Afterglow Materials-based Janus Nanomotors For Round-the-clock Degradation Of Biochemical Pollutants

Pathogenic bacteria（e.g.,E.coli）and endocrine disruptors（e.g.,17β-estradiol）are widely spread in nature through water as a medium,causing water pollution and environmental damage.Recenty,sewage treatment is faced with the problems of complex operation,poor effect and high cost,while micromotors have shown great potential in environmental treatment and restoration due to their nano-size effect and good motion performance.Micromotors driven by ultraviolet or visible light have the advantages of controllable motion speed,use of renewable and clean energy,and no toxic waste.However,light-driven micromotors still face the problems of short duration of photocatalytic reaction,low utilization efficiency of light energy,unsatisfactory photocatalyst performance and inability to recycle.Therefore,the design of visible light-driven micromotors to achieve efficient“around the clock”removal of microbial and chemical pollutants,which can be recycled and reused,has important scientific significance and practical value for water treatment and environmental governance.In the current study,IO/Si@ZGC-Au Janus micromotors（JMs）were synthesized through deposition of Zn Ga₂O₄:Cr³⁺（ZGC）on silica-coated Fe₃O₄ nanoparticles（IO/Si）and then sputter coating on one side with Au layers.Mannose-modified JMs（m JMs）of IO/Si@ZGC-Au-Man were prepared through amide reaction between mercaptoethylamine-modified JMs and carboxyl-modified mannose.The prepared JMs and m JMs were of core-shell Janus structures with the average diameters of 300 and 310 nm,respectively.JMs could be excited by ultraviolet（275 nm）and visible light（417 and 559nm）,and the self-electrophoretic motion mechanism of JMs was confrimed by photocurrent and electric field simulations.Under the excitation of a light emitting diode（LED）,JMs moved at a speed of 5.53μm/s in pure water,and continued to move for about 3 h after turning off the LED.The ability of JMs to degrade 17β-estradiol was investigated by high performance liquid chromatography.The degradation rate reached 81%after 3 h of illumination,and the degradation effect was 12.2%after retention in the dark for 3 h.In vitro antibacterial experiments showed that m JMs with 25%of mannose grafting had the best antibacterial effect of about 98.1%,and the motion promoted bacterial adhesion in the dark.The recycling of JMs and m JMs were realized under magnetic field,and the movement speed,degradation ability and bacterial removal effect had good repeat stability.In summary,the paper studied one type of visible light-driven afterglow materials-based Janus nanomotors to achieve“around the clock”degradation of biochemical pollutants,showing great potential in wastewater treatment and environmental remediation.