Visible light driven TiO2/Pt micromotor with directional motion

Abstract

Light-driven micromotors show transformative potential for biomedical and environmental applications due to their biocompatibility, sustainability, and energy efficiency. However, conventional systems that rely on ultraviolet or infrared light face critical limitations, including biotoxicity and thermal damage. We present a TiO₂/Pt Janus micromotor enabling highly efficient surfactant-free propulsion under visible light (455 nm) through synergistic bandgap engineering and asymmetric catalysis. Platinum-mediated Schottky junctions extend optical absorption into the visible spectrum, achieving active propulsion in pure water at low intensities of 30 mW cm⁻². Motion control is demonstrated through speed modulation via light intensity adjustment, real-time start-stop switching, and hydrogen peroxide co-catalyst acceleration. The micromotors maintain exceptional multi-cycle stability while achieving trajectory straightness. Compared to systems driven by 365 nm light, the enhancement in directional persistence is significant, enabling precise directional motion control through internal chemical propulsion mechanisms without depending on external fields or physical guides, thereby overcoming the rapid deactivation characteristic of conventional systems. This fuel-free design establishes a biocompatible microactuation platform with minimized thermal effects, enabling applications in targeted drug delivery, minimally invasive surgery, and environmental remediation. Our work advances visible-light-controlled micromotors toward practical implementation.