Defect assisted Reactive Oxygen Species generation for photocatalytic degradation of methylene blue by nano-structured zinc oxide synthesized in CTAB medium

Abstract

Herein, we report facile, room temperature synthesis of undoped zinc oxide semiconductor nanoparticles and their efficient photocatalytic property towards methylene blue dye degradation. Synthesis of zinc oxide nanoparticles was carried out by facile, eco-friendly and cost-effective, CTAB-assisted method using various aliphatic amines (methyl amine, dimethyl amine and n-butyl amine) as bases. The phase purity, structure, crystallinity, morphology and optical properties of the materials obtained with different aliphatic amines were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–Vis and photoluminescence spectroscopy investigations. It was proved that the different aliphatic amines used manipulates both photodegradation properties and morphology of the undoped ZnO materials. The nanomaterial synthesized with n-butyl amine showed the highest catalytic degradation due to high absorption (∼40%) in visible region. The presence of oxygen and zinc vacancies were confirmed from the two emission bands under UV excitation in photoluminescence (PL) studies. Visible light-driven photocatalytic activity of the prepared ZnO nanorods was evaluated by measuring the photodegradation of widely used industrial organic pollutants methylene blue, showed good efficiency of the catalytic samples. In this present study, we propose a mechanism involving e-h pair generation through bandgap and ROS generation assisted aptly by the presence of defects, facilitating the photo-catalytic activity towards dye degradation.