By Professor Yoke Khin Yap
The arrangement of carbon atoms differentiates a pencil lead from a pricey diamond. In the past three decades, new carbon materials such as fullerenes1, carbon nanotubes (CNTs)2, and graphene3 have attracted tremendous research interest and led to two Nobel Prizes4,5. More recently, graphene nanoribbons (GNRs)6,7 have gained increasing attention from the research community.
Materials in the boron nitride (BN) system are structurally similar to the carbon solids. We have hexagonal phase-BN (h-BN), cubic phase-BN (c-BN), BN nanotubes (BNNTs), BN nanosheets, BN nanoribbons (BNNRs), which are analogous to graphite, diamonds, CNTs, graphene, and GNRs respectively8-11.
For comparison purpose, the atomic structures of a CNT and a BNNT, as well as a GNR and a BN nanoribbon are shown in Figure 1. In fact, there are significant advancement on BN nanomaterials in the past few years11-14, including low temperature growth15,16, patterned growth15,17-19, discovery of superhydrophopicity of BNNTs20, and successful growth of BN sheets21.
Figure 1. Zigzag (10, 0) (a) CNT and (b) BNNT and Zigzag GNR and BN Nanoribbon. Grey, red, and green spheres represent carbon, boron, and nitrogen atoms, respectively.
Direct growth of BNNRs was also reported in 2007 and was referred as BN nanowires22 until recently23. Some of these advancements are highlighted in Figure 2. These BN materials have properties different from the carbon counterparts. For instance, graphite is a conductor while h-BN is an insulator. Apparently, BN materials will complement the uses of carbon solids in various areas of advanced science and technology.
Figure 2. (a) Schematic of thermal chemical vapor deposition (CVD) for the growth of BNNTs. (b) SEM images of the as grown BNNTs and the spectra of electron energy loss spectroscopy (EELS). (c) SEM images of BNNTs grown at desired patterns by catalytic CVD (CCVD). (d) TEM images of the BNNTs. (e) Absorption spectra showing a band gap ~6eV without sub-band absorption levels (1: high-quality BNNTs by CCVD, 2: BNNTs grown by thermal CVD, 3: ethanol). (f) Water droplets on BNNT films showing superhydrophopic behavior of vertically-aligned BNNTs.
The merge of carbon and BN systems forms the so called B-C-N materials. Nanomaterials within this B-C-N triangular zone offer new vistas for materials research. They include clusters, nanotubes, nanosheets, nanoribbons, and new nanostructures of carbon, boron, boron nitride, carbon nitride, boron carbide, and boron carbon-nitride. These materials are sometime called 'frontier carbon materials' because of their flexibility to form various covalent bonds like those in pure carbon solids24. Figure 3 summarizes the possible nanomaterials within the B-C-N triangular zone.
Figure 3. Nanomaterials within the B-C-N triangular zone.
Details of these topics are discussed in a recent book25. Clearly, the ability to control bond hybridization, molecular packing, and composition of these materials is important to create new materials with novel properties24. They could possibly be useful for protective coatings, high-power electronics, nano-electronic and nanoscale sensing devices, which are indispensable materials for the advancement of science in the 21st century.
Y. K. Yap acknowledges supports from National Science Foundation CAREER Award (Award number 0447555, Division of Materials Research), and the U. S. Department of Energy, the Office of Basic Energy Sciences (Grant No. DE-FG02-06ER46294, Division of Materials Sciences and Engineering).
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- M. Y. Han, B. Ozyilmaz, Y. B. Zhang, and P. Kim, "Energy Band-Gap Engineering of Graphene Nanoribbons," Phys. Rev. Lett. 98, 206805 (2007).
- Y. K. Yap, "Boron-Carbon Nitride Nanohybrids," in Encyclopedia of Nanoscience and Nanotechnology (Foreword by R. E. Smalley), Volume 1, H. S. Nalwa (Ed.), American Scientific Publishers (www.aspbs.com/enn) (2004) pp. 383-394.
- C. H. Lee, and Y. K. Yap, "Current Research Status of Boron-Carbon Nitride Bulks, Thin Films, and Nanostructures," in Chapter 10 of Diamond and Related Materials Research (Nova Science Publisher, 2008) pp 277-292. (https://www.novapublishers.com/catalog/product_info.php?products_id=6641)
- C. H. Lee, V. K. Kayastha, J. Wang, and Y. K. Yap, "Introduction to B-C-N Materials," in Chapter 1 of B-C-N Nanotubes and Related Nanostructures, Lecture Notes in Nanoscale Science and Technology (Springer), Vol. 6, Yoke Khin Yap (Ed.) (2009) pp 1-22.
