Journal
JOURNAL OF PHYSICAL CHEMISTRY C
Volume 121, Issue 9, Pages 5115-5122Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acs.jpcc.6b12847
Keywords
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Funding
- Integrated Mesoscale Architectures for Sustainable Catalysis - IMASC, an Energy Frontier Research Center - U.S. Department of Energy, Office of Science, Basic Energy Sciences [DE-SC0012573]
- National Science Foundation under NSF award [ECS-0335765]
- U.S. Department of Energy by LLNL [DE-AC52-07NA27344]
- Belgian American Educational Foundation (BAEF)
- Wallonie-Bruxelles International (Excellence grant WBI.WORLD)
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3D nanoporous metals made by alloy corrosion have attracted much attention due to various promising applications ranging from catalysis and sensing to energy storage and actuation. In this work we report a new process for the fabrication of 3D open nanoporous metal networks that phenomenologically resembles the nano-Kirkendall hollowing process previously reported for Ag/Au nanowires and nano particles, with the difference that the involved length scales are 10-100 times larger. Specifically, we find that dry oxidation of Ag70Au30 bulk alloy samples by ozone exposure at 150 C-omicron stimulates extremely rapid Ag outward diffusion toward the gas/alloy-surface interface, at rates at least 5 orders of magnitude faster than predicted on the basis of reported Ag bulk diffusion values. The micrometer-thick Ag depleted alloy region thus formed transforms into a 3D open nanoporous network morphology upon further exposure to methanol-O-2 at 150 C-omicron. These findings have important implications for practical applications of alloys, for example as catalysts, by demonstrating that large-scale compositional and morphological changes can be triggered by surface chemical reactions at low temperatures, and that dilute alloys such as Au97Ag3 are more resilient against such changes.
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