Regular Article

Effects of pulsed electrodeposition parameters on the properties of zinc oxide thin films to improve the photoelectrochemical and photoelectrodegradation efficiency^★

¹ Laboratoire d'électrochimie et matériaux (LEM), Faculté de Technologie. Département de génie des procédés, Université Ferhat Abbas Sétif-1, 19000 Sétif, Algeria
² Laboratoire de LPhia, Université d'Angers, 2 Bd Lavoisier, 49045 Angers, France
³ Laboratoire des Technologies Innovantes (LTI), Université de Jules Verne, IUT de l'Oise, Allée de la Faïencerie, 60100 Creil, France
⁴ Laboratoire de Physique des Interfaces et Couches Minces (LPICM, UMR 7647), Ecole polytechnique, 91128 Palaiseau, France
⁵ Department of Chemistry, Department of Physics, Engineering Physics and Astronomy, Queen's University, Kingston, ON K7L 3N6, Canada

^* e-mail: habelhamesfarid@yahoo.fr

Received: 24 July 2018
Received in final form: 2 December 2018
Accepted: 6 December 2018
Published online: 14 January 2019

Abstract

Zinc oxide (ZnO) thin films were synthesized on ITO glass substrates by electrochemical deposition from a nitrate solution. The deposition potential, bath temperature and annealing temperature were fixed at −1.1 V versus SCE, 80 and 400 °C, respectively. Firstly, we prepared the ZnO thin films by two different electrochemical methods: direct (DE) and pulsed electrodeposition (PE). The results indicate that pulse electrodeposition improves the properties of ZnO thin films compared to direct electrodeposition technique. Secondly, we chose the PE method for the elaboration of ZnO thin films and we varied the time-On (t_on) from 7 to 1 s. Deposited ZnO thin films were characterized using XRD, SEM, optical and photocurrent measurement. X-ray diffraction results indicate that the synthesized ZnO has a pure hexagonal wurtzite structure with a marked preferential orientation along the (002) plane perpendicular to the substrate. SEM analysis reveals that the electrodeposited nanosheets at time-On of 7 s are only hexagonal. A remarkable change in ZnO morphology from nanosheets to nanosheets/nanorods and decrease in gap energy is observed with the decrease in electrodeposition time-On. After optimization in electrodeposition time (t_on), a significant improvement in photocurrent and Methylene Blue (MB) photoelectrocatalytical degradation were observed.