Surface Roughening of Pt-Polystyrene Spherical Janus Micromotors for Enhanced Motion Speed

Spherical Janus micromotors (SJMs) have attracted much attention, and their high-speed motion is highly desired due to their various potential applications. However, the conventional template-deposition method often leads to an active Pt coating with a smooth surface, which is unbeneficial to speed enhancement in terms of catalytic reaction. Here, a facile surface roughening method is presented to fabricate the Pt-polystyrene (PS) SJMs with rough Pt surface (or Pt_r-PS SJMs) by plasma-etching the PS colloidal monolayer and then depositing Pt. The Pt_r-PS SJMs can exhibit directional motion pushed by the Pt in the various H₂O₂ solutions, and they show much higher motion speeds than the Pt-PS SJMs with smooth Pt surfaces at the same H₂O₂ concentration. The Pt-pushed motion is related to the locally asymmetric catalytic reaction of the Pt coating on PS. The speed is also associated with the surface roughness of the Pt coating. The Pt film with a rough surface causes enhanced motion speed due to the improvement of reaction catalytic activity. This work presents a new route to enhancing the motor motion speed, which is of significance in designing micromotors with high-speed motion.