Advanced Powder Materials最新文献

Water electrolysis via alkaline hydrogen evolution reaction (HER) is a promising approach for large-scale production of high-purity hydrogen at a low cost, utilizing renewable and clean energy. However, the sluggish kinetics derived from the high energy barrier of water dissociation impedes seriously its practical application. Herein, a series of hybrid Pt nanoclusters/Ru nanowires (Pt/Ru NWs) catalysts are demonstrated to accelerate alkaline HER. And the optimized Pt/Ru NWs (10 ​% wt Pt) exhibits exceptional performance with an ultralow overpotential (24 ​mV at 10 ​mA ​cm⁻²), a small Tafel slope (26.3 ​mV dec⁻¹), and long-term stability, outperforming the benchmark commercial Pt/C-JM-20 ​% wt catalyst. This amazing performance also occurred in the alkaline anion-exchange membrane water electrolysis devices, where it delivered a cell voltage of about 1.9 ​V at 1 ​A ​cm⁻² and an outstanding stability (more than 100 ​h). The calculations have revealed such a superior performance exhibited by Pt/Ru NWs stems from the formed heterointerfaces, which significantly reduce the energy barrier of the decisive rate step of water dissociation via cooperative-action between Pt cluster and Ru substance. This work provides valuable perspectives for designing advanced materials toward alkaline HER and beyond.

The Janus MoSSe and alloy MoS_xSe_(1-x), belonging to the family of two-dimensional (2D) transition metal dichalcogenides (TMDs), have gained significant attention for their potential applications in nanotechnology. The unique asymmetric structure of Janus MoSSe provides intriguing possibilities for tailored applications. The alloy MoS_xSe_(1-x) offers a tunable composition, allowing for the fine-tuning of the properties to meet specific requirements. These materials exhibit remarkable mechanical, electrical, and optical properties, including a tunable band gap, high absorption coefficient, and photoconductivity. The vibrational and magnetic properties also make it a promising candidate for nanoscale sensing and magnetic storage applications. Properties of these materials can be precisely controlled through different approaches such as size-dependent properties, phase engineering, doping, alloying, defect and vacancy engineering, intercalation, morphology, and heterojunction or hybridisation. Various synthesis methods for 2D Janus MoSSe and alloy MoS_xSe_(1-x) are discussed, including hydro/solvothermal, chemical vapour transport, chemical vapour deposition, physical vapour depositio, and other approaches. The review also presents the latest advancements in Janus and alloy MoSSe-based applications, such as chemical and gas sensors, surface-enhanced Raman spectroscopy, field emission, and energy storage. Moreover, the review highlights the challenges and future directions in the research of these materials, including the need for improved synthesis methods, understanding of their stability, and exploration of new applications. Despite the early stages of research, both the MoSSe-based materials have shown significant potential in various fields, and this review provides valuable insights for researchers and engineers interested in exploring its potential.

High-energy density dielectrics for electrostatic capacitors are in urgent demand for advanced electronics and electrical power systems. Poly(vinylidene fluoride) (PVDF) based nanocomposites have attracted remarkable attention by intrinsic high polarization, flexibility, low density, and outstanding processability. However, it is still challenging to achieve significant improvement in energy density due to the common contradictions between electric polarization and breakdown strength. Here, we proposed a novel facile strategy that simultaneously achieves the construction of in-plane oriented BaTiO₃ nanowires and crystallization modulation of PVDF matrix via an in-situ uniaxial stretch process. The polar phase transition and enhanced Young's modulus facilitate the synergetic improvement of electric polarization and voltage endurance capability for PVDF matrix. Additionally, the aligned distribution of nanowires could reduce the contact probability of nanowire tips, thus alleviating electric field concentration and hindering the conductive path. Finally, a record high energy density of 38.3 ​J/cm³ and 40.9 ​J/cm³ are achieved for single layer and optimized sandwich-structured nanocomposite, respectively. This work provides a unique structural design and universal method for dielectric nanocomposites with ultrahigh energy density, which presents a promising prospect of practical application for modern energy storage systems.

