Reversed Janus Micro/Nanomotors with Internal Chemical Engine

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Self-motile Janus colloids are crucial for microtechnology and understanding artificial micro/nanoswimmers.
• Developing efficient and controllable micro/nanomotors is an active area of research.

Purpose of the Study:

• To present novel micro/nanomotors with an internal catalytic chemical engine.
• To investigate the size-dependent motile behavior of these reversed Janus particles.

Main Methods:

• Fabrication of mesoporous silica (mSiO2)-based hollow particles with embedded platinum (Pt) catalyst.
• Suspension of particles in aqueous hydrogen peroxide (H2O2) solution.
• Observation and analysis of particle motion using varying particle diameters (500 nm, 1.5 µm, 3 µm).
• Theoretical modeling based on self-phoresis to rationalize motion direction.

Main Results:

• 500 nm particles showed enhanced diffusion.
• 1.5 µm and 3 µm particles exhibited self-phoretic motion towards the nonmetallic part.
• 3 µm particles displayed altered morphology, propulsion via bubble nucleation/ejection, and reversed motion direction.

Conclusions:

• The reversed Janus micro/nanomotors demonstrate size-dependent propulsion mechanisms.
• Internal catalytic engines offer a new approach for designing artificial micro/nanoswimmers.
• Understanding these mechanisms advances microtechnology applications and fundamental knowledge of micro-swimming.