From 2-D to 0-D Boron Nitride Materials, The Next Challenge

Abstract

The discovery of graphene has paved the way for intense research into 2D materials which is expected to have a tremendous impact on our knowledge of material properties in small dimensions. Among other materials, boron nitride (BN) nanomaterials have shown remarkable features with the possibility of being used in a large variety of devices. Photonics, aerospace, and medicine are just some of the possible fields where BN has been successfully employed. Poor scalability represents, however, a primary limit of boron nitride. Techniques to limit the number of defects, obtaining large area sheets and the production of significant amounts of homogenous 2D materials are still at an early stage. In most cases, the synthesis process governs defect formation. It is of utmost importance, therefore, to achieve a deep understanding of the mechanism behind the creation of these defects. We reviewed some of the most recent studies on 2D and 0D boron nitride materials. Starting with the theoretical works which describe the correlations between structure and defects, we critically described the main BN synthesis routes and the properties of the final materials. The main results are summarized to present a general outlook on the current state of the art in this field.

Keywords: 2D materials; boron nitride; fluorescence; nanocomposites; quantum dots.

Figure 1

(A) hexagonal boron nitride structures. Layer distance and crystal parameter. (B,C) Different edge terminations. (D,E) different boron nitride shapes: BN nanotubes and BN fullerene. Copyright 2012 and 2014, with permission of refs, [7,8].

Figure 2

On top: Schematic diagram of exfoliation mechanism. Copyright 2015, with permission of [58]. On bottom: (a) TEM Images of the BN sheets produced by 0.1–0.2 mm balls; (b) the corresponding SAED pattern; (c,d) high-magnification TEM images; (e,f) TEM images of few-layer BN nanosheets (g) EELS spectra of the BN nanosheet. Copyright 2014, with permission of [57].

Figure 3

On the top: Schematic representation of a microfluidizer processor. Below: Low magnification TEM images: transparent regions indicated by arrows refer to a few layers of boron nitride nanosheets. Copyright 2012, with permission of [60].

Figure 4

On top: CVD grown h-BN film on Ni (111). (a) SEM, (b) AFM, (c) Raman, (d) UV–Vis characterizations. On bottom: HR-TEM characterization of h-BN grown on Ni (111) (a) and sapphire (c). Cross-sectional HR-TEM of h-BN on Ni (111) (b) and sapphire (d). Copyright 2019, with permission of [82].

Figure 4

On top: CVD grown h-BN film on Ni (111). (a) SEM, (b) AFM, (c) Raman, (d) UV–Vis characterizations. On bottom: HR-TEM characterization of h-BN grown on Ni (111) (a) and sapphire (c). Cross-sectional HR-TEM of h-BN on Ni (111) (b) and sapphire (d). Copyright 2019, with permission of [82].

Figure 5

Left: scheme of PLD system. Right: SEM image of h-BN/Ag(111)/SrTiO3(001) deposited by PLD. Copyright 2016, with permission of [84].

Figure 6

Growth of h-BN on Ni (111) by MBE. (a) deposition of oriented h-BN layer on Ni layer. (b) TEM image of multiple layers. (c) particulars of the layer stacking. (d) LEED image with electron beam energy of 74 eV. Copyright 2016, with permission of [90].

Figure 7

Left: AFM topography image of BNQDs. (b–f) HRTEM images of the BN dots. Right: PLE, PL and time-resolved PL spectra of BNQDs. (c–e) Energy states’ attribution to BNQDs luminescence. Copyright 2014, with permission of [92].

Figure 8

Hydrothermal synthesis route of BNQDs with boric acid and melamine. PL response of BNQDs measured by addition of different metal ions with a concentration of 200 µM at the excitation wavelength of 300 and 230 nm, respectively. Copyright 2017, with permission of ref. [98].

Figure 9

On the left: The UV-Vis absorption spectra and corresponding Gaussian fitting from (a) as prepared, (b) 100 °C, (c) 200 °C, and (d) 300 °C BONDs (in water, 0.1 mg mL⁻¹). On the right: 3D PL excitation-emission-intensity spectra of (a) BONDs, (b) 100 °C, (c) 200 °C, and (d) 300 °C (in water, 0.1 mg mL⁻¹). Copyright 2019, with permission of ref. [101].