Anti-Galvanic Reduction of Silver Ion on Gold and Its Role in Anisotropic
Growth of Gold Nanomaterials
- Publication date
- Publisher
Abstract
The role of silver ions in the seed-mediated
growth of gold nanostructures has been investigated. Silver submonolayer
or monolayer on specific facet of gold is assumed in previously suggested
mechanism owing to underpotential deposition (UPD) of silver by ascorbic
acid having weak reducing power. Silver overpotential deposition by
ascorbic acid, however, is confirmed by electrochemical stripping
voltammetry, whereas submonolayer of silver on gold is spontaneously
formed by anti-galvanic reduction in the absence of ascorbic acid.
In the presence of cetyltrimethylammonium bromide (CTAB),
silver overpotential deposition by ascorbic acid does not occur, but
submonolayer of silver is formed on gold surface. Adsorption of silver
and CTAB on gold dramatically hindered the electron transfer by the
oxidation of ascorbic acid on gold, which reduces gold ions to metallic
gold in seed-mediated growth. These results provide the evidence to
the in-depth observation of mechanism in seed-mediated growth where
the blocking effect of CTAB/Ag(submonolayer)/Au for oxidation of reducing
agent determine the shape and facet of gold nanomaterials