Preparation And Application Of Bi-based Micromotor

The micro-nano motor has shown great potential in biomedicine and environmental governance due to its unique autonomous movement,and has received widespread attention.We combined the micro-nano motor with BiOX?X=Bi,I?photocatalyst,which significantly improved the degradation efficiency of the photocatalyst.Compared with the static degradation of traditional photocatalysts,the Bi-based micromotor could promote the mass transfer of the solution through autonomous movement,increases the chance of contacting the catalyst with pollutants,and increases the degradation rate of pollutants.Nanozymes not only have the specificity of natural enzymes,but also overcome the shortcomings of natural enzymes,such as easy inactivation and difficulty in purification,so they replace natural enzymes for the detection of special substances.Therefore,Using micromotors to combine photo-Fenton reagents and photocatalysts with peroxidase mimic activity to obtain new composite materials with excellent photo-Fenton activity and coexistence of detection and degradation.The detailed research contents are as follows:1?A new type of 3D Fe³⁺doped BiOBr-based magnetic micromotor was prepared by simple solvothermal method and photoreduction method.The micromotor has excellent photo-Fenton catalytic activity and can efficiently degrade organic pollutants.SEM,TEM,XRD,XPS and EDS were used to analyze the Fe³⁺-doped BiOBr-based magnetic micromotor in terms of its crystal structure,micro-morphology and performance.The experimental results show that the Fe³⁺-doped BiOBr-based magnetic micromotor retains the spherical structure of BiOBr,and the magnetic Fe₃O₄ particles are evenly distributed on the surface,while the Mn₃O₄ is half-coated on one end to form a Janus ball with a specific surface area of 32.06 m²g^-1.The saturation magnetization strength of 8.95 emu g^-1 is sufficient for the control and recycling of micromotors.Using hydrogen peroxide as a reagent and fuel,Fe³⁺-doped BiOBr-based micromotors show extremely high degradation efficiency of methylene blue in the solar photo-Fenton system even under neutral pH conditions,almost 4 times that of BiOBr.In 5%H₂O₂ solution,the speed of the micromotor can reach 214.7±19.4?m s^-1,and the velocity increases with the increase of H₂O₂ concentration.The factors affecting the Fenton reaction of sunlight,including Fe³⁺doping amount,pH,H₂O₂ concentration,autonomous movement and mechanical agitation,showed that the Fe³⁺doping amount was 0.11 mmol,pH=7,and the H₂O₂ concentration was 3%,the micromotor has the best degradation effect,and nearly 97%of the methylene blue is degraded within 50 min.The degradation effect of the micromotor's autonomous movement is better than mechanical stirring.This research provides new insights into the preparation of micromotors for water purification applications based on the solar photo-Fenton reaction.2?Using natural kapok as a biological template,a BiOI/CoMn₂O₄ micromotor with peroxidase-like activity and photocatalytic performance was prepared.The phase analysis,morphological observation and physical properties of BiOI/CoMn₂O₄micromotors were characterized by XRD,SEM and so on.The results indicate that the BiOI/CoMn₂O₄ micromotor maintains the hollow asymmetric tubular structure of kapok,the BiOI microspheres are evenly loaded on the Al₂O₃ microtubes obtained by impregnating calcined kapok,and the CoMn₂O₄ nanospheres are loaded on the BiOI nanosheets.It can be known from the analysis of the movement of the micromotor that it could move in a lower concentration of H₂O₂.The speed and traction force of the micromotor in 0.5%H₂O₂ are 37.65±0.87?m s^-1 and 17.45 pN,respectively,and the movement speed follows the concentration of H₂O₂ increases.Studies on the activity of nano-enzymes have observed that BiOI/CoMn₂O₄ micromotor has simulated peroxidase mimic activity.The BiOI/CoMn₂O₄ micromotor showed the strongest peroxidase mimic activity when the incubation time of 10 min,pH=5,temperature of 40 ^oC,BiOI/CoMn₂O₄ concentration of 7 mg/L,H₂O₂ concentration of10 mM and TMB concentration of 6 mM.In addition,BiOI/CoMn₂O₄ micromotor has a strong specificity for hydroquinone,the linear range of detection is 0-120?M,and the detection limit is 0.58?M.Moreover,the BiOI/CoMn₂O₄ micromotor has a good photocatalytic effect on hydroquinone.When the concentration of Bi³⁺is 30 mM and the concentration of H₂O₂ is 1%,the degradation efficiency of hydroquinone reaches more than 90%within 180 min.The degradation rate under autonomous movement is higher than that during mechanical stirring.This study provides a way for the detection and degradation of contaminant in water.