This paper reports the synthesis of a NiO loaded KNbO₃ nanocomposite via a photodeposition method and its application in photocatalytic N₂ fixation for the first time. Results indicated that the NiO/KNbO₃ composite displayed superior photocatalytic efficiency in NH₃ production under simulated sunlight illumination. The optimal NiO/KNbO₃ sample showed an NH₃-generation rate of 470.6 μmol g⁻¹ h⁻¹, which reaches 4.8 times that of pristine KNbO₃. Various characterization techniques including powder X-ray diffraction (XRD), Raman, X-ray photoelectron spectroscopy (XPS), UV-visible diffuse reflection spectroscopy (DRS), transient photocurrent, electrochemical impedance spectroscopy (EIS), and linear sweep voltammetry (LSV) were applied to reveal the mechanism behind the high photoactivity of NiO/KNbO₃. The addition of NiO nanoparticles showed a slight effect on the specific surface area and the optical properties of KNbO₃, but elevated the charge separation efficiency which was verified to be the key role in affecting the photocatalytic reaction. The introduced NiO fabricated a p–n heterojunction structure with KNbO₃ and hence achieved enhanced efficiency in separating electrons and holes via a type-II mechanism. The cycling test further demonstrated that the NiO/KNbO₃ sample has high photocatalytic stability, indicating its good potential in photocatalytic nitrogen fixation.

中文翻译：

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NiO / KNbO3纳米复合材料的光沉积法制备及其在光催化固氮中的优异性能

本文首次报道了通过光沉积法合成负载NiO的KNbO ₃纳米复合材料及其在光催化N ₂固定中的应用。结果表明，在模拟阳光照射下，NiO / KNbO ₃复合材料在NH _3的生产中显示出优异的光催化效率。最佳NiO / KNbO ₃样品的NH ₃生成速率为470.6μmolg ^-1 h ^-1，是原始KNbO _3的4.8倍。。各种表征技术，包括粉末X射线衍射（XRD），拉曼光谱，X射线光电子能谱（XPS），紫外可见漫反射光谱（DRS），瞬态光电流，电化学阻抗谱（EIS）和线性扫描伏安法（LSV） ）揭示了NiO / KNbO ₃高光活性的机理。NiO纳米粒子的添加对KNbO ₃的比表面积和光学性质影响不大，但提高了电荷分离效率，这被证实是影响光催化反应的关键作用。引入的NiO与KNbO ₃一起制造了ap–n异质结结构，因此提高了电子和空穴的分离效率通过II型机制。循环测试进一步表明，NiO / KNbO ₃样品具有较高的光催化稳定性，表明其在光催化固氮方面的良好潜力。