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Abstract
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The quest for efficient photocatalysts has positioned ZnO as a material of significant interest, owing to its low cost, non-toxic nature, and general stability. Despite these advantages, its practical application is hampered by several inherent limitations. A wide bandgap (~3.37 eV) confines its light absorption largely to the UV spectrum, while tendencies toward photocorrosion and a rapid recombination of charge carriers further curtail its photocatalytic efficiency. Consequently, strategies to modify ZnO and enhance its optoelectrical properties are actively pursued [1]. To this end, tungsten trioxide (WO3) emerges as a compelling candidate for forming a composite. As an n-type semiconductor with a narrower bandgap (2.5– 2.8 eV), WO3 can absorb a substantial portion of visible light, up to approximately 480 nm. This characteristic, combined with its notable stability, particularly in acidic environments and strong photocurrent response, makes it an ideal partner for augmenting ZnO's performance in solar-driven applications [2]. In our work, a ZnO/WO3 composite was synthesized via a co- precipitation route, with its formation confirmed by FT-IR spectroscopy. We then assessed its efficacy by monitoring the degradation of the methylene blue dye under visible light. The results were striking: using 25 mg of the catalyst at pH 5, the nanocomposite achieved a 94% degradation rate within 90 minutes. This high performance stems from the synergistic partnership between ZnO and WO3. The composite establishes an effective heterojunction structure, which not only broadens the spectrum of utilizable light but also critically suppresses the recombination of photogenerated electrons and holes. Furthermore, the material provides ample active surface areas for the redox reactions to occur. By effectively combining the strengths of both metal oxides, the ZnO/WO3 nanocomposite provides a robust and sustainable platform for addressing persistent industrial pollutants.
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