Unraveling Charge Transport in Heterostructured Nanomotors for Efficient Photocatalytic Motion

Photocatalytic micro/nanomotors have emerged as promising tools for environmental remediation, biosensing, and targeted delivery. To enhance their light-driven propulsion, significant efforts have focused on engineering semiconductor heterostructures, which promote charge separation. However, a clear understanding of how these architectures govern photocatalytic mechanisms and influence motion performance remains limited. Here, we design a visible light-responsive nanomotor based on a Fe₂O₃-Pt-TiO₂ trilayered heterostructure, combining narrow-bandgap α-Fe₂O₃ and wide-bandgap TiO₂ with an intermediate Pt layer. Remarkably, Fe₂O₃-TiO₂ nanomotors without the Pt layer exhibit only modest propulsion under visible light, whereas the inclusion of Pt significantly enhances their motility. Through advanced techniques, including in situ synchrotron radiation-based near-ambient pressure X-ray photoelectron spectroscopy and transient absorption spectroscopy, we reveal that Pt serves as an efficient electron mediator, enabling directional charge transfer across the heterojunction. This study provides fundamental insights into charge transport in multicomponent nanomotors and introduces a rational strategy for designing efficient photoactive systems.