Understanding the nanowires electrodeposition

Usually the synthesis of nanowires by electrodeposition is controlled by transport (diffusion, convection or migration).Like the deposition in others systems (microelectrodes), the influence of each one on the velocity of the process depend of the bath preparation (support electrolyte, pH, concentration and kind of the species) the configuration of the cell and the electrodeposition method. For example for high ion concentration, without support electrolyte, the migration is the principal factor; with diluted solutions and support electrolyte, the diffusion takes the control. The effect of the convection depend of the configuration of the cell, if the working electrode (polycarbonate track-etched foil) are in the bottom of the cell, the natural convection could be important and if you applied a force convection (agitation or rotating disk) the convection will be the main factor in the deposition control.  

In the next figure I show you a schematic representation of the process including SEM images and the relation ship with the current in a potenciostatic process.

How to make metalic nanowires

the easiest way is by electrodeposition, I have been working with the synthesis of diferent metas. following I show you an example with the nickel deposition:

A 20 µm-thick polycarbonate track-etched foil, with 200 nm diameter pores and pore density of 5.8x10⁸ pore/cm², was used as template for the electrodeposition of nickel nanowires. One side of the polycarbonate membrane was sputtered with gold to provide electrical contact, and a thin film of nickel was electrodeposited from a traditional aqueous Watts solution of 120 g/l NiSO₄, 20 g/l NiCl₂ and 30 g/l H₃BO₄. This was the support for the electrodeposition of the nickel nanowire array, carried out potentiostatically from the Watts solution at -950 mV vs. Ag/AgCl. Finally, after deposition of the nanowires the polycarbonate track-etched foil was dissolved using dichloromethane. Scanning electron microscopy (SEM) was used to characterize the nanostructure of the nickel sensor.

 

plycarbonate track-etched foil, with and without gold (electric contact)

 

SEM images of nickel nanowires