<i>In Situ</i> High Temperature Synthesis
of Single-Component Metallic Nanoparticles
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Abstract
Nanoparticles (NPs)
dispersed within a conductive host are essential
for a range of applications including electrochemical energy storage,
catalysis, and energetic devices. However, manufacturing high quality
NPs in an efficient manner remains a challenge, especially due to
agglomeration during assembly processes. Here we report a rapid thermal
shock method to <i>in situ</i> synthesize well-dispersed
NPs on a conductive fiber matrix using metal precursor salts. The
temperature of the carbon nanofibers (CNFs) coated with metal salts
was ramped from room temperature to ∼2000 K in 5 ms, which
corresponds to a rate of 400,000 K/s. Metal salts decompose rapidly
at such high temperatures and nucleate into metallic nanoparticles
during the rapid cooling step (cooling rate of ∼100,000 K/s).
The high temperature duration plays a critical role in the size and
distribution of the nanoparticles: the faster the process is, the
smaller the nanoparticles are, and the narrower the size distribution
is. We also demonstrated that the peak temperature of thermal shock
can reach ∼3000 K, much higher than the decomposition temperature
of many salts, which ensures the possibility of synthesizing various
types of nanoparticles. This universal, <i>in situ</i>,
high temperature thermal shock method offers considerable potential
for the bulk synthesis of unagglomerated nanoparticles stabilized
within a matrix