Initiation and Progression of Anisotropic Galvanic Replacement Reactions in a Single Ag Nanowire: Implications for Nanostructure Synthesis

Silvia Canepa, Murat Nulati Yesibolati, Jakob Schiøtz, Shima Kadkhodazadeh, Wei Huang, Hongyu Sun*, Kristian Mølhave*

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

Abstract

The galvanic replacement reaction(GRR) is a convenient method for synthesizing hollow/porous noble metal nanostructures with energy,health, and environmental applications. Understanding the reaction mechanism is important for optimizing the produced nanostructures’physicochemical properties. Using liquid-phase scanning transmission electron microscopy (LPSTEM), we quantitatively analyzed the GRR processin individual silver nanowires (AgNWs) reacting with an aqueous HAuCl4 solution. The experiments and atomic-scale simulations show that GRR is a highly selective process with respect to the exposed surface facets, and we discover that the process progression is influenced by the internal crystal domains. We observe that the etching of AgNWs starts preferentially from facets with high energy sites while not favorable on low energy {111} facets, where even the internal twin facets within the nanostructures are found to be temporarily stable. The LPSTEM-observed etch rates in single or multiple crystal segmentsin AgNWs are shown to approach diffusion-limited conditions. These results provide intricate and detailed insights into the GRR process, which are difficult to achieve by other methods, and such studies will be beneficial for the understanding of how the surface energy and number of available surface sites influence the initiation probability, which will theoretically guide the synthesis of nanostructures, also supported with the deeper understanding of how the internal structure may influence the process.
Original languageEnglish
JournalACS Applied Nano Materials
Volume4
Issue number11
Pages (from-to)12346–12355
ISSN2574-0970
DOIs
Publication statusPublished - 2021

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