Photocatalytic Degradation of Organic Dyes Using CeO₂–ZnO Nanocomposites Synthesized by Hydrothermal Method

Abstract

Water pollution caused by organic dyes from textile industries poses severe environmental challenges. In this work, CeO₂–ZnO nanocomposites were synthesized via hydrothermal methods and evaluated for photocatalytic degradation of methylene blue under UV–Vis irradiation. X-ray diffraction analysis confirmed the coexistence of cubic CeO₂ and hexagonal ZnO phases, while scanning electron microscopy showed spherical nanoparticles with sizes ranging between 25–40 nm. UV–Vis diffuse reflectance spectroscopy revealed band gap narrowing from 3.2 eV (ZnO) to 2.8 eV in CeO₂–ZnO composites, enhancing visible light activity. Photocatalytic degradation efficiency reached 92% within 120 minutes, significantly higher than pure ZnO (65%). The improved performance was attributed to heterojunction formation, which facilitated charge carrier separation and suppressed recombination. Kinetic studies indicated pseudo-first-order reaction behavior, and reusability tests confirmed sustained activity after four cycles. The findings suggest CeO₂–ZnO nanocomposites as cost-effective, efficient photocatalysts for wastewater treatment applications.