Synthesis Of Carbon Or Iron Doped Boron Nitride Materials And Their Adsorption And Photocatalytic Properties

Boron nitride?BN?is a kind of non-metallic semiconductor material.The hexagonal boron nitride?h-BN?has a lamellar crystal structure,which is the most stable at room temperature.Compared with the zero-band-gap graphene materials,the hexagonal boron nitride materials have a tunable wide-band band-gap band structure,showing a thermal stability beyond that of carbon materials,and have good performances such as antioxidant activity and chemical inertness.The unique physical and chemical properties such as high-temperature thermal conductivity,excellent dielectric properties,wave transmission and neutron absorption,making it useful as additives of composite materials to improve the comprehensive properties of materials.In addition,the porous structure of h-BN material has a high specific surface area and outstanding adsorption activity.It has a wide application prospect in the field of catalyst support,adsorption catalysis,biomedicine and other extreme environmental conditions.In this paper,the synthesis,adsorption and photocatalytic properties of hexagonal boron nitride,BCN material and Fe/BN material were studied.At the same time,the synthesis and adsorption properties of BN/PAN hybrid nanofibers was studied also.The specific contents and research results are as follows:?1?Using boric acid as the boron source and melamine as nitrogen source,the boron nitride precursor?2H₃BO₃·C₆N₆H₆?with supramolecular structure was prepared at a relatively low temperature.Then it was mixed with different proportion of peanut shell biomass charcoal powder.Under the atmosphere of nitrogen protection,the carbon doped BCN material was obtained by heat treatment of the mixed powder at 1000?for 4 h.The composition,structure and morphology of the composite were analyzed by X-ray diffraction analysis,infrared spectroscopy test and scanning electron microscope.Morever,The adsorption property for methyl orange?MO?was tested and the adsorption mechanism was explored.The results show that BCN material obtained by high temperature pyrolysis realized the effective combination of h-BN and carbon material.Among them,the specific surface area of BCN-₇ is 837.7m²/g.Scanning electron microscope analysis showed that the sample of BCN-₇ has a porous lamellar structure with a thickness of about 5 nm.The results showed that BCN-₇ has the best adsorption efficiency for methyl orange,which could reach 97%in 40 min and 99%in 60 min.?2?A new iron modified Fe/BN material was prepared by heat treatment with boric acid,melamine and nanometer Fe₃O₄ powder of different quality.By means of X-ray diffraction powder analysis,infrared spectroscopy test,electron microscope analysis,UV-visible diffuse reflection,specific surface area test and X-ray photoelectron spectroscopy analysis,the phase composition,atomic bonding state and photocatalytic performance of Fe/BN material were mainly analyzed.Under the condition of heat treatment,most of Fe₃O₄ powder were reduced to iron nanoparticles.The synthesized BN₃ sample has a porous tubular structure,and its wall is composed of Fe nanoparticles with a size of about 50 nm.The UV absorption spectrum shows that the visible absorption wavelength of BN₃ material has red shift to 550 nm.The photocatalytic activity of Fe/BN material was studied through the degradation of methyl orange under visible light.The results shows that BN3 has the best photodegradation activity for MO.Under visible light irradiation,99.1%MO can be rapidly degraded in 45 min.?3?Spinning solutions with different boron nitride contents were obtained by changing the mass ratio of PAN to the additive boron nitride by using dimethylformamide?DMF?as the organic solvent.Then,BN/PAN hybrid nanofibers was obtained by electrostatic spinning for 2 h at 18 kV.The BN/PAN hybrid nanofibers was characterized and analyzed by X-diffraction powder analysis,infrared spectroscopy,electron microscope analysis,specific surface area test and thermal analysis.It is found that boron nitride can be evenly dispersed in BN/PAN hybrid nanofibers,with reduced crystal size.the morphology of hybrid nanofibers presents convex structure.The instability of spinning causes the nanofibers to form a disordered arrangement and even to form a shuttle bead.The thermal stability of hybrid nanofibers with boron nitride was improved significantly.At the same time,the specific surface area and total pore volume of the composite nanofibers was increased 2 and 3.2 times respectively with the addition of boron nitide.There is a concentrated aperture distribution around 2?4 nm,which is helpful to improve its application in the fields of adsorption and photocatalysis.