. Herein, this review comprehensively summarizes all the trigger factors of thermal runaway and proposes the complete safety metrics of LMBs. A comprehensive overview of the development of safe LMBs is provided to discuss the gap between studies and practical applications. Finally, the future directions of academic research are proposed according to the challenges existing in current studies.

Water is considered to be an inhibitor of CO oxidation. The mechanism of retarding the reaction is thought to contribute to the practical application of CO oxidation, which is investigated by constructing the coupling of Au nanoparticles and defective CuO to form metal-support interactions (MSI) and oxygen vacancies (OVs). The introduction of Au forms a new CO adsorption site, which successfully solves the competitive adsorption problem of CO with H₂O and O₂. Due to the coupling of MSI and OVs, the reduced ability of catalyst and the activation and migration ability of oxygen are enhanced simultaneously. Au-CuO has the ability to oxidize CO at room temperature with high stability under a humid environment. Theoretical calculation confirmed the competitive adsorption and the influence of MSI and OVs coupling on the catalyst performance. The mechanism of water resistance in CO catalytic oxidation was also explained.

Despite the fact that low-dimensional carbons (LDCs, 1D/2D) materials are very interesting due to their intriguing electrical properties, we still attempt to enrich them by high N-content in order to enjoy their electro-applications. We here report a template-free synthesis of 1D/2D LDC with high N content (>40 ​at%) and tunable aspect ratios from molecular formamide (FA). The 1D/2D LDC is in polyaminoimidazole as confirmed by pair distribution function analysis, and 1D growth mode can be altered to 2D by simply adding a 2D-guiding molecule of melamine. Electrochemical properties of the LDC can be finely tuned by adjusting the solvothermal temperature and melamine dosage. It is revealed that the optimal 2D LDC delivers superior O₂-to-H₂O₂ yield (687.2 ​mmol·g⁻¹⋅h⁻¹) and Faradic efficiency (87.5%). Considering the heavy N content and high adjustability of aspect ratio, the FA-derived LDCs potentially open new synthesis routes for structural carbon materials for broad electrochemical applications.

Laser powder bed fusion (LPBF) has made significant progress in producing solid and porous metal parts with complex shapes and geometries. However, LPBF produced parts often have defects (e.g., porosity, residual stress, and incomplete melting) that hinder its large-scale industrial commercialization. The LPBF process involves complex heat transfer and fluid flow, and the melt pool is a critical component of the process. The melt pool stability is a critical factor in determining the microstructure, mechanical properties, and corrosion resistance of LPBF produced metal parts. Furthermore, optimizing process parameters for new materials and designed structures is challenging due to the complexity of the LPBF process. This requires numerous trial-and-error cycles to minimize defects and enhance properties. This review examines the behavior of the melt pool during the LPBF process, including its effects and formation mechanisms. This article summarizes the experimental results and simulations of melt pool and identifies various factors that influence its behavior, which facilitates a better understanding of the melt pool's behavior during LPBF. This review aims to highlight key aspects of the investigation of melt pool tracks and microstructural characterization, with the goal of enhancing a better understanding of the relationship between alloy powder-process-microstructure-properties in LPBF from both single- and multi-melt pool track perspectives. By identifying the challenges and opportunities in investigating single- and multi-melt pool tracks, this review could contribute to the advancement of LPBF processes, optimal process window, and quality optimization, which ultimately improves accuracy in process parameters and efficiency in qualifying alloy powders.

Optical temperature sensors, which can accurately detect temperature in biological systems, are crucial to the development of healthcare monitoring. To challenge the state-of-art technology, it is necessary to design single luminescence center doped materials with multi-wavelength emission for optical temperature sensors with more modes and higher resolution. Here, an Er³⁺ single-doped KYF₄ nanocrystals glass ceramic with an obvious thermochromic phenomenon is reported for the first time, which shows a different temperature-dependent green, red, and near-infrared luminescence behavior based on thermal disturbance model. In addition, Er³⁺ single-doped GC fiber was drawn and fabricated into multi-mode optical fiber temperature sensor, which has superior measured temperature resolution (＜0.5 ​°C), excellent detection limit (0.077 ​°C), and high correlation coefficient (R²) of 0.99997. More importantly, this sensor can monitor temperature in different scenarios with great environmental interference resistance and repeatability. These results indicate that our sensor shows great promise as a technology for environmental and healthcare monitoring, and it provides a route for the design of optical fiber temperature sensors with multi-mode and high resolution.