Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
Nano Lett., Article ASAP
DOI: 10.1021/nl303576q
Publication Date (Web): December 18, 2012
Copyright © 2012 American Chemical Society
From their realization just over a decade ago, nanopores in silicon
nitride membranes have allowed numerous transport-based single-molecule
measurements. Here we report the use of these nanopores as subzeptoliter
mixing volumes for the controlled synthesis of metal nanoparticles.
Particle synthesis is controlled and monitored through an electric field
applied across the nanopore membrane, which is positioned so as to
separate electrolyte solutions of a metal precursor and a reducing
agent. When the electric field drives reactive ions to the nanopore, a
characteristic drop in the ion current is observed, indicating the
formation of a nanoparticle inside the nanopore. While traditional
chemical synthesis relies on temperature and timing to monitor particle
growth, here we observe it in real time by monitoring electrical
current. We describe the dynamics of gold particle formation in sub-10
nm diameter silicon nitride pores and the effects of salt concentration
and additives on the particle’s shape and size. The current versus time
signal during particle formation in the nanopore is in excellent
agreement with the Richards growth curve, indicating an access-limited
growth mechanism.
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