Nano-Gold Diggers: Au-Assisted SiO2-Decomposition and Desorption in Supported 
Nanocatalysts

Ono, Luis K.; Behafarid, Farzad; Roldan Cuenya, Beatriz

doi:10.1021/nn404744b

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Nano-Gold Diggers: Au-Assisted SiO₂-Decomposition and Desorption in Supported Nanocatalysts

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Ono, L. K., Behafarid, F., & Roldan Cuenya, B. (2013). Nano-Gold Diggers: Au-Assisted SiO₂-Decomposition and Desorption in Supported Nanocatalysts. ACS Applied Nano Materials, 7(11), 10327-10334. doi:10.1021/nn404744b.

Cite as: https://hdl.handle.net/21.11116/0000-0006-CD0A-9

Abstract

An investigation of the thermal stability of size-selected Au nanoparticles (NPs) synthesized via inverse micelle encapsulation and deposited on SiO₂(4 nm)/Si(100) is presented. The size and mobility of individual Au NPs after annealing at elevated temperatures in ultrahigh vacuum (UHV) was monitored via atomic force microscopy (AFM). An enhanced thermal stability against coarsening and lack of NP mobility was observed up to 1343 K. In addition, a drastic decrease in the average NP height was detected with increasing annealing temperature, which was not accompanied by the sublimation of Au atoms/clusters in UHV. The apparent decrease in the Au NP height observed is assigned to their ability to dig vertical channels in the underlying SiO₂ support. More specifically, a progressive reduction in the thickness of the SiO₂ support underneath and in the immediate vicinity of the NPs was evidenced, leading to NPs partially sinking into the SiO₂ substrate. The complete removal of silicon oxide in small patches was observed to take place around the Au NPs after annealing at 1343 K in UHV. These results reveal a Au-assisted oxygen desorption from the support via reverse oxygen spillover to the NPs.