Elaboration et caractérisation physico-chimique de nanostructures d'oxyde de Zinc (ZnO) en vue d'applications photoélectrocatalytique

Abstract

Zinc oxide (ZnO) nanostructures have been synthesized by electrochemical deposition. The nanostructures were developed by electrodeposition under direct potential (DE) and pulsed potential (PE) onto Indium-doped tin oxide (ITO) substrate from Zinc nitrate solution (Zn(NO3)2). The results show that the phoelectrochemical properties of ZnO thin films obtained by pulsed electrodeposition are better than those obtained by direct electrodeposition. Thus, we chose the PE method for the elaboration of ZnO thin films and we varied the deposition time (ton) and the rest time (toff). The films obtained were used as electrodes in the photoelectrodegradation of the anionic dyes: methylene blue (MB) and methyl orange (MO). Those latter are used as model molecules of organic pollutants. The physicochemical characterizations show that the properties and the photo-activity of the ZnO films are better at short durations of ton = 1s and toff = 1s. X-ray diffraction analysis revealed that the obtained ZnO is pure and has a hexagonal wurtzite structure with a preferred orientation along the c axis. Scanning electron microscopy (SEM) images present a significant shift towards nanodrodes at short deposition duration. The photocurrent response revealed that the conductivity of ZnO thin films is n-type and that the response is higher at low ton values. The ZnO film deposited during 1s for a rest time toff = 1s allows faster degradation of methylene blue and methyl orange