(231b) Microfluidic Synthesis of Electro-Catalytically Active Nanoparticles

Metallic nanoparticles, owing to their
exceptional properties have gained a lot of research interest. Potential
applications of these nanoparticles are well known in catalysis, pigments,
electronic and magnetic materials, and drug delivery. Recent advances in
colloidal synthesis methods[1]
have enabled us to synthesize nanoparticles of various shapes and sizes. However
the conventional batch processes give a broad size distribution because of poor
mixing and temperature fluctuations. Consequently, they require further size
classification step to obtain uniform particles. In our laboratory these
materials are being synthesized by using microfluidic reactors which offer
rapid mixing and heat transfer effects resulting in precise size control.
Development of high pressure and high temperature micro-reactor techniques[2] has provided
us with unique capability of synthesizing metallic/bimetallic nanoparticles in
a fast, continuous fashion with enhanced homogeneity and monodispersity along
with enabling special synthesis conditions such as segmented gas liquid flow[3].

In this work, we demonstrate the use of microfluidics
for the continuous synthesis of Pt nanodendrites (Pt-ND) and the effect of
synthesis parameters on the electrocatalytic activity of the Pt-ND. Our results
indicate that the synthesized Pt-ND are much more active as compared to
Pt-black obtained from Sigma Aldrich, as indicated in by the cyclic voltammetry
curve (Fig 1 (a), potential wrt standard Ag/AgCl electrode) even though the
amount of Pt-ND loading used is approximately one tenth of Pt-black. We
attribute the effect to dendritic structure (Fig 1 (b)) giving high surface
area of the active sites for the reaction. We discuss the detailed synthesis
method, electrocatalytic and TEM characterizations in order to understand the
effect of synthesis parameters on the electrocatalytic activity of Pt-ND.

Figure 1: (a)
Electrocatalytic activity of synthesized Pt-ND wrt to Pt-black, (b) HRTEM of
Pt-ND