Super-Assembled Multilayered Mesoporous TiO₂ Nanorockets for Light-Powered Space-Confined Microfluidic Catalysis

In the field of sustainable chemistry, it is still a significant challenge to realize efficient light-powered space-confined catalysis and propulsion due to the limited solar absorption efficiency and the low mass and heat transfer efficiency. Here, novel semiconductor TiO₂ nanorockets with asymmetric, hollow, mesoporous, and double-layer structures are successfully constructed through a facile interfacial superassembly strategy. The high concentration of defects and unique topological features improve light scattering and reduce the distance for charge migration and directed charge separation, resulting in enhanced light harvesting in the confined nanospace and resulting in enhanced catalysis and self-propulsion. The movement velocity of double-layered nanorockets can reach up to 10.5 μm s^-1 under visible light, which is approximately 57 and 119% higher than that of asymmetric single-layered TiO₂ and isotropic hollow TiO₂ nanospheres, respectively. In addition, the double-layered nanorockets improve the degradation rate of the common pollutant methylene blue under sustainable visible light with a 247% rise of first-order rate constant compared to isotropic hollow TiO₂ nanospheres. Furthermore, FEA simulations reveal and confirm the double-layered confined-space enhanced catalysis and self-propulsion mechanism.