Composition design of high-entropy carbides is a topic of great scientific interest for the hot-end parts in the aerospace field. A novel theoretical method through an inverse composition design route, i.e. initially ensuring the oxide scale with excellent anti-ablation stability, is proposed to improve the ablation resistance of the high-entropy carbide coatings. In this work, the (Hf_0.36Zr_0.24Ti_0.1Sc_0.1Y_0.1La_0.1)C_1-δ (HEC) coatings were prepared by the inverse design concept and verified by the ablation resistance experiment. The linear ablation rate of the HEC coatings is −1.45 ​μm/s, only 4.78 % of the pristine HfC coatings after the oxyacetylene ablation at 4.18 ​MW/m². The HEC possesses higher toughness with a higher Pugh's ratio of 1.55 in comparison with HfC (1.30). The in-situ formed dense (Hf_0.36Zr_0.24Ti_0.1Sc_0.1Y_0.1La_0.1)O_2-δ oxide scale during ablation benefits to improve the anti-ablation performance attributed to its high structural adaptability with a lattice constant change not exceeding 0.19 % at 2000–2300 ​°C. The current investigation demonstrates the effectiveness of the inverse theoretical design, providing a novel optimization approach for ablation protection of high-entropy carbide coatings.

Proton exchange membrane water electrolysis (PEMWE) plays a critical role in practical hydrogen production. Except for the electrode activities, the widespread deployment of PEMWE is severely obstructed by the poor electron-proton permeability across the catalyst layer (CL) and the inefficient transport structure. In this work, the PEDOT:F (Poly(3,4-ethylenedioxythiophene):perfluorosulfonic acid) ionomers with mixed proton-electron conductor (MPEC) were fabricated, which allows for a homogeneous anodic CL structure and the construction of a highly efficient triple-phase interface. The PEDOT:F exhibits strong perfluorosulfonic acid (PFSA) side chain extensibility, enabling the formation of large hydrophilic ion clusters that form proton-electron transport channels within the CL networks, thus contributing to the surface reactant water adsorption. The PEMWE device employing membrane electrode assembly (MEA) prepared by PEDOT:F-2 demonstrates a competitive voltage of 1.713 ​V under a water-splitting current of 2 ​A ​cm⁻² (1.746 ​V at 2A cm⁻² for MEA prepared by Nafion D520), along with exceptional long-term stability. Meanwhile, the MEA prepared by PEDOT:F-2 also exhibits lower ohmic resistance, which is reduced by 23.4 ​% and 17.6 ​% at 0.1 ​A ​cm⁻² and 1.5 ​A ​cm⁻², respectively, as compared to the MEA prepared by D520. The augmentation can be ascribed to the superior proton and electron conductivity inherent in PEDOT:F, coupled with its remarkable structural stability. This characteristic enables expeditious mass transfer during electrolytic reactions, thereby enhancing the performance of PEMWE devices.

Solar-driven water splitting for photocatalytic hydrogen evolution is considered a highly promising and cost-effective solution to achieve a stable renewable energy supply. However, the sluggish kinetics of electron-hole pairs’ separation poses challenges in attaining satisfactory hydrogen production efficiency. Herein, we synthesized the exceptional performance of highly crystalline C₃N₅ (HC–C₃N₅) nanosheet as a photocatalyst, demonstrating a remarkable hydrogen evolution rate of 3.01 ​mmol ​h⁻¹ ​g⁻¹, which surpasses that of bulk C₃N₅ (B–C₃N₅) by a factor of 3.27. Experimental and theoretical analyses reveal that HC-C₃N₅ nanosheets exhibit intriguing macroscopic photoinduced color changes, effectively broadening the absorption spectrum and significantly enhancing the generation of excitons. Besides, the cyano groups in HC-C₃N₅ efficiently captures and converts photoexcited electrons into bound states, thereby prolonging their lifetimes and effectively separating electrons and holes into catalytically active regions. This research provides valuable insights into the establishment of bound electronic states for developing efficient photocatalysts.

