2024-11-04 バッファロー大学(UB)
＜関連情報＞
- https://www.buffalo.edu/news/releases/2024/11/flame-aerosol-nanoparticles-studies.html
- https://www.sciencedirect.com/science/article/abs/pii/S2590238524004296
- https://www.nature.com/articles/s41467-024-53678-4
高エントロピー・ナノセラミックスへの一般的な火炎エアロゾル経路 A general flame aerosol route to high-entropy nanoceramics
Shuo Liu, Chih-Wen Pao, Jeng-Lung Chen, Sichi Li, Kaiwen Chen, Zhengxi Xuan, Chengyu Song, Jeffrey J. Urban, Mark T. Swihart, Chaochao Dun
Matter Available online: 27 August 2024
DOI:https://doi.org/10.1016/j.matt.2024.07.019
Graphical abstract
Highlights
- A general flame aerosol process to fabricate diverse high-entropy nanoceramics
- Thermal stability enhanced by sluggish kinetics and grain refinement
- Entropically driven dispersion of single-atom active sites
- High-entropy catalyst achieves superior performance for H2 reduction of CO2
Progress and potential
High-entropy ceramic oxides feature five or more cations randomly distributed among identical sites in a single crystal phase. They have shown great promise in energy-related applications, such as catalysis, energy storage, and thermal management, by vastly expanding the space of accessible material compositions and resulting properties. However, current synthesis methods are energy intensive, costly, and limited to thermodynamically stable structures. This article describes a versatile and scalable flame aerosol method that can produce both stable and metastable high-entropy materials with diverse crystal structures, including a record-breaking 22-cation-element fluorite phase. The laboratory-scale method reported here has a clear path to industrial-scale implementation and thus toward establishing high-entropy oxides as commercially viable materials. Investment in scale-up for a specific application will be essential to broader impact.
Summary
High-entropy ceramics are an emerging class of materials with fascinating characteristics. However, elemental immiscibility and crystal complexity limit the development of a general synthesis strategy, and common methods yield bulk materials. Here, we introduce a transformative non-equilibrium flame aerosol technique for synthesizing high-entropy nanoceramics. This scalable, one-step process enables the production of high-entropy oxide nanoceramics with an unprecedented diversity of crystal structures, including fluorite-phase materials that integrate up to 22 distinct cation elements. The method’s capacity for entropic stabilization and grain refinement significantly improves the thermal stability of these nanostructures. In a representative application, a Pt-(MgCoNiCuZn)O high-entropy single-atom catalyst showed superior activity and long-term stability, maintaining constant CO2 conversion over 670 h and dramatically outperforming conventional catalysts. The general approach opens a vast composition and structure space for the creation of high-entropy oxide nanomaterials for application across diverse fields, including catalysis, energy storage, sensing, and thermal management.
運動学的に安定化した有機金属骨格への一般的な火炎エアロゾル経路 A general flame aerosol route to kinetically stabilized metal-organic frameworks
Shuo Liu,Chaochao Dun,Feipeng Yang,Kang-Lan Tung,Dominik Wierzbicki,Sanjit Ghose,Kaiwen Chen,Linfeng Chen,Richard Ciora,Mohd A. Khan,Zhengxi Xuan,Miao Yu,Jeffrey J. Urban & Mark T. Swihart
Nature Communications Published:30 October 2024
DOI:https://doi.org/10.1038/s41467-024-53678-4
Abstract
Metal-organic frameworks (MOFs) are highly attractive porous materials with applications spanning the fields of chemistry, physics, biology, and engineering. Their exceptional porosity and structural flexibility have led to widespread use in catalysis, separation, biomedicine, and electrochemistry. Currently, most MOFs are synthesized under equilibrium liquid-phase reaction conditions. Here we show a general and versatile non-equilibrium flame aerosol synthesis of MOFs, in which rapid kinetics of MOF formation yields two distinct classes of MOFs, nano-crystalline MOFs and amorphous MOFs. A key advantage of this far-from-equilibrium synthesis is integration of different metal cations within a single MOF phase, even when this is thermodynamically unfavorable. This can, for example, produce single-atom catalysts and bimetallic MOFs of arbitrary metal pairs. Moreover, we demonstrate that dopant metals (e.g., Pt, Pd) can be exsolved from the MOF framework by reduction, forming nanoclusters anchored on the MOF. A prototypical example of such a material exhibited outstanding performance as a CO oxidation catalyst. This general synthesis route opens new opportunities in MOF design and applications across diverse fields and is inherently scalable for continuous production at industrial scales.
