Experimental and Theoretical Studies Suggesting the Possibility of Metallic Boron Nitride Edges in Porous Nanourchins

Abstract

We first describe the synthesis of novel and highly porous boron nitride (BN) nanospheres (100-400 nm o.d.) that exhibit a rough surface consisting of open BN nanocones and corrugated BN ribbons. The material was produced by reacting B2O3 with nanoporous carbon spheres under nitrogen at ca. 1750 degrees C. The BN nanospheres were characterized using scanning electron microscopy, high-resolution electron microscopy, and electron energy loss spectroscopy. The porous BN spheres show relatively large surface areas of ca. 290 m2/g and exhibit surprisingly stable field emission properties at low turn-on voltages (e.g., 1-1.3 V/microm). We attribute these outstanding electron emission properties to the presence of finite BN ribbons located at the surface of the nanospheres (exhibiting zigzag edges), which behave like metals as confirmed by first-principles calculations. In addition, our ab initio theoretical results indicate that the work function associated to these zigzag BN ribbons is 1.3 eV lower when compared with BN-bulk material.

Electronic properties and relative stabilities of heterogeneous edge-decorated zigzag boron nitride nanoribbons

“…However, due to the large ionicity of the BeN chemical bond, BNNRs exhibit some unique properties that are different compared to the corresponding properties of GNRs. Zigzag BNNRs (zBNNRs) with bare edges are magnetic semiconductors and their band gap decreases with the ribbon width, which was confirmed both theoretically [8e11] and experimentally [12]. When the B edges were passivated with H atoms, a half-metallic behavior was observed [13,14].…”

First principle study of unzipped boron nitride nanotubes

“…The reported electronic properties of bare carbon ribbons [22], and H-terminated BN and BCN ribbons [23], demonstrating the main role of the edge states on the energy gap of the system. Although the thermal and chemical stability of bare BNNRs have not been considered, their existence is supposed in the surface of nanospheres during electron emission [24]. Now we investigate the electronic properties of partially rolled up BNNR in the creation process of a BNNT and the effect of curvature on the dangling bonds.…”

“…Therefore curling of surface does not change the electronic properties of system and curved ABNNR also exhibits metallic feature. It has been claimed that these dangling bands play a key role in the field-emission characteristics of the spiky BN structures synthesized experimentally [24]. Both experimental and theoretical results propose that active edges are needed to observe stable field emission.…”

One pot synthesis of mesoporous boron nitride using polystyrene-b-poly(ethylene oxide) block copolymer

“…[8][9][10][11][12][13][14][15] However, for most of these applications, the precise control of pore size/ distributions, wall thickness, pore shape, specic surface area and surface chemistry is demanded. To achieve such goals, two major strategies known as hard and so templates are normally utilized.…”