Direct observation of the nanoscale Kirkendall effect during galvanic replacement reactions

• DOI: 10.1038/s41467-017-01175-2
• Publication Date: 2017-10-25T20:37:34Z
• Authors: See Wee Chee; Shu Fen Tan; Zhaslan Baraissov; Michel Bosman; Utkur Mirsaidov
• Keywords: Kirkendall Effect; Galvanic cell; Coalescence (physics); Ostwald ripening; Nanorod

Galvanic replacement (GR) is a simple and widely used approach to synthesize hollow nanostructures for applications in catalysis, plasmonics, biomedical research. The reaction driven by the difference electrochemical potential between two metals solution. However, transient stages of this are not fully understood. Here, we show using liquid cell transmission electron microscopy that silver (Ag) nanocubes become via nucleation, growth, coalescence voids inside nanocubes, as they undergo GR with gold (Au) ions at different temperatures. These direct situ observations indicate void formation due nanoscale Kirkendall effect occurs conjunction GR. Although mechanism has been suggested before, it verified experimentally until now. experiments can inform future strategies deriving such providing insights into structural transformations function Au ion concentration, oxidation state Au, temperature.