Synthesis And Properties Of Micro/Nano Structured Boron Nitride

In recent years, hexagonal boron nitride (h-BN) because of its excellent physical and chemical properties attracted the interest of many research workers. BN nanomaterials have been synthesized by various synthetic methods, but the price of raw materials, synthesis conditions, product yield, product purity, morphology control has been restricting the boron nitride research and industrial production. For these problems can not only help to understand study the formation mechanism of boron nitride and boron nitride can improve application performance nanomaterials. Therefore, the study of boron nitride meet people, thermal stability, excellent mechanical strength, high thermal conductivity and electrical conductivity of the demand for chemically inert material.A general strategy was developed to synthesize shape-controllable hexagonal boron nitride micro/nanoparticles using carbon sphere as a template at 1100℃ under nitrogen atmosphere. The obtained products were characterized by X-ray diffraction techniques, X-ray photoelectron spectroscopy, scanning electron microscopy and nitrogen-sorption analysis. The results revealed that the morphologies of the products could be well tailored, such as nanofibers, nanospheres, walnut-like nanospheres, nanorods and nanosheets by regulating the amount of glucose and nitrogen flow rate. A possible growth mechanism accompanied with the effects of h-BN on crystal nucleation and growth was preliminarily proposed for the formation of the controllable structures. The amount of carbon spheres was 20wt%, the other conditions unchanged, the BN powder prepared at nitrogen flow rate 0.1L/min was composed of nanosheets with about 30nm in diameter. When the nitrogen flow rate was increased to 0.2L/min, nanosheets occurred accumulation along the direction of nitrogen. At nitrogen flow rate 0.3L/min, microrods of self-assembled nanosheets were obtained. The amount of mesoporous silica spheres was 45wt%, the other conditions unchanged, various BN were synthesized simply by adjusting the nitrogen flow rate. The powder prepared at nitrogen flow rate 0.1L/min was composed of microspheres of self-assembled nanosheets. The morphology changed from microspheres to blocky structure when the increase nitrogen flow rate to 0.3L/min. A different growth mechanism accompanied with the effects of mesoporous silica spheres and carbon balls. The prepared boron nitride nanosheets with an average diameter of 30 nm have an ultraviolet absorption peak around 210 nm and well dispersed in aqueous solution over 24 hours. The as-prepared BN nanosheets showed high specific surface area of 118.8 m2g-1 and a mesoporous volume of 0.4 cm3g-1. The BN fluorescence spectroscopy shows that there are four main emission bands at 436.5,454.4,486.7 and 616.5nm. It is found that BN nanosheets have a strong effect on fluorescence quenching of Rhodamine-B (RB) and fluorescence enhancement of Alizarin red S (ARS). The interesting and meaningful achievements confirm its potential applications in sensitive optical components, the fields of biosensor and photocatalytic reaction.