Formation of mesoscopic silver particles at micro- and nano-liquid/liquid interfaces

Silver particles have been deposited at externally polarised 1,2-dichloroethane (DCE)/water interfaces supported at the tip of micro- and nanopipettes. The electrochemical process involved the reduction of silver ion in the aqueous phase by an organic-phase electron donor (butylferrocene). The silver nucleation and growth process was investigated using potential step chronoamperometry, and the resulting current-time transients were analysed to extract nucleus numbers. At larger pipettes, with diameters of several micrometers, multi-particle nucleation was observed and optical microscopy provided direct evidence for metal electrodeposition at the liquid/liquid interface. For pipettes with radii of 0.5 mum or smaller, the current-time behaviour was consistent with single particle generation. Under some conditions, detachment of the particle from the liquid/liquid interface was inferred from the current-time characteristics. and it is suggested that controlled-detachment from micropipettes could provide a method for the deposition of small metal structures on surfaces. (C) 2003 Elsevier B.V. All rights reserved.