Bubble-Propelled Hierarchical Porous Micromotors from Evolved Double Emulsions

Bubble-propelled micromotors with well-engineered hierarchical porous structures are developed by a simple and flexible strategy for efficient water decontamination. Controllably and spontaneously evolved double emulsions from microfluidics are used as templates for continuous fabrication of the micromotors in one-step. The micromotors possess interconnected hierarchical porous structures with two well-aligned microscale pores incorporated in nanoporous matrix. The opening hole of one microscale pore at the bottom of micromotor is decorated with Fe3O4@Ag nanoparticles to decompose H2O2 for bubble-propelled motion. Due to their hydrophobic and magnetic hierarchical porous matrix, the micromotors can be used for capture of oil pollutants in water, and then easy recovery by using a magnetic field. Moreover, the micromotors can be flexibly functionalized by simply incorporating functional nanoparticles into the hierarchical porous structures for efficient water decontamination. This is demonstrated by modifying their hierarchical porous structures with thiol-modified SiO2 nanoparticles for efficient removal of heavy metal ions in water. These bubble-propelled hierarchical porous micromotors show great power as tools for efficient decontamination of polluted water. Moreover, the approach based on microfluidic emulsions is promising for continuous and controllable fabrication of novel micromotors with well-engineered structures and advanced functions.