Mutual interplay of ZnO micro- and nanowires and methylene blue during cyclic photocatalysis process

Abstract

Water purification through photocatalysis is the most important requirement due to the increased health, environmental and energy conservation concerns. Metal oxide nanostructures have played a very prominent role in this direction. ZnO is a promising material in terms of nanostructuring and photocatalysis. This study presents a unique easy-to-follow synthesis for ZnO micro- and nanowires by a flame-based approach. The photocatalytic activity of these grown ZnO nano- and microwires against methylene blue (MB) has been investigated in detail and a possible decomposition pathway is proposed. During repeated photocatalysis, a significant improvement in the decomposition rate was achieved which is mainly attributed to surface modifications of the ZnO wires due to the reaction with MB as confirmed by Raman-spectroscopy and X-ray photoelectron spectroscopy (XPS) investigations. The impact of the MB over involved nanostructures is thus an important aspect for the efficiency of the photocatalysis which is briefly presented here.