Synthesis, Structural Characterization, and Sunlight-Induced Photocatalytic Performance of Fe ₂ O ₃ @CuO Core-Shell Nanocatalyst for Methylene Blue

Introduction: The discharge of colored industrial wastewater—especially organic thiazine dyes, which are toxic, mutagenic, and carcinogenic—poses serious environmental and health problems. Methylene blue, a common dye, is toxic and non-biodegradable, and thus requires effective removal methods. Methods: This study designed and evaluated a photocatalytic degradation system based on Fe2 O3 @CuO nanoparticles for methylene blue removal. The nanoparticles were synthesized via chemical precipitation and characterized using FT-IR, XRD, FESEM, TEM, EDS, and DLS. Their photocatalytic performance was evaluated under sunlight irradiation in a batch system, investigating the effects of catalyst dosage, H2 O2 concentration, and solution pH. Dye concentration was measured using a UV-Vis spectrophotometer. Results: Characterization confirmed the formation of nanoparticles with irregular geometric shapes and uniform distribution. The highest degradation efficiency (99.6%) was achieved within 45 minutes at a pH of 9, a catalyst dosage of 150 mg/L, and 6% H2 O2 . The lowest destruction efficiency (15.3%) occurred in the absence of hydrogen peroxide. Efficiency increased with higher H2 O2 and catalyst doses due to increased radical generation. The nanocatalyst showed excellent reproducibility, retaining 97.1% of its initial efficiency after five cycles with no structural changes. Conclusion: Fe2 O3 @CuO nanoparticles demonstrated high efficiency in the photocatalytic degradation of methylene blue under sunlight. The use of non-toxic, readily available materials, excellent reusability, and a free light source makes this process an economically viable and practical method for treating dye-containing effluents.