Song Yinghao, Ling Li, Westerhoff Paul, Shang Chii
Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Hong Kong, China.
School of Sustainable Engineering and the Built Environment and Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment (NEWT), Arizona State University, Tempe, AZ, USA.
Nat Commun. 2021 Jul 2;12(1):4101. doi: 10.1038/s41467-021-24370-8.
Coupling photocatalyst-coated optical fibers (P-OFs) with LEDs shows potential in environmental applications. Here we report a strategy to maximize P-OF light usage and quantify interactions between two forms of light energy (refracted light and evanescent waves) and surface-coated photocatalysts. Different TiO-coated quartz optical fibers (TiO-QOFs) are synthesized and characterized. An energy balance model is then developed by correlating different nano-size TiO coating structures with light propagation modes in TiO-QOFs. By reducing TiO patchiness on optical fibers to 0.034 cm/cm and increasing the average interspace distance between fiber surfaces and TiO coating layers to 114.3 nm, refraction is largely reduced when light is launched into TiO-QOFs, and 91% of light propagated on the fiber surface is evanescent waves. 24% of the generated evanescent waves are not absorbed by nano-TiO and returned to optical fibers, thus increasing the quantum yield during degradation of a refractory pollutant (carbamazepine) in water by 32%. Our model also predicts that extending the TiO-QOF length could fully use the returned light to double the carbamazepine degradation and quantum yield. Therefore, maximizing evanescent waves to activate photocatalysts by controlling photocatalyst coating structures emerges as an effective strategy to improve light usage in photocatalysis.
将光催化剂包覆的光纤（P-OF）与发光二极管耦合在环境应用中显示出潜力。在此，我们报告一种策略，以最大限度地提高P-OF的光利用效率，并量化两种光能形式（折射光和倏逝波）与表面包覆的光催化剂之间的相互作用。合成并表征了不同的TiO包覆石英光纤（TiO-QOF）。然后通过将不同纳米尺寸的TiO涂层结构与TiO-QOF中的光传播模式相关联，建立了一个能量平衡模型。通过将光纤上TiO的不均匀性降低到0.034 cm/cm，并将光纤表面与TiO涂层之间的平均间距增加到114.3 nm，当光入射到TiO-QOF中时，折射大大降低，并且在光纤表面传播的光中有91%是倏逝波。所产生的倏逝波中有24%未被纳米TiO吸收并返回光纤，从而使水中难降解污染物（卡马西平）降解过程中的量子产率提高了32%。我们的模型还预测，延长TiO-QOF的长度可以充分利用返回的光，使卡马西平的降解和量子产率提高一倍。因此，通过控制光催化剂涂层结构使倏逝波最大化以激活光催化剂，成为提高光催化中光利用效率的有效策略。
