Clean water for human consumption is, in many places, a scarce resource, and efficient schemes to purify water are in great demand. Here, we describe a method to dramatically increase the efficiency of a photocatalytic water purification microreactor. Our hierarchical optofluidic microreactor combines the advantages of a nanostructured photocatalyst with light harvesting by base substrates, together with a herringbone micromixer for the enhanced transport of reactants. The herringbone micromixer further improves the reaction efficiency of the nanostructured photocatalyst by generating counter-rotating vortices along the flow direction. In addition, the use of metal-based substrates underneath the nanostructured catalyst increases the purification capacity by improving the light-harvesting efficiency. The photocatalyst is grown from TiO₂ as a nanohelix film, which exhibits a large surface-to-volume ratio and a reactive microstructure. We show that the hierarchical structuring with micro- to nanoscale features results in a device with markedly increased photocatalytic activity as compared with a solid unstructured catalyst surface. This is evidenced by the successful degradation of persistent aqueous contaminants, sulfamethoxazole, and polystyrene microplastics. The design can potentially be implemented with solar photocatalysts in flow-through water purification systems.

在许多地方，供人类消费的清洁水是一种稀缺资源，而有效的水净化方案需求量很大。在这里，我们描述了一种显着提高光催化水净化微反应器效率的方法。我们的分层光流控微反应器结合了纳米结构光催化剂的优点和基础基板的光收集，以及用于增强反应物传输的人字形微混合器。人字形微混合器通过沿流动方向产生反向旋转的涡流，进一步提高了纳米结构光催化剂的反应效率。此外，在纳米结构催化剂下方使用金属基基材通过提高光捕获效率来提高净化能力。光催化剂由二氧化钛生长₂作为纳米螺旋膜，其表现出大的表面体积比和反应性微结构。我们表明，与固体非结构化催化剂表面相比，具有微米到纳米级特征的分层结构导致器件的光催化活性显着提高。持久性水性污染物、磺胺甲恶唑和聚苯乙烯微塑料的成功降解证明了这一点。该设计可能会在流通式水净化系统中使用太阳能光催化剂来实施。