3,725 research outputs found
Boron Nitride Nanosheets for Metal Protection
Although the high impermeability of graphene makes it an excellent barrier to
inhibit metal oxidation and corrosion, graphene can form a galvanic cell with
the underlying metal that promotes corrosion of the metal in the long term.
Boron nitride (BN) nanosheets which have a similar impermeability could be a
better choice as protective barrier, because they are more thermally and
chemically stable than graphene and, more importantly, do not cause galvanic
corrosion due to their electrical insulation. In this study, the performance of
commercially available BN nanosheets grown by chemical vapor deposition as a
protective coating on metal has been investigated. The heating of the copper
foil covered with the BN nanosheet at 250 {\deg}C in air over 100 h results in
dramatically less oxidation than the bare copper foil heated for 2 h under the
same conditions. The electrochemical analyses reveal that the BN nanosheet
coating can increase open circuit potential and possibly reduce oxidation of
the underlying copper foil in sodium chloride solution. These results indicate
that BN nanosheets are a good candidate for oxidation and corrosion protection,
although conductive atomic force microscopy analyses show that the
effectiveness of the protection relies on the quality of BN nanosheets.Comment: With Supporting Informatio
Strong Oxidation Resistance of Atomically Thin Boron Nitride Nanosheets
Investigation on oxidation resistance of two-dimensional (2D) materials is
critical for many of their applications, because 2D materials could have higher
oxidation kinetics than their bulk counterparts due to predominant surface
atoms and structural distortions. In this study, the oxidation behavior of
high-quality boron nitride (BN) nanosheets of 1-4 layer thick has been examined
by heating in air. Atomic force microscopy and Raman spectroscopy analyses
reveal that monolayer BN nanosheets can sustain up to 850 {\deg}C and the
starting temperature of oxygen doping/oxidation of BN nanosheets only slightly
increases with the increase of nanosheet layer and depends on heating
conditions. Elongated etch lines are found on the oxidized monolayer BN
nanosheets, suggesting that the BN nanosheets are first cut along the
chemisorbed oxygen chains and then the oxidative etching grows perpendicularly
to these cut lines. The stronger oxidation resistance of BN nanosheets suggests
that they are more preferable for high-temperature applications than graphene
Dielectric Screening in Atomically Thin Boron Nitride Nanosheets
Two-dimensional (2D) hexagonal boron nitride (BN) nanosheets are excellent
dielectric substrate for graphene, molybdenum disulfide and many other 2D
nanomaterials based electronic and photonic devices. To optimize the
performance of these 2D devices, it is essential to understand the dielectric
screening properties of BN nanosheets as a function of the thickness. Here,
electric force microscopy along with theoretical calculations based on both
state-of-the-art first-principles calculations with van der Waals interactions
under consideration and non-linear Thomas-Fermi theory models are used to
investigate the dielectric screening in high-quality BN nanosheets of different
thicknesses. It is found that atomically thin BN nanosheets are less effective
in electric field screening, but the screening capability of BN shows a
relatively weak dependence on the layer thickness
Boron Nitride Nanosheets as Improved and Reusable Substrates for Gold Nanoparticles Enabled Surface Enhanced Raman Spectroscopy
Atomically thin boron nitride (BN) nanosheets have been found an excellent
substrate for noble metal particles enabled surface enhanced Raman spectroscopy
(SERS), thanks to their good adsorption of aromatic molecules, high thermal
stability and weak Raman scattering. Faceted gold (Au) nanoparticles have been
synthesized on BN nanosheets by a simple but controllable and reproducible
sputtering and annealing method. The size and density of the Au particles can
be controlled by sputtering time, current and annealing temperature etc. Under
the same sputtering and annealing conditions, the Au particles on BN of
different thicknesses show various sizes because the surface diffusion
coefficients of Au depends on the thickness of BN. Intriguingly, decorated with
similar morphology and distribution of Au particles, BN nanosheets exhibit
better Raman enhancements than silicon substrate as well as bulk BN crystals.
Additionally, BN nanosheets show no noticeable SERS signal and hence cause no
interference to the Raman signal of analyte. The Au/BN substrates can be reused
by heating in air to remove adsorbed analyte without loss of SERS enhancement.Comment: Complementary Info include
Mechanical properties of atomically thin boron nitride and the role of interlayer interactions
Atomically thin boron nitride (BN) nanosheets are important two-dimensional nanomaterials with many unique properties distinct from those of graphene, but investigation into their mechanical properties remains incomplete. Here we report that high-quality single-crystalline mono-and few-layer BN nanosheets are one of the strongest electrically insulating materials. More intriguingly, few-layer BN shows mechanical behaviours quite different from those of few-layer graphene under indentation. In striking contrast to graphene, whose strength decreases by more than 30% when the number of layers increases from 1 to 8, the mechanical strength of BN nanosheets is not sensitive to increasing thickness. We attribute this difference to the distinct interlayer interactions and hence sliding tendencies in these two materials under indentation. The significantly better interlayer integrity of BN nanosheets makes them a more attractive candidate than graphene for several applications, for example, as mechanical reinforcements
Boron Nitride Nanosheets Improve Sensitivity and Reusability of Surface Enhanced Raman Spectroscopy
Surface enhanced Raman spectroscopy (SERS) is a useful multidisciplinary
analytic technique. However, it is still a challenge to produce SERS substrates
that are highly sensitive, reproducible, stable, reusable, and scalable. Here,
we demonstrate that atomically thin boron nitride (BN) nanosheets have many
unique and desirable properties to help solve this challenge. The synergic
effect of the atomic thickness, high flexibility, stronger surface adsorption
capability, electrical insulation, impermeability, high thermal and chemical
stability of BN nanosheets can increase the Raman sensitivity by up to two
orders, and in the meantime attain long-term stability and extraordinary
reusability not achievable by other materials. These advances will greatly
facilitate the wider use of SERS in many fields
Atomically Thin Boron Nitride: Unique Properties and Applications
Atomically thin boron nitride (BN) is an important two-dimensional (2D)
nanomaterial, with many properties distinct from graphene. In this feature
article, these unique properties and associated applications often not possible
from graphene are outlined. The article starts with characterization and
identification of atomically thin BN. It is followed by demonstrating their
strong oxidation resistance at high temperatures and applications in protecting
metals from oxidation and corrosion. As flat insulators, BN nanosheets are
ideal dielectric substrates for surface enhanced Raman spectroscopy (SERS) and
electronic devices based on 2D heterostructures. The light emission of BN
nanosheets in the deep ultraviolet (DUV) and ultraviolet (UV) regions are also
included for its scientific and technological importance. The last part is
dedicated to synthesis, characterization, and optical properties of BN
nanoribbons, a special form of nanosheets
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