Proton Migration on the Boron Sheets Surface

Borophene is a two-dimensional allotrope of boron and it is also known as boron sheet. First it has been predicted theoretically in the mid-1990s, experimentally borophene was confirmed in 2015 when the structure was successfully synthesized in 2015. One of the key features of borophene is its strong anisotropy – the dependence of mechanical and electrical properties on direction. This phenomenon is not typical for 2D materials and has never been observed in 2D metals before. Borophene has the highest tensile strength of all known two-dimensional materials. In early works, it was found that the adsorption of a hydrogen atom on the surface of borophene is possible and the analyses of electronic density showed that atom H became a proton. Therefore, in this work, the authors have studied the proton migration over the surface of boron sheets of two types and have found the most energetically favorable path of proton motion. The electron-energy characteristics of the process of migration of a single proton along the surface of boron layers of two types are determined and it is established that in all the considered cases the proton is able to move along the surface almost barrier-free. The type of conductivity of pure boron layers and layers modified by a single proton is determined. In the A-type boron layer, the proton increases the band gap by 0.04 eV, and in the B-type layer, the band gap changes by 0.05 eV. It is proved that two-dimensional boron nanostructures can be considered as a new class of boron topological structure with proton conductivity.

Hypersonic impact properties of pristine and hybrid single and multi-layer C3N and BC3 nanosheets

Carbon, nitrogen, and boron nanostructures are promising ballistic protection materials due to their low density and excellent mechanical properties. In this study, the ballistic properties of C3N and BC3 nanosheets against hypersonic bullets with Mach numbers greater than 6 were studied. The critical perforation conditions, and thus, the intrinsic impact strength of these 2D materials were determined by simulating ballistic curves of C3N and BC3 monolayers. Furthermore, the energy absorption scaling law with different numbers of layers and interlayer spacing was investigated, for homogeneous or hybrid configurations (alternated stacking of C3N and the BC3). Besides, we created a hybrid sheet using van der Waals bonds between two adjacent sheets based on the hypervelocity impacts of fullerene (C60) molecules utilizing molecular dynamics simulation. As a result, since the higher bond energy between N–C compared to B-C, it was shown that C3N nanosheets have higher absorption energy than BC3. In contrast, in lower impact speeds and before penetration, single-layer sheets exhibited almost similar behavior. Our findings also reveal that in hybrid structures, the C3N layers will improve the ballistic properties of BC3. The energy absorption values with a variable number of layers and variable interlayer distance (X = 3.4 Å and 4X = 13.6 Å) are investigated, for homogeneous or hybrid configurations. These results provide a fundamental understanding of ultra-light multilayered armors' design using nanocomposites based on advanced 2D materials. The results can also be used to select and make 2D membranes and allotropes for DNA sequencing and filtration.

Hypersonic Impact Properties of Pristine and Hybrid Single and Multi-layer C3N and BC3 Nanosheets

Two-dimensional (2D) materials are competitive candidates replacing or supplementing conventional semiconductors due to their atomically uniform thickness. To observe and exploit the unique properties of two-dimensional (2D) materials, it is therefore vital to obtain clean and repeatable interfaces. Also, carbon, nitrogen, and boron nanostructures are promising ballistic protection materials due to their low density and excellent mechanical properties. In this study, we evaluated the ballistic properties of C3N and BC3 nanosheets against the hypersonic bullets with Mach number greater than 6. Besides, we created a hybrid sheet using van der Waals bonds between them based on the hypervelocity impacts of fullerene (C60) molecules utilizing molecular dynamics simulation. In the following, the ballistic properties of different structures were examined, and it was shown that C3N nanosheets have higher absorption energy than BC3 after C60 penetration. In contrast, in lower impact speeds and before penetration, single-layers exhibited almost similar behavior. Our findings also reveal that in hybrid structures, the C3N layers will improve the ballistic properties of BC3. The energy absorption values with a variable number of layers and interlayer distance are investigated, for homogeneous or hybrid configurations (stacking of C3N and BC3). In this work, we have discussed two interlayer distances of X = 3.4Å and 4X = 13.6Å for different configurations. These results provide a fundamental understanding of ultra-light multilayered armors' design using nanocomposites based on advanced 2D materials. It can also be used to select and make 2D membranes and allotropes for DNA sequencing and filtration.

Boron nanostructures obtained via ultrasonic irradiation for high performance chemiresistive methane sensors

Boron nanostructures obtained via a top-down approach can be efficiently used as the receptor in chemiresistive methane gas sensors.