WANG Yukuan, XIE Qi, XU Leilei, LUO Ming, MOU Fangzhi

(State Key Laboratory of Advanced Technology for Materials Synthesis and Processing,International School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China)

Abstract:In order to study the positive phototaxis behavior of core-shell structured magnetic bead@TiO2 (MB@TiO2) micromotors, the surface of magnetic beads was coated with a thin TiO2 layer using ultrasonic-assisted sol-gel method to prepare core-shell structured MB@TiO2micromotors.The structure, morphology，and motion behaviors of MB@TiO2micromotors were characterized by scanning electron microscope(SEM), transmission electron microscope(TEM)，and optical microscope.The results show that the MB@TiO2 micromotors have a core-shell structure. The asymmetric photocatalytic reactions between the light-irradiated surface and the shadowed surface of the MB@TiO2 micromotors under ultraviolet light is used to make the photocatalytic products of hydrogen peroxide unevenly distribute on both sides of the micromotor to form a concentration gradient. The diffusiophoretic force produced by the H+ concentration gradient pointing to the light source predominates, and thus the MB@TiO2 micromotors exhibit positive phototaxis toward the light source. Due to its positive phototaxis behavior, the MB@TiO2 micromotors can easily overcome gravity to climb obstacles and swim in complex terrain or bulk water far from the substrate. In addition, combining the photocatalytic activity of the TiO2 shell and the magnetic responseof the MB core, the MB@TiO2 micromotors are expected to be used as the “swimming” photocatalystsin environmental remediation witheasy magnetic separation in the future.

Keywords: micro-nanomotor; magnetic bead; phototaxis; photocatalysis

中图分类号：TB34                               文献标志码：A

文章编号：1008-5548(2020)04-0009-06

DOI:10.13732/j.issn.1008-5548.2020.04.002

收稿日期： 2020-02-19，修回日期：2020-02-25，在线出版时间：2020-05-07 14:16。

基金项目：国家自然科学基金项目，编号：21875175，21975195，21705123；湖北省自然科学基金项目：编号：2019CFA048。

第一作者简介：王玉宽(1994—)，男，硕士研究生，研究方向为微纳米马达。E-mail：838654411@qq.com。

通信作者简介：牟方志(1981—)，男，博士，副研究员，博士生导师，研究方向为微纳米马达。E-mail：moufz@whut.edu.cn。