Electrodeposition of Polypyrrole in TiO2 Nanotube Arrays by Pulsed-Light and Pulsed-Potential Methods

Using highly ordered TiO2 nanotube arrays as the substrate for electropolymerization provides a high surface area for polymer deposit and vertical pathways for electron transport. The challenge is to deposit the polymer on the inner and outer walls of the tubes and to avoid the sealing of the tubes at the mouth. Ideally, this situation could be reached by filling the tubes from the bottom. We demonstrate here that by using pulsed methods (light pulses, potential pulses), the deposition rate can be controlled, leading to a better monomer supply within the nanotubular matrix. The parameters to apply for the deposition are greatly dependent on the nature of the anion in the electrolyte, which determines the rate and the location of the polymer growth at the electrolytic solution/semiconductor interface.