Selective shortening of gold nanorods: when surface functionalization dictates the reactivity of nanostructures

Abdelali Khelfa (1) , Jun Meng (2) , Caroline Byun (1) , Guillaume Wang (1) , Jaysen Nelayah (1) , Christian Ricolleau (1) , Hakim Amara (3) , Hazar Guesmi (2) , Damien Alloyeau (1)

1 MPQ (UMR_7162) - Laboratoire Matériaux et Phénomènes Quantiques
2 ICGM - Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier
3 Laboratoire d'étude des microstructures - LEM, UMR 104, CNRS-ONERA, Université Paris-Saclay

The selective shortening of gold nanorods (NRs) is a directional etching process that has been intensively studied by UV-Vis spectroscopy because of its direct impact on the optical response of these plasmonic nanostructures. Here, liquid-cell transmission electron microscopy is exploited to visualize this peculiar corrosion process at the nanoscale and study the impacts of reaction kinetics on the etching mechanisms. In situ imaging reveals that anisotropic etching requires a chemical environment with a low etching power to make the tips of NRs the only reaction site for the oxidation process. Then, aberration-corrected TEM and atomistic simulations were combined to demonstrate that the disparity between the reactivity of the body and the ends of NRs does not derive from their crystal structure but results from an inhomogeneous surface functionalization. In a general manner, this work highlights the necessity to consider the organic/inorganic natures of nanostructures to understand their chemical reactivity.

Domaines: Science des matériaux [cond-mat.mtrl-sci]; Matière Condensée [cond-mat]

Abdelali Khelfa, Jun Meng, Caroline Byun, Guillaume Wang, Jaysen Nelayah, et al.. Selective shortening of gold nanorods: when surface functionalization dictates the reactivity of nanostructures. Nanoscale, 2020, 12 (44), pp.22658-22667. ⟨10.1039/d0nr06326f⟩. ⟨hal-02998035⟩