Broadband-Responsive UiO-PPy MOF Micromotors for 3D Motion and Selective Dye Separation

Light-driven micro/nanomotors (MNMs) have emerged as promising candidates for environmental remediation and related applications. However, conventional light-driven systems often suffer from poor light-harvesting efficiency, limited motion modes, and high fabrication costs, which hinder their practical employment. Herein, we developed a novel class of MNMs capable of efficient propulsion across a broad UV-Vis-NIR spectral range. These hybrid motors are based on the robust metal-organic framework UiO─66 and functionalized with polypyrrole (PPy) through three distinct integration strategies: in situ polymerization, pre-loading, and post-synthetic modification. The resulting MNMs enable tunable motion behaviors and catalytic performance. Among them, UiO-PPy-PreInc motors exhibited outstanding photothermal response and achieved ultrafast propulsion speeds up to 1717 ± 265 µm/s under UV light irradiation. Comprehensive trajectory analyses revealed dynamic 3D motion, including directional steering and adaptive velocity control. A custom-built optical microscopy tracking system enabled real-time, high-resolution monitoring of their behavior, which was previously achievable only through computational simulations. Furthermore, the synergistic combination of UiO─66's high surface area and porosity with PPy's photothermal and charge transport properties facilitated highly efficient methyl orange degradation (99%) and selective dye separation (90%) under light activation. This work establishes a versatile and scalable platform for multifunctional MNMs with integrated pollutant removal and resource recovery capabilities, paving the way toward advanced water purification technologies.