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| Main Authors: | , , , , , , , , , |
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| Format: | Preprint |
| Published: |
2026
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2602.00433 |
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| _version_ | 1866918316542525440 |
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| author | McKeown-Green, Amy S. Moradifar, Parivash Zhang, Zisheng Lim, Cedric Barnum, Andrew Yuan, Lin Sinclair, Robert Abild-Pedersen, Frank Ophus, Colin Dionne, Jennifer A. |
| author_facet | McKeown-Green, Amy S. Moradifar, Parivash Zhang, Zisheng Lim, Cedric Barnum, Andrew Yuan, Lin Sinclair, Robert Abild-Pedersen, Frank Ophus, Colin Dionne, Jennifer A. |
| contents | Bimetallic catalysts provide new routes toward sustainable ammonia synthesis, but the structural dynamics controlling their performance under real-world conditions remain poorly understood. Here, we combine in situ gas-cell and multimodal electron microscopy to disentangle the temperature-, pressure-, and chemistry-dependent restructuring of AuRu catalysts, revealing pathways accessible only at atmospheric pressure. As synthesized, AuRu nanocatalysts are polycrystalline face-centered-cubic alloys with Au/Ru intermixing that phase-segregate into Au- and Ru-rich domains with elevated temperature (>450 °C). Increased pressure (~1 atm in 3:1, hydrogen:nitrogen) unlocks pronounced faceting and internal nanovoid formation, which systematic gas-chemistry variation identifies as hydrogen-driven. Density functional theory-based interatomic potentials show that hydrogen can amplify Au/Ru diffusion asymmetry, promoting nanovoid formation via a gas-mediated Kirkendall mechanism. Together, these results bridge the pressure gap between traditional in situ electron microscopy and benchtop ammonia reactors, enabling resolution of distinct restructuring stimuli in multicomponent systems. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2602_00433 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Ammonia Catalyst Evolution Under Reactor Conditions Revealed by Environmental and Multimodal Electron Microscopy McKeown-Green, Amy S. Moradifar, Parivash Zhang, Zisheng Lim, Cedric Barnum, Andrew Yuan, Lin Sinclair, Robert Abild-Pedersen, Frank Ophus, Colin Dionne, Jennifer A. Materials Science Bimetallic catalysts provide new routes toward sustainable ammonia synthesis, but the structural dynamics controlling their performance under real-world conditions remain poorly understood. Here, we combine in situ gas-cell and multimodal electron microscopy to disentangle the temperature-, pressure-, and chemistry-dependent restructuring of AuRu catalysts, revealing pathways accessible only at atmospheric pressure. As synthesized, AuRu nanocatalysts are polycrystalline face-centered-cubic alloys with Au/Ru intermixing that phase-segregate into Au- and Ru-rich domains with elevated temperature (>450 °C). Increased pressure (~1 atm in 3:1, hydrogen:nitrogen) unlocks pronounced faceting and internal nanovoid formation, which systematic gas-chemistry variation identifies as hydrogen-driven. Density functional theory-based interatomic potentials show that hydrogen can amplify Au/Ru diffusion asymmetry, promoting nanovoid formation via a gas-mediated Kirkendall mechanism. Together, these results bridge the pressure gap between traditional in situ electron microscopy and benchtop ammonia reactors, enabling resolution of distinct restructuring stimuli in multicomponent systems. |
| title | Ammonia Catalyst Evolution Under Reactor Conditions Revealed by Environmental and Multimodal Electron Microscopy |
| topic | Materials Science |
| url | https://arxiv.org/abs/2602.00433 |