Growth of Au on Pt Icosahedral Nanoparticles Revealed by Low-Dose In Situ TEM

A growth mode was revealed by an
in situ TEM study of nucleation and growth of Au on Pt icosahedral
nanoparticles. Quantitative analysis of growth kinetics was carried
out based on real-time TEM data, which shows the process involves:
(1) deposition of Au on corner sites of Pt icosahedral nanoparticles,
(2) diffusion of Au from corners to terraces and edges, and (3) subsequent
layer-by-layer growth of Au on Au surfaces to form Pt@Au core–shell
nanoparticles. The in situ TEM results indicate diffusion of Au from
corner islands to terraces and edges is a kinetically controlled growth,
as evidenced by a measurement of diffusion coefficients for these
growth processes. We demonstrated that in situ electron microscopy
is a valuable tool for quantitative study of nucleation and growth
kinetics and can provide new insight into the design and precise control
of heterogeneous nanostructures.