Abstract Highly-ordered TiO2 nanotube arrays (TNTs) were successfully synthesized on a Ti foil using a cost-effective two-step electrochemical anodization, into which NiO nanoparticles (NPs) were decorated uniformly using ultrasound-assisted deposition, forming NiO/TNTs p-n junctions. These nanostructures were characterized by X-ray Diffraction, Field Emission Scanning Electron Microscope, Energy Dispersive X-ray Spectroscopy, and Photoluminescence spectra. The photocatalytic activity of pure TNTs and NiO/TNTs samples was evaluated through the photodegradation of RB dye as a pollutant model under sunlight irradiation. Results demonstrated that the photodegradation efficiency of pure TNTs and NiO/TNTs samples were 77% and 97.1%, respectively. NiO/TNTs p-n junction showed higher photodegradation efficiency in comparison to pure TNTs; and this improvement may be attributed to the influence of NiO NPs that can enhance separation of charge carriers. The mechanisms of formation of NiO/TNTs p-n junctions and the influence of NiO NPs on their photocatalytic activity were also discussed.

中文翻译：

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NiO/TNTs pn结的合成在阳光照射下具有高光催化活性

摘要 使用具有成本效益的两步电化学阳极氧化在钛箔上成功合成了高度有序的 TiO2 纳米管阵列 (TNTs)，其中使用超声辅助沉积均匀装饰 NiO 纳米颗粒 (NPs)，形成 NiO/TNTs pn 结. 这些纳米结构的特征在于 X 射线衍射、场发射扫描电子显微镜、能量色散 X 射线光谱和光致发光光谱。通过在阳光照射下作为污染物模型的 RB 染料的光降解来评估纯 TNT 和 NiO/TNT 样品的光催化活性。结果表明，纯 TNTs 和 NiO/TNTs 样品的光降解效率分别为 77% 和 97.1%。与纯 TNTs 相比，NiO/TNTs pn 结显示出更高的光降解效率；这种改进可能归因于可以增强电荷载流子分离的 NiO NPs 的影响。还讨论了 NiO/TNTs pn 结的形成机制和 NiO NPs 对其光催化活性的影响。