Light‐driven micromotors have stimulated considerate interests due to their potentials in biomedicine, environmental remediation, or serving as the model system for non‐equilibrium physics of active matter. Simultaneous control over the motion direction and speed of micro/nanomotors is crucial for their functionality but still difficult since Brownian motion always randomizes the orientations. Here, a highly efficient light‐driven ZnO/Pt Janus micromotor capable of aligning itself to illumination direction and exhibiting negative phototaxis at high speeds (up to 32 µm s−1) without the addition of any chemical fuels is developed. A light‐triggered self‐built electric field parallel to the light illumination exists due to asymmetrical surface chemical reactions induced by the limited penetration depth of light along the illumination. The phototactic motion of the motor is achieved through electrophoretic rotation induced by the asymmetrical distribution of zeta potential on the two hemispheres of the Janus micromotor, into alignment with the electric field. Notably, similar phototactic propulsion is also achieved on TiO2/Pt and CdS/Pt micromotors, which presents explicit proof of extending the mechanism of dipole‐moment induced phototactic propulsion in other light‐driven Janus micromotors. Finally, active transportation of yeast cells are achieved by the motor, proving its capability in performing complex tasks.

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Directional motion in response to specific signals is critically important for micro/nanomotors in precise cargo transport, obstacle avoidance, collective control, and complex maneuvers. In this work, a kind of isotropic lightdriven micromotor that is made of hedgehog-shaped TiO 2 and functional multiwall carbon nanotubes (Hs-TiO 2 @FCNTs) has been developed. The FCNTs are closely entangled with Hs-TiO 2 and form a close-knit matrix on the surface of Hs-TiO 2 , which facilitates the transfer of electrons from Hs-TiO 2 to FCNTs. Due to the high redox potential of Hs-TiO 2 , excellent electron−hole separation efficiency by the addition of FCNTs, and isotropic morphology of the micromotor, these Hs-TiO 2 @FCNT micromotors show phototactic and fuel-free propulsion under unidirectional irradiation of UV light. It is the first time to demonstrate isotropic micromotors that are propelled by self-electrophoresis. The isotropy of Hs-TiO 2 @ FCNT micromotors makes them immune to the rotational Brownian diffusion and local flows, exhibiting superior directionality. The motion direction of our micromotors can be precisely tuned by light and a velocity of 8.9 μm/s is achieved under 160 mW/cm 2 UV light illumination. Photodegradation of methylene blue and active transportation of polystyrene beads are demonstrated for a proof-of-concept application of our micromotors. The isotropic design of the Hs-TiO 2 @FCNT micromotors with enhanced photocatalytic properties unfolds a new paradigm for addressing the limitations of directionality control and chemical fuels in the current asymmetric lightdriven micromotors.

Advances in the versatile design and synthesis of nanomaterials have imparted diverse functionalities to Janus micromotors as autonomous vehicles. However, a significant challenge remains in maneuvering Janus micromotors by following desired trajectories for on-demand motility and intelligent control due to the inherent rotational Brownian motion. Here, we present the enhanced and robust directional propulsion of light-activated Fe3O4@TiO2/Pt Janus micromotors by magnetic spinning and the Magnus effect. Once exposed to a low-intensity rotating magnetic field, the micromotors become physically actuated, and their rotational Brownian diffusion is quenched by the magnetic rotation. Photocatalytic propulsion can be triggered by unidirectional irradiation based on a self-electrophoretic mechanism. Thus, a transverse Magnus force can be generated due to the rotational motion and ballistic motion (photocatalytic propulsion) of the micromotors. Both the self-electrophoretic propulsion and the Magnus force are periodically changed due to the magnetic rotation, which results in an overall directed motion moving toward a trajectory with a deflection angle from the direction of incident light with enhanced speed, maneuverability, and steering robustness. Our study illustrates the admirable directional motion capabilities of light-driven Janus micromotors based on magnetic spinning and the Magnus effect, which unfolds a new paradigm for addressing the limitations of directionality control in the current asymmetric micromotors.

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