Abstract The temperature effect on VO2 thin films synthesized by RF sputtering on their morphological, optical, electrical properties and their activity in the photocatalytic degradation of methylene blue and naproxen was studied. Characterization results presented microcrystallinity for VO2 films treated at 50 and 100 °C. Nevertheless, the untreated films and films treated at 200 °C revealed characteristic peaks of monoclinic and tetragonal phases. SEM micrographs with elemental mapping of VO2 films showed granular morphology and a good oxygen dispersion along the film surface, possibly due to a restructuring on the film occasioned by particle coalescence and vanadium oxide island conformation. The electronic transmittance spectra showed the d–d transition characteristic for the square-pyramidal stereochemistry of vanadium (IV) ion, where the optical band interval was high for films treated at 50 °C. Raman spectroscopy results presented an increment in the V = O/V–O ratio as a function of temperature, probably related to superficial vanadium species formation. X-ray spectroscopy results showed the Onon-lattice/Olattice ratio values higher for films treated at 50 °C than the other films, related to an oxide character. The V 2p fit results presented V4+, V5+ regions and satellites for VO2 films thermal treated at 50 °C. The electrical resistivity on the VO2 films decreased as a function of temperature. Finally, the VO2 films thermal treated at 50 °C had higher photocatalytic activity in the degradation of methylene blue and naproxen compared to the other VO2 films, possibly associated with high electron mobility between the surface and the bulk, where the oxygen vacancies act as recombination sites for the e−/h+ pairs during photocatalytic degradation.

中文翻译：

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温度对通过射频溅射沉积的 VO2 薄膜对亚甲蓝和萘普生光催化降解的影响

摘要 研究了温度对射频溅射合成的 VO2 薄膜形态、光学、电学性质及其光催化降解亚甲蓝和萘普生活性的影响。表征结果显示了在 50 和 100 °C 下处理的 VO2 薄膜的微结晶度。然而，未经处理的薄膜和在 200 °C 处理的薄膜显示出单斜相和四方相的特征峰。带有 VO2 薄膜元素映射的 SEM 显微照片显示出颗粒形态和沿薄膜表面良好的氧分散，这可能是由于颗粒聚结和氧化钒岛构象引起的薄膜重组。电子透射光谱显示了钒 (IV) 离子的方形锥体立体化学的 d-d 跃迁特征，其中，在 50 °C 下处理的薄膜的光带间隔很高。拉曼光谱结果显示 V = O/V-O 比率随温度的变化而增加，这可能与表面钒物质的形成有关。X 射线光谱结果显示，在 50 °C 下处理的薄膜的 Onon-lattice/Olattice 比值高于其他薄膜，这与氧化物特性有关。V 2p 拟合结果显示了在 50 °C 下热处理的 VO2 薄膜的 V4+、V5+ 区域和卫星。VO2 膜上的电阻率随温度而降低。最后，与其他 VO2 薄膜相比，在 50°C 下热处理的 VO2 薄膜在降解亚甲蓝和萘普生方面具有更高的光催化活性，这可能与表面和本体之间的高电子迁移率有关，