Surface Decoration And Tailoring Properties Of Porous Boron Nitride Nanofibers

By functional loading and regulating the structure and properties of simple nanomaterials from the microscopic level,the physical and chemical properties of the materials can be tailored and their applications can be broadened.Porous boron nitride nanofibers(BNNFs)not only inherit the excellent chemical stability,thermal stability and other properties of hexagonal boron nitride(h-BN),but also possesses the advantages of high specific surface area,high aspect ratio and good flexibility.The design and construction of new nanocomposites based on metal oxide nanoparticles/porous BN can combine the unique properties of metal oxide nanoparticles and porous BNNFs,which is of great significance to expand the application of porous BN.In this paper,metal oxide nanoparticles were loaded on porous BNNFs surface by solvothermal method,nanocomposites with excellent physical and chemical properties were constructed by changing the synthesis conditions.The main research contents are as follows:(1)Fe₃O₄nanoparticles(NPs)with average diameters of?7 nm were loaded on porous BNNFs via a solvothermal method to obtain a novel BNNF@Fe₃O₄nanocomposite that can efficiently adsorb Pb(?).The synthesized nanocomposites are in superparamagnetic state and exhibit a sensitive response to magnetic fields even it is very low.The synergistic adsorption process of Pb(?)on nanocomposites with different loading amount of Fe₃O₄NPs was studied.The strong electrostatic interaction between BNNFs and Pb(?)results in the initial rapid adsorption of Pb(?)on the surface of BNNFs,and the weak electrostatic force of Fe₃O₄leads to the subsequent adsorption of Pb(?)on Fe₃O₄,showing an interesting component-ratio related synergistic effect.The BNNF@Fe₃O₄nanocomposites with sparsely loaded Fe₃O₄NPs exhibit remarkable adsorption effect on Pb(?)with a maximum adsorption capacity of 203.75 mg/g in accordance with the Langmuir and the pseudo-second-order kinetic models.(2)A novel BNNF@CeO₂nanocomposite with high efficiency in oxygen reduction reaction(ORR)was synthesized by loading CeO₂NPs on porous BNNFs via a solvothermal method.Benefiting from the reduction atmosphere in the closed ethanol solution,the high concentration of oxygen vacancy can be introduced into the CeO₂NPs.By changing the solvothermal reaction time,the loading,size and oxygen vacancy of CeO₂NPs were regulated,and theirORR performance was regulated.The relationship between the defect oxygen vacancy andORR activity in CeO₂was revealed.Compared with pure CeO₂,theORR performance of BNNF@CeO₂nanocomposites has been significantly improved.(3)Using glycol as solvent,the porous BNNFs adsorbed with In(?)was reacted under solvothermal conditions to prepare In₂O₃/BNNFs composite.Although In₂O₃NPs were successfully prepared,the long-term solvothermal reaction of glycol will cause the destruction of the structure and morphology of BNNFs.Furthermore,the hollow In₂O₃nanotubes were prepared by using BNNFs as template,combining solvothermal and homogeneous precipitation method.BNNFs play an important template role in the growth of In₂O₃nanotubes.BNNFs with defect impurities provide a large number of active sites for the nucleation and growth of In₂O₃nanocrystals,and hollow tubular structure assembled by In₂O₃NPs is finally formed under the action of glycol.