SEM investigations of Fe-doped ZnO powders

Abstract

Zinc oxide (ZnO) is a semiconductor with a wide band gap (Eg=3.37 eV) and numerous applications as photo- catalysts, antibacterial agent, solar cells, gas sensors, etc [1, 2]. However, wide-band gap semiconductors are only activated under ultraviolet (UV) light irradiation, which limits their practical applications. The doping of various transition-metal cations or anions into wide-band gap semiconductors has been extensively studied to increase the visible-light absorption of these photocatalysts. In order to develop ZnO visible-light photocatalyst activity, ZnO was doped with Fe3+ because bulk-doped Fe(III) ions acts as visible-light absorbers. In the present study, we prepared ZnO doped with 0-3 at.% Fe by hydrothermal method, in the absence and/or presence of a surfactant (CTAB) and, we investigated the as-obtained powders by X-ray diffraction, scanning electron microscope (SEM) and the photocatalytic tests on methylene blue (MB) in both UV and visible spectral regions. As results, we found that the morphologic and photocatalytic properties of the two series of samples - iron doped ZnO with and without surfactant are in opposition. The photocatalytic activity in both UV and visible spectral region for the samples prepared without surfactant decreases as the iron content in samples increases while, an increase of the photocatalytic properties can be observed in the case of samples prepared with surfactant as the iron content increases, in agreement with UV-vis reflection measurements. Our results highlight the beneficial role of iron and surfactant on the photocatalytic properties of ZnO [3,4].