Single pulse deposition of Pd–Ag alloy nanowires on highly oriented pyrolytic graphite: A mechanistic assessment

Single pulse electrodeposition, which differs from the method of multi-pulse electrodeposition, is a process of fabricating nanowires by synchronous nucleation and growth. This report discusses the mechanistic aspect of the effect of overpotentials on the formation of Pd–Ag alloy nanowires on Highly Oriented Pyrolytic Graphite (HOPG) in the process of single pulse electrodeposition. The experiment results show that the deposition of Pd–Ag alloy nanowires at the overpotential of 100–150 mV can be described as an instantaneous nucleation mechanism on active sites of HOPG and a diffusion-controlled 3-D growth. However, when the overpotentials are below 100 mV or over 150 mV, the diffusion-controlled growth is not obeyed in the process of electrodeposition of Pd–Ag alloy. The Pd–Ag alloy nanowires with diameters ranging from 60 to 150 nm and lengths up to 300 μm have been obtained on HOPG by single pulse electrodeposition at the overpotential of 120–150 mV. The alloy nanowire arrays thus deposited are continuous, parallel, and ordered. The Ag content of the alloy nanowires is found to be in the range of 16–25%. These results are discussed to assess some of the mechanistic aspects of the electrodeposition process.