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Taking a different road: following Ag25 and Au25 cluster activation via in situ differential pair distribution
Kazeem O Sulaiman1, Muhammad Zubair2, Graham King3
1Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan S7N 5C9, Canada. robert.scott@usask.ca.
Physical Chemistry Chemical Physics : PCCP
|October 5, 2022
Summary
Differential pair distribution function (dPDF) analysis reveals distinct thermal activation behaviors for gold (Au) and silver (Ag) atom-precise clusters on alumina supports. Au clusters grow, while Ag clusters initially grow then degrade, necessitating tailored activation protocols.
Area of Science:
- Materials Science
- Nanotechnology
- Physical Chemistry
Background:
- Atom-precise metal clusters are crucial nanomaterials with unique properties.
- Understanding their structural evolution under thermal stress is key for applications.
- Complementary characterization techniques are needed for comprehensive structural analysis.
Purpose of the Study:
- To investigate the thermal activation behavior of gold (Au) and silver (Ag) atom-precise clusters on alumina supports.
- To compare the structural changes of Au25(SR)18- and Ag25(SR)18- clusters during thermal activation using in situ differential pair distribution function (dPDF) analysis.
- To establish distinct activation protocols for different metal cluster systems.
Main Methods:
- Synchrotron X-ray total scattering measurements.
- In situ differential pair distribution function (dPDF) analysis.
- Transmission electron microscopy (TEM) for particle size determination.
Main Results:
- Differential PDF (dPDF) analysis provides high-temperature, non-element specific structural information with excellent temporal resolution, complementing EXAFS and TEM.
- Au25(SR)18- clusters on alumina exhibit continuous particle growth via coalescence upon thermal activation, reaching 11.2 ± 2.1 nm at 650 °C.
- Ag25(SR)18- clusters show initial growth to 3.2 ± 0.4 nm at 450 °C, followed by thermal degradation to smaller clusters (1.4 ± 0.2 nm at 650 °C).
Conclusions:
- Atom-precise Au and Ag clusters display significantly different structural responses to thermal activation on alumina supports.
- The observed differences highlight the need for developing distinct, metal-specific thermal activation protocols.
- In situ dPDF is a powerful tool for studying dynamic structural changes in nanomaterials at elevated temperatures.
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