Supporting Information for Advanced Materials, adma.0070066 Wiley-VCH 007 69451 Weinheim, Germany
High-Yield Synthesis of Rhombohedral BN Triangular Nanoplates Liqiang Xu, Jinhua Zhan*, Junqing Hu, Yoshio Bando, Xiaoli Yuan, Takashi Sekiguchi Masanori Mitome, and Dmitri Golberg Supporting information Table of Contents SI-1 SEM images of rhombohedral BN triangular nanoplates a) An overview SEM image; b) High-resolution SEM image showing the stacking of nanoplates; c) High-resolution SEM image showing the thickness of nanoplates; d) BN particle size distribution obtained by Zetasizer 000 particle size laser analyzer; e) Simulation of a triangular nanoplate viewed along various tilt angles. SI- Elemental maps collected from an individual r-bn nanoplate reveal that B and N atoms are homogeneously distributed in the nanostructures. SI- TEM image and electron diffraction pattern of flake-like BN particles generated in the absence of the metals. SI-4 TEM image and electron diffraction pattern of rhombohedral BN triangular nanoplates generated in the presence of metallic Ni. SI-5 a) Selected-area electron diffraction (SAED) patterns taken from an individual triangular nanoplate tilted inside the TEM suggesting its rhombohedral BN crystal structure; b) High-resolution TEM image taken from an individual triangular nanoplate along the [ 111] direction showing its one corner; c) SEM images taken from nickel sponge showing its surface. SI-6 a) -layer-stacking structural model of Ni (111); b) Configuration for one-monolayer BN/Ni (111). c) one possible configuration of a bended BN triangular monolayer. SI-7 a) The UV-Visible absorption spectrum of r-bn triangular nanoplates; b) plot of ( E photo ) vs. E photo; c) High-resolution CL spectrum taken from r-bn nanoplates at 14 K; d) Band-gap energy for III-V nitride semiconductors. SI-8 Formation process of rhombohedral BN triangular nanoplate. 1
SI-1 SEM images of rhombohedral BN triangular nanoplates and simulation of a triangular nanoplate viewed along various tilt angles a) An overview SEM image of as-obtained r-bn triangular nanoplates; b) High-resolution SEM image showing the stacking of r-bn triangular nanoplates on each other; 80 Size distribution(s) % in class 60 40 0 c) High-resolution SEM image showing the thickness of r-bn triangular nanoplates; 5 10 50 100 500 1000 Diameter (nm) d) BN particle size distribution obtained by Zetasizer 000 particle size laser analyzer. The larger particles possibly originate from the agglomeration of nanoplates in ethanol solution; [001] Tilt angle: 0 6.91 56.5 66.07 77.49 90 e) simulation of a triangular nanoplate viewed along various tilt angles.
SI- Elemental maps collected from an individual r-bn nanoplate reveal that B and N atoms are homogeneously distributed in the nanostructures. SI- TEM image and electron diffraction pattern of flake-like BN particles generated in the absence of metallic powder intensity (a.u.) 10 004 101 110 11 00 0 4 6 8 10 q/nm -1 a) TEM image, inset is the ED pattern; b) electron-diffraction profile giving d-spacings consistent with h-bn (JCPDS card 45-0895). SI-4 TEM images and electron diffraction pattern of rhombohedral BN triangular nanoplates generated in the presence of metallic Ni sponge. intensity (a.u.) 10 110 11 01 0 101 0 4 6 8 10 q/nm -1 a) TEM image, inset is the ED pattern; b) electron-diffraction profile giving d-spacings consistent with r-bn (JCPDS card 45-1171).
