Functionalization And Application Of Hexagonal Boron Nitride Nanomaterials

Hexagonal BN (h-BN) with a wide band gap (-5.9eV) has many attractive properties for potential applications, such as high temperature stability, high mechanical strength, a large thermal conductivity, and a low dielectric constant. Recently, h-BN has received a great deal of attention as a promising material in composites, photo-luminescence materials, electrical materials and so on. Modifying, doping and compositing are the most effective ways to enlarge the application of BN. In this article, modified, doped and composited tubulose or sheet-like hexagonal BN materials related to the electrochemical and luminescence properties are studied. The main contents are summarized as follows:1. A new type of amperometric biosensor, based on the BNNTs-Pani-Pt hybrids with Pt nanoparticle decorated on polyaniline(Pani)-wrapped boron nitride nanotubes (BNNTs), is fabricated. The microstructure and chemical bonding state of the Pt modified Pani-wrapped BNNTs hybrids are systematically investigated. It is shown that π interactions take place between BNNTs and polyaniline (Pani) located at nitrogen atoms from BNNTs and C atoms from Pani, resulting in water solubility of the Pani wrapped BNNTs hybrids. It is the key step for the Pt nanoparticle to homogeneously modify the water-soluble Pani-functionalized BNNTs for the development of the amperometric glucose enzyme biosensor. The glucose oxidase can be successfully immobilized in BNNTs-Pani-Pt hybrids. The resulted amperometric glucose biosensor based on the BNNTs-Pani-Pt hybrids exhibits a fast response time (within3s) and a linear calibration range from0.01to5.5mM with a high sensitivity and low detection limit of19.02mAM-1cm-2and0.18μM glucose (S/N=3). The developed biosensor exhibits excellent acid stability and heat resistance. Surprisedly, the relative activity of GC/BNNTs-Pani-Pt-GOD electrode keeps almost no change in the range from3to7for pH value. When the temperature is less than35℃, it seems that the activity is partially locked. With the temperature increasing, the activity increases until it is up to60℃. We owe this to the effect of electrostatic field and hydrophobia of BNNTs. The GC/BNNTs-Pani-Pt hybrid biosensors would open new horizons for fabrication of biosensors and biocatalysts.2. A new kind of cerium doped boron nitride which can emit bright blue light based on4f-5d transition of Ce3+ion has been successfully prepared via simple inducing heating route. SEM and TEM results show that the as-prepared cerium doped boron nitride is sheet-like with an average diameter of200-300nm and a thickness of30-50nm. The band gap of xCe-BN reduces from4.37to3.31eV with the doping concentration increasing due to the structural modification of xCe-BN by cerium doping. The paramagnetic centers of pure BN and1%Ce-BN samples are studied using EPR method. The difference of paramagnetic centers between pure BN and1%Ce-BN samples implies that with Ce doped into BN, the type of electron paramagnetic centers in1%Ce-BN are different compared with that of pure BN. When the molar ratio of cerium to boron (Ce/B) in the precursor is1%, the as-prepared cerium doped boron nitride exhibits the brightest blue light under308nm UV light with two emission centers at404and428nm. This small Stokes shift reveals the weak covalency between Ce3+with BN host. The strong blue-light emission is expected to be as an efficient phosphors and applicated in lighting source.3. Boron nitride nanosheets with thickness of40nm and diameter of100-200nm are used as anode materials in lithium batteries. BN/P25and BN/TiO2anode composites are also employed in lithium batteries. Interesting enough that the capacities of BN/P25and BN/TiO2are2and1.3times larger as that of P25and TiO2samples, respectively at the current of10mAg-1. Nanohybrids of Ni functionalized BN sheets with TiO2improve the battery storage performance further, which can be ascribed to the improving of electrical conductivity for the metal Ni functionalization.