Thermal Activation of Gold Atom Diffusion in Au@Pt Nanorods

A Pedrazo-Tardajos and EA Irmak and V Kumar and A Sanchez-Iglesias and QY Chen and M Wirix and B Freitag and W Albrecht and S Van Aert and LM Liz-Marzan and S Bals, ACS NANO, 16, 9608-9619 (2022).

DOI: 10.1021/acsnano.2c02889

Understanding the thermal stability of bimetallic nanoparticles is of vital importance to preserve their functionalities during their use in a variety of applications. In contrast to well-studied bimetallic systems such as Au@Ag, heat-induced morphological and compositional changes in Au@Pt nanoparticles are insufficiently understood, even though Au@Pt is an important material for catalysis. To investigate the thermal instability of Au@Pt nanorods at temperatures below their bulk melting point, we combined in situ heating with two-and three-dimensional electron microscopy techniques, including three-dimensional energy- dispersive X-ray spectroscopy. The experimental results were used as input for molecular dynamics simulations, to unravel the mechanisms behind the morphological transformation of Au@Pt core-shell nanorods. We conclude that thermal stability is influenced not only by the degree of coverage of Pt on Au but also by structural details of the Pt shell.

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