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Identification of a Critical Intermediate in Galvanic Exchange Reactions by Single‐Nanoparticle‐Resolved Kinetics
Author(s) -
Smith Jeremy G.,
Yang Qing,
Jain Prashant K.
Publication year - 2014
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201309307
Subject(s) - galvanic cell , materials science , void (composites) , nanoparticle , nanocrystalline material , kinetics , transmission electron microscopy , nanostructure , nanocages , nanoshell , scanning transmission electron microscopy , transition metal , chemical physics , nanotechnology , chemical engineering , chemistry , metallurgy , catalysis , composite material , physics , biochemistry , quantum mechanics , engineering
The realization of common materials transformations in nanocrystalline systems is fostering the development of novel nanostructures and allowing a deep look into the atomistic mechanisms involved. Galvanic corrosion is one such transformation. We studied galvanic replacement within individual metal nanoparticles by using a combination of plasmonic spectroscopy and scanning transmission electron microscopy. Single‐nanoparticle reaction trajectories showed that a Ag nanoparticle exposed to Au 3+ makes an abrupt transition into a nanocage structure. The transition is limited by a critical structural event, which we identified by electron microscopy to comprise the formation of a nanosized void. Trajectories also revealed a surprisingly strong nonlinearity of the reaction kinetics, which we explain by a model involving the critical coalescence of vacancies into a growing void. The critical void size for galvanic exchange to spontaneously proceed was found to be 20 atomic vacancies.