Photothermal-Propelled Au-CeO₂ Micromotors for Synergistic Photocatalytic-Photothermal Antibacterial Systems

Facing the great challenge for efficient utilization of solar light, the design of photothermal-propelled micromotors is significant for converting optical energy into thermal energy to achieve the in situ manipulated motion. Assisted by the photothermal-propelled function, a synergistic photocatalytic-photothermal antibacterial system is successfully constructed in this work, based on the Au-CeO₂ micromotor. The selective growth of CeO₂ nanoparticles on the surface of Au nanorods (NRs) is achieved with the adjustable Au exposure ratio. The strong interaction of CeO₂ with Au NRs realizes the enhanced visible light harvesting and the promoted photo-induced charge separation. Especially, the self-induced thermophoretic force on asymmetric lollipop-like L-Au-CeO₂ with higher Au exposure ratio is more powerful than that on symmetric core-shelled CS-Au-CeO₂ and dumbbell-like D-Au-CeO₂. As a result, its local temperature gradient is greater and thus realizes the in situ manipulated motion with higher velocity and stronger directionality. It further facilitates the contact with bacteria and promotes the synergistic photocatalytic-photothermal antibacterial performance for the probe bacteria of Escherichia coli. This powerful photothermal-propelled Au-CeO₂ micromotor shows significant potential for the microorganism control in biomedical and environmental applications.