Fabrication Of Core-shell Nanostructured Magnetoelectric Composite Materials And Their Catalytic Effects

On the basis of ferroic materials,multiferroic materials have attracted wide attention because of their ability to achieve the coupling between different ferroics.The traditional single-phase multiferroic materials possess weak magnetoelectric coupling effect.The twophase combination between ferroelectric and ferromagnetic materials is expected to achieve strong magnetoelectric coupling.This paper fabricated core-shell nanostructured magnetoelectric composite material and achieved the coupling between magnetoelectric effect and electrochemical reaction to realize the multifunctional synergistic effect of magneto-elasticelectricity-electrochemistry.The magneto-catalytic performance of dye solution was investigated by applying external AC magnetic field.In this paper,BiFeO3 shell was coated on the surface of CoFe2O4 core by sol-gel method to fabricate core-shell nanostructured magnetoelectric material CoFe2O4-BiFeO3.The highly obvious interface characteristics between two different phases ensure the strong contact at the atomic level,which is beneficial to the stress transmission within this composite material and is expected to achieve strong magnetoelectric effect.The coupling of magnetoelectric effect and electrochemical reaction is able to obtain special characteristics.It will generate strong oxidizing active free radicals in the aqueous solution and therefore be used in the catalytic degradation of dye wastewater.This paper carried out the following researches with the combination of material fabrication,experimental characterization and performance testing.Firstly,the highly crystalline BiFeO3 nanoparticles were prepared by sol-gel method,and therefore the piezo-catalytic performance on the degradation of dye solution was explored under external ultrasonic vibration.This research revealed that when ultrasonic vibration was applied,1.0 g/L BiFeO3 nanoparticles were able to almost completely degrade 10 mg/L rhodamine B dye solution within 2.5 hours.Besides,10 mg/L methyl orange and methylene blue dye solution could also be degraded by 1.0 g/L BiFeO3 nanoparticles within 3 hours.The complete degradation of dye solution further confirmed the excellent piezo-catalytic performance of BiFeO3 nanoparticles.Then spherical CoFe2O4 nanoparticles with uniform morphology were fabricated by hydrothermal method,and then followed by sol-gel method to coat CoFe2O4 core with BiFeO3 shell to fabricate core-shell nanostructured magnetoelectric composite material CoFe2O4BiFeO3.Its morphology,interface and other features were characterized and the piezo-catalytic performance was explored.When ultrasonic vibration was applied,1.0 g/L CoFe2O4-BiFeO3 nanoparticles were able to almost completely degrade 10 mg/L rhodamine B dye solution within 2.5 hours,and possessed excellent piezo-catalytic performance.Besides,10 mg/L methyl orange and methylene blue dye solution could also be degraded by 1.0 g/L CoFe2O4-BiFeO3 nanoparticles within 3 hours.Finally,the performance of magneto-catalysis of magnetoelectric composite material CoFe2O4-BiFeO3 was explored by changing the frequency and strength of the applied AC magnetic field.This research revealed that under external AC magnetic field of 1 kHz and 15.9 mT,1.0 g/L CoFe2O4-BiFeO3 nanoparticles could almost completely degrade 10 mg/L rhodamine B dye solution within 2 hours.Under the same magnetic field conditions,10 mg/L methyl orange and methylene blue dye solutions could also be degraded completely by CoFe2O4-BiFeO3 nanoparticles within 2.5 hours.Besides,when the strength and frequency of the external AC magnetic field were reduced,the degradation performance of dye solution would also be inhibited to varying degrees.