Visible-Light-Driven WO 3 –Silver Nanoparticle Micromotors with Concentration-Dependent Propulsion for Enhanced Pollutant Degradation

In natural ecosystems, many microorganisms (such as cyanobacteria) possess limited self-propulsion capabilities upon light exposure. However, their swarms exhibit synergistic phototactic behavior through intercellular chemical signaling that enhances phototaxis. In the field of micromotors, achieving asynchronous motion between individual micromotors and their swarms has remained a persistent challenge. Herein, we report a visible-light-driven micromotor composed of WO 3 microrods modified by silver nanoparticles at the nanoscale, which exhibits the concentration-dependent motion behavior. At low concentrations, individual micromotors exhibit Brownian motion, while at high concentrations, chemical signaling leads to the formation of swarms and collective phototaxis. This phenomenon arises from the electro-osmotic flow and self-diffusiophoretic propulsion mechanisms based on the self-established ion concentration gradients. Furthermore, the WO 3 /Ag micromotor swarm demonstrates efficient pollutant degradation, indicating great potential for environmental remediation.