Advanced Powder Materials最新文献

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.

Sr₂FeCo_0.2Ni_0.2Mo_0.6O_6-δ (SFCNM) and Sr₂FeNi_0.4Mo_0.6O_6-δ (SFNM) were prepared as the hydrogen electrode materials for solid oxide cells (SOCs) and comparatively investigated by density function theory (DFT) and experiments to demonstrate the benefit of Co addition. The reduced SFCNM (R-SFCNM) and SFNM (R-SFNM) contain exsolved Fe–Co–Ni and Fe–Ni nanoparticles, respectively. DFT indicates that Fe–Co–Ni has optimized combination of the d-band center (descriptor of catalyst activity) and adsorption behavior for H₂O, H₂, H, and OH. The cell with SFCNM hydrogen electrode, La_0.8Sr_0.2Ga_0.8Mg_0.2O_3-δ (LSGM) electrolyte, and La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ (LSCF) oxygen electrode (Cell-SFCNM) demonstrates a higher performance than that with an SFNM hydrogen electrode (Cell-SFNM) at temperatures between 700 and 850 °C in both solid oxide fuel cell (SOFC, 3% H₂O-97% H₂/air) and solid oxide electrolysis cell (SOEC, 20% H₂O-80% H₂/air) modes. At 850 and 700 °C, the peak power density is 1.23 and 0.48 ​W·cm⁻² in SOFC mode, while the current density is 1.25 and 0.37 ​A·cm⁻² at 1.3 V in SOEC mode, respectively. The performance degradation rates at 750 °C are 0.17 ​mV·h⁻¹ in SOFC and 0.15 ​mV·h⁻¹ in SOEC modes within 150 ​h, which are improved by Co doping.

In this study, the structural evolution of SiBCN ceramics during crystallization and its effects on oxidation behavior involving different atomic units or formed phases in amorphous or crystalline SiBCN ceramics were analyzed. The amorphous structure has exceptionally high oxidation activity but presents much better oxidation resistance due to its synchronous oxidation of atomic units and homogeneous composition in the generated oxide layer. However, the oxidation resistance of SiBCN ceramic will degrade during the continual crystallization process, especially for the formation of the nanocapsule-like structure, due to heterogeneous oxidation caused by the phase separation. Besides, the activation energy and rate-controlling mechanism of the atomic units and phases in SiBCN ceramics were obtained. The BNC_x (E_a ​= ​145 ​kJ/mol) and SiC_(2-x) (E_a ​= ​364 ​kJ/mol) atomic units in amorphous SiBCN structure can be oxidized at relatively lower temperatures with much lower activation energy than the corresponding BN(C) (E_a ​= ​209 ​kJ/mol) and SiC (E_a ​= ​533 ​kJ/mol) phases in crystalline structure, and the synchronous oxidation of the SiC_(2-x) and BNC_x units above 750 ​°C changes the oxidation activation energy of BNC_x (E_a ​= ​332 ​kJ/mol) to that similar to SiC_(2-x). The heterogeneous oxide layer formed from the nanocapsule-like structure will decrease the activation energy SiC (E_a ​= ​445 ​kJ/mol) and t-BN (E_a ​= ​198 ​kJ/mol).

Emerging energy technologies, aimed at addressing the challenges of energy scarcity and environmental pollution, have become a focal point for society. However, these actualities present significant challenges for modern energy storage devices. Lithium metal batteries (LMBs) have gained considerable attention due to their high energy density. Nonetheless, their use of liquid electrolytes raises safety concerns, including dendritic growth, electrode corrosion, and electrolyte decomposition. In light of these challenges, solid-state batteries (SSBs) have emerged as a highly promising next-generation energy storage solution by leveraging lithium metal as the anode to achieve improved safety and energy density. Metal organic frameworks (MOFs), characterized by their porous structure, ordered crystal frame, and customizable configuration, have garnered interest as potential materials for enhancing solid-state electrolytes (SSEs) in SSBs. The integration of MOFs into SSEs offers opportunities to enhance the electrochemical performance and optimize the interface between SSEs and electrodes. This is made possible by leveraging the high porosity, functionalized structures, and abundant open metal sites of MOFs. However, the rational design of high-performance MOF-based SSEs for high-energy Li metal SSBs (LMSSBs) remains a significant challenge. In this comprehensive review, we present an overview of recent advancements in MOF-based SSEs for LMSSBs, focusing on strategies for interface optimization and property enhancement. We categorize these SSEs into two main types: MOF-based quasi-solid-state electrolytes and MOF-based all solid-state electrolytes. Within these categories, various subtypes are identified based on the combination mode, additional materials, formation state, preparation method, and interface optimization measures employed. The review also highlights the existing challenges associated with MOF materials in SSBs applications and proposes potential solutions and future development prospects to guide the advancement of MOFs-based SSEs. By providing a comprehensive assessment of the applications of MOFs in LMSSBs, this review aims to offer valuable insights and guidance for the development of MOF-based SSEs, addressing the key issues faced by these materials in SSBs technology.