SI-5 a) b) c) SI-5 a) Selected-area electron diffraction (SAED) patterns taken from an individual triangular nanoplate with different tilting angles inside the TEM, suggesting its rhombohedral BN crystal structure. The angles between [ 011 ], [ 111 ] and [ 001 ] are 14 and.45, respectively; b) High-resolution TEM image taken from an individual triangular nanoplate along the [ 111] direction showing its one corner, the top-left inset is its corresponding Fourier-transform pattern. This HRTEM image is consistent with the projection of the r-bn crystal along the [ 111] direction, as shown in its top middle inset; c) SEM image and high-resolution SEM image showing the surfaces of nickel sponge. 4
SI-6 a) fcc hollow site b) hcp hollow site.49å H B N Ni c) SI-6 a) A -layer-stacking structural model of Ni (111). Its fcc hollow site and hcp hollow site are marked with black and yellow arrows, respectively; b) Configuration for one-monolayer BN/Ni (111). The terminated N atoms are saturated with H atoms. The interatomic distance of two adjacent Ni atoms is.49å, whereas that of two adjacent N atoms in one BN monolayer is.50å. The similar lattice parameter allows a perfect epitaxial growth of BN on Ni (111). N atoms sit on the top sites of the Ni atoms; c) one possible configuration of a bended BN triangular monolayer whose edges are terminated with H-saturated N atoms. 5
SI-7 a) b) absorbance (a.u.) ( E photo ) c) 00 00 400 500 600 700 800 wavelength/nm CL intensity (a.u.) 00 0 40 60 Wavelength/nm d) SI-7 a) The UV-Visible absorption spectrum of r-bn triangular nanoplates dispersed in ethanol solution; b) plot of ( E photo ) vs. E photo. An estimated optical band gap is obtained using the following equation for a semiconductor: h = A (h -E g ) m/, where A is a constant, is the absorption coefficient, E g is the band gap and m equals 1 for a direct transition. The intercept of a plot of ( E photo ) vs. E photo on the energy axis gives E g for a direct transition; c) High-resolution CL spectrum taken from r-bn nanoplates at 14 K; d) Band-gap energy for III-V nitride semiconductors, ZB = Zinc-blende, W= Wurtzite, H = Hexagonal. E g /ev 1 4 5 6 Energy/eV 9 8 7 6 5 4 ZB W H-BN BN AlN GaN InN 6
SI-8 Formation process of rhombohedral BN triangular nanoplates During the formation process of r-bn triangular nanoplates, the involved thermodynamic chemical reactions may possibly proceed as follows: NH NaNH 4 BF BF NH HF( g) Na 4 HF( g) NaNH NH HF( g) BF, Ni BN ( s) HF( g) N ( s) NaF ( s) NH Na N ( s) NH ( s) NaF ( s) NH NH 4BF4 4NaNH 4NaF ( s) BN ( s) 4NH At a temperature around 600, NH 4 BF 4 and NaNH may spontaneously decompose to produce BF and NH vapors (reaction 1 and ), respectively. 1, The reaction between BF (g) and NH (g) (reaction ) over the surface of metallic Ni powder generate regular sp -hybridzed BN triangular monolayers. BN crystal was also generated via means of a traditional chemical vapor deposition (CVD) from a BF /NH mixture system., 4 A scheme showing this assistant role is depicted in SI-6. Further reactions will drive the crystal growth of rhombohedral BN over these basal BN planes. The HF (g) produced by the reaction 1 and can instantly be consumed by Na N and NaNH to form NaF and NH, as described by the reaction 4 and 5, respectively. A total reaction between NH 4 BF 4 and NaNH can be described as the reaction 6. SI-References: [1] D. Göbbels; G. Z. Meyer, Anorg. Allg. Chem. 00, 68, 1799. [] a) H. Y. Leng, T. Ichikawa, S. Hino, N. Hanada, S. Isobe, H. Fujii, J. Power Sources 006, 156, 166; b) K. Jones, In Comprehensive Inorganic Chemistry (Ed.: A. F. Trotman-Dickinson), Pergamon Press, Oxford, 197, Vol., p147; (c) Advanced Inorganic Chemistry (Eds: F. A. Cotton, G. Wilkison) Interscience Publishers, London, 1966, p1. [] S. Prouhet, F. Langlais, A. Guette, R. Naslain, J. Rey, Euro. J. Solid State Inorg. Chem. 199, 0, 95. [4] A. G. Avent, P. B. Hitchcock, M. F. Lappert, D. S. Liu, G. Mignani, C. Richard, E. Roche, J. Chem. Soc., Chem. Commun., 1995, 855. (1) () () (4) (5) (6) 7