This paper reports on a Vis-active composite thin film photocatalyst developed by integrating graphitic carbon nitride (g-C₃N₄) as filler in a titanium dioxide (TiO₂) matrix. The thin film deposition procedure follows two steps: (1) the deposition of an intermediate TiO₂ layer on an FTO/glass substrate using spray pyrolysis deposition followed by (2) the deposition of the composite layer (TiO₂–g-C₃N₄) by spraying a diluted sol to get different filler contents (1%_wt–20%_wt) in the composite layer. The deposition was optimised on large substrate dimensions targeting upscaling of the advanced wastewater treatment process. The structural and morphological characterization results were correlated with the photocatalytic activity of the films tested using the methylene blue (MB) standard pollutant under UV + VIS irradiation at low irradiance value, in static regime. The influence of the g-C₃N₄ content on the photodegradation efficiency and stability of the composite layers was observed, with the results indicating 5%_wt of g-C₃N₄ as optimal content. Furthermore, the optimal composite layer was tested in a continuous flow process using MB or imidacloprid (IMD) as pollutant, under simulated solar radiation with a higher irradiance value G_UV+VIS = 800 W/m²; the results show that the photocatalytic efficiency increases with the increase of the radiation intensity. The small variations observed in the transmittance spectra, surface morphology and roughness values before and after the process indicate a good stability of the composites in the aqueous media. Also, successful experiments on large substrates show the potential of TiO₂–g-C₃N₄ two layered thin film photocatalysts for commercial applications for wastewater treatment. This has a great societal impact.

Graphical Abstract

中文翻译：

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用于高级废水处理的大型基底上的 TiO2-g-C3N4 薄膜光催化剂

本文报道了一种通过将石墨氮化碳（gC ₃ N ₄）作为填料集成到二氧化钛（TiO ₂）基质中而开发的可见光活性复合薄膜光催化剂。薄膜沉积过程分为两个步骤：(1) 使用喷雾热解沉积在 FTO/玻璃基板上沉积中间 TiO ₂层，然后 (2) 沉积复合层 (TiO ₂ –gC ₃ N ₄ )通过喷涂稀释的溶胶，在复合层中获得不同的填料含量（1% _wt –20% _{wt ）。}在大尺寸基底上对沉积进行了优化，旨在扩大先进废水处理工艺的规模。结构和形态表征结果与使用亚甲基蓝（MB）标准污染物在低辐照度值的 UV + VIS 照射下静态状态下测试的薄膜的光催化活性相关。_{观察了gC 3} N ₄含量对复合层光降解效率和稳定性的影响，结果表明5％_wt的gC ₃ N ₄为最佳含量。_{此外，使用MB或吡虫啉（IMD）作为污染物，在具有较高辐照度值G UV+VIS}  = 800 W/m ²的模拟太阳辐射下，在连续流动过程中测试了最佳复合层；结果表明，光催化效率随着辐射强度的增加而增加。处理前后观察到的透射光谱、表面形貌和粗糙度值的微小变化表明复合材料在水介质中具有良好的稳定性。_{此外，在大型基底上的成功实验表明了TiO 2} –gC ₃ N ₄两层薄膜光催化剂在废水处理商业应用中的潜力。这具有很大的社会影响。

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