Bilayer Tubular Micromotors for Simultaneous Environmental Monitoring and Remediation

Abstract

There are two main aspects of environmental governance including monitoring and remediation, both of which are essential for environmental protection. Self-propelled micro/nanomotors (MNM) have shown promising potential for achieving on-demand tasks in environmental field, including environmental sensing and pollutant removal or degradation. However, most of the current MNM used in environmental protection can hardly accomplish the two major tasks of both monitoring and pollutant degradation. Hereby, we present a bubble-propelled mesoporous silica-coated titania (TiO₂@mSiO₂) bilayer tubular micromotor with platinum (Pt) and magnetic Fe₃O₄ nanoparticles modified on their inner walls. The outer mesoporous silica (mSiO₂) layer can effectively adsorb and collect the pollutants, and the adsorption capacity of the TiO₂@mSiO₂ tube is about 3 times higher than that of the TiO₂ tube due to the presence of mSiO₂ shell. By magnetic manipulation, the micromotors can be recovered to release the collected pollutant for precise analysis of the composition of the pollutants, such us pollutant molecule identification by surface-enhanced Raman scattering. The active motion and photocatalytic TiO₂ inner layer of the micromotors can greatly enhance the degradation rate of the model pollutant rhodamine 6G (R6G). Our results show that within 30 min, up to 98% of R6G can be degraded by the motors. The successful demonstration of the TiO₂@mSiO₂ bilayer tubular motors for simultaneous environmental monitoring and pollutant degradation paves the way for future development of active and intelligent micro/nanorobots for advanced environmental governance.