High-efficiency removal of organic pollutants by visible-light-driven tubular heterogeneous micromotors through a photocatalytic Fenton process.

Light-driven micromotors that can be remotely controlled by irradiation have environmental remediation applications. Herein, we describe a facile one-step hydrothermal method for synthesizing visible-light-driven heterogeneous micromotors by simultaneously depositing photocatalytic g-CN and magnetic FeO nanoparticles on kapok fiber (KF) templates (g-CN-FeO@KF). These microdevices exhibit precisely controlled motion in the presence of hydrogen peroxide (HO) under visible light via a bubble recoil mechanism. The present g-CN-FeO@KF units display-two simultaneous locomotion modes: linear and self-rotation. The velocity of these micromotors can be controlled by multiple approaches, such as by changing the HO concentration or visible light intensity. The photocatalytic propulsion of these microdevices can be conveniently switched on or off by regulating the incident light. As a proof-of-concept, g-CN-FeO@KF micromotors were applied to the degradation of Rhodamine B (RhB). On the basis of a combination of photocatalytic Fenton oxidation and enhanced micro-mixing/mass transfer in the solution induced by self-propulsion and self-rotation, these g-CN-FeO@KF micromotors enable much more efficient degradation of RhB compared with stationary systems. The magnetic nature of this material additionally allows convenient collection and recycling of the micromotors. The synthesis process can be easily scaled up and therefore may have the potential to fabricate self-propelled micromotors for practical applications.