Advanced Powder Materials最新文献

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.

Nanozymes, a category of nanomaterials endowed with enzyme-mimicking capabilities, have exhibited considerable potential across diverse application domains. This comprehensive review delves into the intricacies of regulating nanozymes through N elements, elucidating the mechanisms governing N element control in the design and application of these nanomaterials. The initial sections introduce the foundational background and significance of nanozymes. Subsequent exploration delves into the detailed discussion of N element regulation mechanisms on nanozymes, encompassing N vacancies, N doping, N coordination, and nitride. These regulatory pathways play an instrumental role in fine-tuning the catalytic activity and specificity of nanozymes. The review further scrutinizes practical applications of N element regulation on nanozymes, spanning sensing detection, infection therapy, tumor therapy, and pollutant degradation. In conclusion, it succinctly summarizes the current research findings and proposes future directions for development. This thorough investigation into the regulation of nanozymes by N elements anticipates precise control over their performance, thereby advancing the extensive utilization of nanozymes in the realms of biomedical and environmental applications.

CO₂ reduction by CH₄ (CRM) to produce fuel is of great significance for solar energy storage and eliminating greenhouse gas. Herein, the catalyst of ultrafine Ni nanoparticles supported on CeZrNiO₂ solid solution (Ni@CZNO) was synthesized by the sol-gel method. High yield of H₂ and CO (58.0 and 69.8 ​mmol ​min⁻¹ ​g⁻¹) and excellent durability (50 ​h) were achieved by photothermal catalytic CRM merely under focused light irradiation. Structural characterization and DFT calculations reveal that CZNO has rich oxygen vacancies that can adsorb and activate CO₂ to produce reactive oxygen species. Oxygen species are transferred to ultrafine Ni nanoparticles through the rich Ni-CZNO interface to accelerate carbon oxidation, thereby maintaining the excellent catalytic stability of the catalyst. Moreover, the experimental results reveal that light irradiation can not only enhance the photothermal catalytic CRM activity through photothermal conversion and molecular activation, but also improve the stability by increasing the concentration of oxygen vacancies and inhibiting CO disproportionation.

Multiphase design is a promising approach to achieve superior ablation resistance of multicomponent ultra-high temperature ceramic, while understanding the ablation mechanism is the foundation. Here, through investigating a three-phase multicomponent ceramic consisting of Hf-rich carbide, Nb-rich carbide, and Zr-rich silicide phases, we report a newly discovered solid-state reaction process among multiphase multicomponent ceramic during ablation. It was found that this solid-state reaction occurred in the matrix/oxide scale interface region. In this process, metal cations are counter-diffused between the multicomponent phases, thereby resulting in their composition evolution, which allows the multicomponent phases to exist stably under a higher oxygen partial pressure, leading to the improvement of thermodynamic stability of three-phase multicomponent ceramic. Additionally, this solid-state reaction process appears synergistic with the preferential oxidation behavior among the oxide scale in enhancing the ablation performance.