Change of composition and surface plasmon resonance of Pd/Au core/shell nanoparticles triggered by CO adsorption.

Autor:	Ouvrard A; Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Saclay, 91405 Orsay, France., Alyabyeva N; Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Saclay, 91405 Orsay, France., Zakaria AM; Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Saclay, 91405 Orsay, France., Yuan K; Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Saclay, 91405 Orsay, France., Dablemont C; Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Saclay, 91405 Orsay, France., Lazzari R; Institut des NanoSciences de Paris (INSP), CNRS/Sorbonne Université, 75252 Paris, France., Charra F; Service de Physique de l'État Condensé, SPEC, CEA, CNRS, Université Paris-Saclay, CEA/Saclay, F-91191 Gif sur Yvette, France., Bourguignon B; Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Saclay, 91405 Orsay, France.
Jazyk:	angličtina
Zdroj:	The Journal of chemical physics [J Chem Phys] 2024 Sep 28; Vol. 161 (12).
DOI:	10.1063/5.0231175
Abstrakt:	Controlling composition and plasmonic response of bimetallic nanoparticles (NPs) is of great relevance to tune their catalytic activity. Herein, we demonstrate reversible composition and plasmonic response transitions from a core/shell to a bimetallic alloyed palladium/gold NP triggered by CO adsorption and sample temperature. The use of self-organized growth on alumina template film allows scrutinizing the impact of core size and shell thickness onto NP geometry and plasmonic response. Topography, molecular adsorption, and plasmonic response are addressed by scanning tunneling microscopy, vibrational sum frequency generation (SFG) spectroscopy, and surface differential reflectance spectroscopy, respectively. Modeling CO dipolar interaction and optical reflectivity corroborate the experimental findings. We demonstrate that probing CO adsorption sites by SFG is a remarkably sensitive and relevant method to investigate shell composition and follow in real-time Pd atom migration between the core and the shell. Pd-Au alloying is limited to the first two monolayers of the shell and no plasmonic response is found, while for a thicker shell, a plasmonic response is observed, concomitant with a lower Pd concentration in the shell. Above 10-4 mbar, at room temperature, CO adsorption triggers the shell restructuration, forming a Pd-Au alloy that weakens the plasmonic response via Pd migration from the core to the shell. NP annealing at 550 K, after pumping CO, leads to the desorption of remaining CO and gives enough mobility for Pd to migrate back inside the core and recover a pure gold shell with its original plasmonic response. This work demonstrates that surface stoichiometry and plasmonic response can be tuned by using CO adsorption and NP annealing. (© 2024 Author(s). Published under an exclusive license by AIP Publishing.)
Databáze:	MEDLINE
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