Pulsed-reverse current electrodeposition of Zn and Zn-TiO2 nanocomposite films

Zn and Zn-TiO2 nanocomposite films were prepared by pulsed-reverse current electrolysis, from acidic zinc sulphate solutions, on a Ti support. The influence of the anodic pulse current, on the electrodeposit structural and morphological characteristics, has been investigated. The samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS). The amount of TiO2 incorporated into the film was determined by induced coupled plasma spectroscopy (ICPS). It was found that the anodic pulse current density (i(a)) plays a remarkable influence on the coatings morphology and zinc crystallite size. When no anodic pulse is applied, both the zinc average crystallite size and TiO2 content present the minimum values. By contrast, the nanocomposites prepared with the highest i(a) value (19 mA cm(-2)), exhibit the highest values for the zinc average crystallite size and TiO2 content. SEM results confirm that the pulse-plating parameters and the presence of boric acid have a strong influence on the deposit surface morphology. Moreover, an increase of the anodic current pulse leads to smoother coating surfaces. XRD, SEM and ICPS data indicate that the increase on the anodic current pulse promotes the incorporation of the nanoparticles into the nanocomposite deposits. (C) 2010 Elsevier B.V. All rights reserved.