- J. Wang, M. Xie, and Y. K. Yap, "Boron Nitride Nanotubes: Low-Temperature Growth and Characterization," in Encyclopedia of Nanoscience and Nanotechnology Volume 12, H. S. Nalwa (Ed.), American Scientific Publishers (www.aspbs.com) (2010) pp 97-107.
- J. Wang, C. H. Lee, Y. Bando, D. Golberg, and Y. K. Yap, "Multiwalled Boron Nitride Nanotubes: Growth, Properties, and applications," in Chapter 2 of B-C-N Nanotubes and Related Nanostructures, Lecture Notes in Nanoscale Science and Technology (Springer), Vol. 6, Yoke Khin Yap (Ed.) (2009) pp 23-44.
- J. Wang, C. H. Lee and Y. K. Yap, "Recent advancements in boron nitride nanotubes," Nanoscale 2, 2028 (2010).
- D. Golberg, Y. Bando, Y. Huang, T. Terao, M. Mitome, C. Tang and C. Zhi, "Boron Nitride nanotubes and Nanosheets," ACS Nano 4, 2979 (2010).
- J. Wang, V. Kayastha, Y. K. Yap, Z. Fan, J. G. Lu, Z. Pan, I. Ivanov, A. A. Purezky, D. B. Geohegan, "Low temperature growth of boron nitride nanotubes on substrates," Nano Lett. 5, 2528 (2005).
- C. H. Lee, J. Wang, V. K. Kayastha, J. Y. Huang, and Y. K. Yap, "Effective growth of boron nitride nanotubes by thermal chemical vapor deposition," Nanotechnology 19, 455605 (2008).
- C. H. Lee, M. Xie, V. Kayastha, J. Wang and Y. K. Yap, "Patterned Growth of Boron Nitride Nanotubes by Catalytic Chemical Vapor Deposition," Chem. Mater. 22, 1782 (2010).
- C. Sealy, "Boron Nitride Nanotubes Grown Just Like Carbon Nanotubes," Nano Today 5, 80 (2010). http://www.phy.mtu.edu/yap/documents/NanoTodayBNNTs.pdf
- M. Goodrich, " Yap: Harnessing the Divas of the Nanoworld," http://www.eurekalert.org/pub_releases/2010-01/mtu-htd011510.php?loc=interstitialskip
- C. H. Lee, J. Drelich, and Y. K. Yap, "Superhydrophobicity of Boron Nitride Nanotubes Grown on Silicon Substrates," Langmuir (letter) 25, 4853 (2009).
- L. Song, L. Ci, H. Lu, P. B. Sorokin, C. Jin, J. Ni, A. G. Kvashnin, D. G. Kvashnin, J. Lou, B. I. Yakobson and P. M. Ajayan, "Large Scale Growth and Characterization of Atomic Hexagonal Boron Nitride Layers," Nano Lett. 10, 3209 (2010).
- Y. K. Yap, "Synthesis, Characterization and Discovery of Frontier Carbon Materials," in Solid State and Materials Chemistry Highlights FY 2007, NSF. http://www.nsf.gov/mps/dmr/highlights/07highlights/ssmc.jsp
- J. Wang, C. H. Lee, V. K. Kayastha and Y. K. Yap, "First Success in the Synthesis of Boron Nitride Nanotubes and Hetero-junctions of Boron Nitride Nanotubes and Carbon Nanotubes, in Symposium K: Nanotubes and Related Nanostructures, 2009 Materials Research Society Fall Meeting, Nov. 30-Dec 4, in Boston, Paper K17.6. http://www.mrs.org/s_mrs/doc.asp?CID=24490&DID=263661
- Y. K. Yap (Editor), B-C-N Nanotubes and Related Nanostructures, Lecture Notes in Nanoscale Science and Technology (Springer), Vol. 6, (2009). http://www.springer.com/materials/nanotechnology/book/978-1-4419-0085-2
- Y. K. Yap, National Science Foundation Award # 0447555, "CAREER: Synthesis, Characterization and Discovery of Frontier Carbon Materials. http://www.nsf.gov/awardsearch/showAward.do?AwardNumber=0447555
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