Sunlight-driven photocatalysis, which can produce clean fuels and mitigate environmental pollution, has received extensive research attention due to its potential for addressing both energy shortages and environmental crises. Bismuth (Bi)-based photocatalysts with broad spectrum solar-light absorption and tunable structures, exhibit promising applications in solar-driven photocatalysis. Oxygen vacancy (OV) engineering is a widely recognized strategy that shows great potential for accelerating charge separation and small molecule activation. Based on OV engineering, this review focuses on Bi-based photocatalysts and provides a comprehensive overview including synthetic methods, regulation strategies, and applications in photocatalytic field. The synthetic methods of Bi-based photocatalysts with OVs (BPOVs) are classified into hydrothermal, solvothermal, ultraviolet light reduction, calcination, chemical etching, and mechanical methods based on different reaction types, which provide the possibility for the structural regulation of BPOVs, including dimensional regulation, vacancy creation, elemental doping, and heterojunction fabrication. Furthermore, this review also highlights the photocatalytic applications of BPOVs, including CO₂ reduction, N₂ fixation, H₂ generation, O₂ evolution, pollutant degradation, cancer therapy, and bacteria inactivation. Finally, the conclusion and prospects toward the future development of BPOVs photocatalysts are presented.

To enhance the high-temperature adaptability of copper-based composite materials and C–C/SiC discs, this article innovatively introduces a method of replacing graphite with sepiolite, resulting in the successful fabrication of samples with exceptional mechanical and friction properties. The results reveal that moderate incorporation (less 6%) of sepiolite provides a particle reinforcement effect, resulting in an improvement of mechanical properties. Interestingly, the addition of sepiolite causes a change in the traditional saddle-shaped friction curve due to high temperature lubrication. Meanwhile, the primary advantage of sepiolite lies in its superior abrasion resistance, evident in the increased friction coefficient and altered wear mechanisms with higher sepiolite content. The wear resistance is optimal at 200 ​Km/h (400 ​°C). Particularly, the unique composition of the friction layer (outermost layer: a composite film consisting of B₂O₃, sepiolite, graphite, and metal oxide films; intermediate layer: metal oxide films) plays a pivotal role in improving friction stability. Finally, there are significant optimizations in the GA algorithm, especially GA-GB model has the best prediction effect on the maximum friction temperature.

Additive manufacturing of fiber-reinforced polymer composites has garnered great interest due to its potential in fabricating functional products with lightweight characteristics and unique material properties. However, the major concern in polymer composites remains the presence of pore defects, as a thorough understanding of pore formation is insufficient. In this study, a powder-scale multiphysics framework has been developed to simulate the printing process of fiber-reinforced polymer composites in powder bed fusion additive manufacturing. This numerical framework involves various multiphysics phenomena such as particle flow dynamics of fiber-reinforced polymer composite powder, infrared laser–particle interaction, heat transfer, and multiphase fluid flow dynamics. The melt depths of one-layer glass fiber–reinforced polyamide 12 composite parts fabricated by selective laser sintering are measured to validate modelling predictions. The numerical framework is employed to conduct an in-depth investigation of pore formation mechanisms within printed composites. Our simulation results suggest that an increasing fiber weight fraction would lead to a lower densification rate, larger porosity, and lower pore sphericity in the composites.

Silicon is considered one of the most promising anode materials owing to its high theoretical energy density, however, the volume expansion/contraction during electrochemical lithiation/delithiation cycles leads to instability of the solid electrolyte interphase (SEI), which ultimately results in capacity degradation. Herein, the local stress and deformation evolution status of an SEI layer on an anode particle are investigated through a quantitative electrochemical-mechanical model. The impacts of structural uniformity, mechanical strength, and operating conditions on the stability of the SEI layer are investigated in detail. The simulation results demonstrate that when the silicon particle radius decreases from 800 ​nm to 600 and 400 ​nm, the failure time increases by 29% and 65%, respectively, of the original failure time; When the structural defect depth ratio is reduced from 0.6 to 0.4 and 0.2, the failure time increases by 72% and 132%, respectively; For the discharge rate, the condition at 0.1 C has 34% and 139% longer time to failure than that at 0.2 C and 0.3 C, respectively. This work provides insight into the rational design of stable SEI layers and sheds light on possible methods for constructing silicon-based lithium-ion batteries with longer cycling lives.