Enhanced Piezo-Photocatalytic Degradation of Rhodamine B Using Different ZnO Nanostructures Under Xenon Irradiation and Ultrasonic Activation

Abstract

The contamination of wastewater with synthetic organic dyes has become a significant environmental challenge. To address this issue, zinc oxide (ZnO) has attracted considerable attention due to its non-toxic nature and versatile applications, especially in photocatalytic materials. Enhancing the efficiency of photocatalysis requires reducing electron-hole recombination, which can be achieved through doping or composite formation with other materials. Additionally, the integration of piezoelectric properties presents an effective strategy to enhance ZnO-based photocatalysts, given their excellent piezoelectric characteristics. In this study, the piezo-photocatalysis properties of ZnO nanostructures with spherical, plate-like, and rod-like morphologies were systematically investigated under xenon lamp irradiation coupled with piezo-mechanical stimulation. Rhodamine B (RhB) was employed as a model dye to evaluate photocatalytic performance under various conditions, for example, light irradiation, piezo-assisted activation combined with light irradiation, and the absence of light. The absorbance of the dyes under photocatalytic reaction was then measured using a UV-visible spectrophotometer. The experimental results revealed that the highest dye degradation efficiency was achieved when using rod-like ZnO photocatalyst under combined piezo-assisted and light irradiation. This superior performance can be attributed to its asymmetric geometry, which enhances the generation of an internal electric field on the photocatalyst surface under piezoelectric activation, thereby promoting efficient charge separation. Moreover, the 1D structure of the rod-like facilitates directed electron transport along its longitudinal axis and provides a higher density of active sites, contributing further to their enhanced photocatalytic activity.