Pt-TiO2 Bilayered Hemispherical Nanoshells with Tunable Pt Distribution for Chemically Self-Propelled Colloidal Motors

Abstract

The control of colloidal motors’ motion is crucial for their practical applications. The modulation of the active component distribution on the motors is one of the effective routes to controlling their motion but still in challenge. Here, Pt-TiO2 bilayered hemispherical nanoshells (BHNSs) with different Pt distributions are designed and fabricated via etching an organic colloidal template and depositing TiO2 and Pt in different angles and sequences. The obtained nanoshells include the BHNSs with complete Pt outer and inner layers (or TiO2/Pt and Pt/TiO2 BHNSs) and the partially bilayered hemispherical nanoshells (P-BHNSs) with incomplete Pt outer and inner layers (or TiO2/Pt and Pt/TiO2 P-BHNSs). All these Pt-TiO2 BHNSs can move, in H2O2-containing solutions, in Pt coating-pushed way, exhibiting Pt distribution-dependent motion modes, speeds, and postures. Typically, the TiO2/Pt (or Pt/TiO2) BHNSs move at the posture of the opening forward (or backward), exhibiting well-directional motion with a relatively low speed, while the TiO2/Pt (or Pt/TiO2) P-BHNSs move at the posture of the opening forward (or backward) with a tilted angle, showing the quasi-circular motion with a relatively high speed. A Pt coating catalysis-induced diffusiophoresis mechanism is proposed, which can well describe the Pt distribution-dependent self-propelled behaviors. This work provides a flexible route for fabricating Pt distribution-tunable nanoshells and deepens our understanding of Pt distribution-dependent chemically self-propelled behaviors.