Self-Propelled 3D-Printed "Aircraft Carrier" of Light-Powered Smart Micromachines for Large-Volume Nitroaromatic Explosives Removal

Self-propelled micro-/nanomotors are in the forefront of materials research, for applications ranging from environmental remediation to biomedicine. However, due to their limited sizes, they can only navigate within small distances, typically in the order of millimeters, which inevitably hinder their use for large-volume real applications. Here it is shown that a 3D-printed millimeter-scale motor (3DP-motor) can act as "aircraft carrier" of TiO2/Pt Janus micromotors and be used for enhanced large-volume environmental remediation applications. The 3DP-motor can move fast for tens of meters through the Marangoni effect by asymmetrically releasing ethanol. During its navigation, this 3DP-motor can carry and slowly release in solution TiO2/Pt Janus micromotors which can be propelled by light illumination while acting as photodegradation agents. Highly efficient degradation of nitroaromatic explosives over a large solution area is achieved. A wall-following motion of the 3DP-motor without external guidance is also demonstrated which is generated by the chemiosmotic flow at the wall vicinity. This can be easily tuned by changing the wettability of the wall surface and also modifying the shape of 3DP-motor, leading to different motion behaviors. This work introduces a new concept of micromotors carried by large millimeter sized motors to traverse long distances and it should find a broad range of applications.