Cerium doped ZnO nanostructured photocatalyst for the degradation of multiple dyes

The development of cost-effective water-treatment methods to remove toxic industrial contaminants is of burgeoning demand today. This paper discusses the superior performance of Ce doped ZnO for the photocatalytic degradation of toxic cationic and anionic dyes. The excellent degradation ability of this easily manoeuvrable solid photocatalyst developed by the facile and low-cost electrochemical method, for the simultaneous removal of multiple dyes, avoiding the need for any post treatments is successfully demonstrated with the synthetic dyes methylene blue, methyl orange, congo red and their mixture. The pH dependence of the photocatalytic efficiency is correlated with its zeta potential. The improved photocatalytic efficiency is attributed to the Ce⁴⁺↔Ce³⁺ redox couple acting as trap centers enhancing the production of superoxide radicals and the reduction of carrier recombination. The scavenger and cyclic stability tests confirm respectively the dominant role of superoxide radicals in photocatalysis and the reusability of the photocatalyst. The photocatalyst is characterized in detail by X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, Rutherford backscattering, high-resolution transmission electron microscopy, selected area electron diffraction, surface charge analysis and diffuse reflectance spectroscopy. The study highlights the prospect of Ce doped ZnO nanostructured film as a high-performing photocatalyst for water treatment.