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 °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.
In this work, we report on the exciton radiative lifetimes of graphitic carbon nitride monolayers in the triazine- (gC$_3$N$_4$-t) and heptazine-based (gC$_3$N$_4$-h) forms, as obtained by means of ground- plus excited-state ab initio calculations. By analysing the exciton fine structure, we highlight the presence of dark states and show that the photo-generated electron-hole pairs in gC$_3$N$_4$-h are remarkably long-lived, with an effective radiative lifetime of 260 ns. This fosters the employment of gC$_3$N$_4$-h in photocatalysis and makes it attractive for the emerging field of exciton de…
Atomically thin boron nitride (BN) nanosheets are important two-dimensional nanomaterials with many unique properties distinct from those of graphene, but the investigation of their mechanical properties still greatly lacks. 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 behaviors 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 …
Due to the noticeable structural similarity and being neighborhood in periodic table of group-IV and -V elemental monolayers, whether the combination of group-IV and -V elements could have stable nanosheet structures with optimistic properties has attracted great research interest. In this work, we performed first-principles simulations to investigate the elastic, vibrational and electronic properties of the carbon nitride (CN) nanosheet in the puckered honeycomb structure with covalent interlayer bonding. It has been demonstrated that the structural stability of CN nanosheet is essentially ma…
The compressive strain induced work function modulation in boron nitride nanosheets (BNNS) has been studied. The compressive strain arose due to the irradiation of 30 keV Au beam on thin films of BNNS. Before irradiation BNNS was characterized by Raman spectroscopy, UV-Vis spectroscopy, where using Tauc plot the bandgap of chemically synthesized BNNS from commercial hBN powder has been calculated as well as the layer numbers on thin films also quantified using an empirical relation exploiting the full width at half maxima (FWHM) of Raman peak of BNNS. The Scanning Electron Microscopy (SEM) ima…
The effect of doping of cubic boron nitride with beryllium, silicon, sulfur and magnesium on the lattice parameters, electrical conductivity and EPR spectra has been studied. It is established that the degree of doping increases significantly in the case of crystallization of cubic boron nitride from BN solutions in supercritical ammonia at 3.9-4.2 GPa and 1100°C in comparison with the conventional synthesis from melts of the Mg-B-N system at 4.2 GPa and 1400°C. Doping with silicon and beryllium results in semiconductor properties of cubic boron nitride.
Graphene nanoribbons are prepared inside boron nitride nanotubes by liquid phase encapsulation and subsequent annealing of 1,2,4-trichlorobenzene. The product is imaged with high resolution transmission electron microscopy, and characterized by optical absorption and Raman spectroscopy. Carbon-containing material is detected inside the boron nitride nanotubes with energy-dispersive x-ray spectroscopy (EDS) and scanning transmission electron microscopy (STEM). The observed structures twist under the electron beam and the characteristic features of nanoribbons appear in the Raman spectra.
In the wide world of 2D materials, hexagonal boron nitride (hBN) holds a special place due to its excellent characteristics. In addition to its thermal, chemical and mechanical stability, hBN demonstrates high thermal conductivity, low compressibility, and wide band gap around 6 eV, making it promising candidate for many groundbreaking applications and more specifically for optoelectronic devices. Millimeters scale hexagonal boron nitride crystals are obtained through a disruptive dual method (PDC/PCS) consisting in a complementary coupling of the Polymer Derived Ceramics route and a Pressure-…
Influence of Interface Geometry on Phase Stability and Bandgap Engineering in Boron Nitride substituted Graphene: A Combined First-principles and Monte Carlo Study
Length dependent lattice thermal conductivity of single \& multi layered hexagonal boron nitride: A first-principles study using the Callaway-Klemens \& real space super cell methods
Carbon nitride two-dimensional (2D) materials are among the most attractive class of nanomaterials, with wide range of application prospects. As a continuous progress, most recently, two novel carbon nitride 2D lattices of C3N5 and C3N4 have been successfully experimentally realized. Motivated by these latest accomplishments and also by taking into account the well-known C3N4 triazine-based graphitic carbon nitride structures, we predicted two novel C3N6 and C3N4 counterparts. We then conducted extensive density functional theory simulations to explore the thermal stability, mechanical, electr…
Stacking and Registry Effects in Layered Materials: The Case of Hexagonal Boron Nitride
采用van der Waals修正的密度泛函理论方法研究了六方氮化硼（h-BN）的层间滑移能谱.结果表明，范德华力的主要作用是将层间固定在一个固定的距离上，而静电力则决定了最佳的堆积模式和层间滑动能。一个几乎自由滑动的路径被确定，沿着该路径获得~0.6 eV的带隙调制。我们提出了一个简单的几何模型，量化层之间的注册表匹配，并捕捉波纹h-BN层间能量景观的本质。这种现象学模型的简单性为复杂的层状结构（如碳和氮化硼纳米管）的建模开辟了道路。
The current rechargeable battery technologies have a failure in their performance at high pressure and temperature. In this article, we have brought theoretical insights on using boron nitride flakes as a protecting layer for a lithium-ion battery device and extended its application for a spin-dependent photon emission device. Hence, the electronic properties of pristine and lithium-doped hydrogen-edged boron nitride flakes have been studied by the first principle density functional theory calculations. In this study, we have discussed the stability, adsorption energies, bond lengths, electron…
Spin defects in foils of hexagonal boron nitride are an attractive platform for magnetic field imaging, since the probe can be placed in close proximity to the target. However, as a III-V material the electron spin coherence is limited by the nuclear spin environment, with spin echo coherence time of $\sim100~\mathrm{ns}$ at room temperature accessible magnetic fields. We use a strong continuous microwave drive with a modulation in order to stabilize a Rabi oscillation, extending the coherence time up to $\sim4~\mathrm{μs}$, which is close to the 10-$\mathrm{μs}$ electron spin lifetime in our …
