Theoretical dissection of superconductivity in two-dimensional honeycomb borophene oxide B2O crystal with a high stability

Abstract

Atomically thin borophene has recently been synthesized experimentally, significantly enriching the boron chemistry and broadening the family of two-dimensional (2D) materials. Recently, oxides of 2D materials have been widely investigated for next-generation electronic devices. Based on the first-principles calculations, we predict the existence of the superconductivity in honeycomb borophene oxide (B2O), which possesses a high stability and could be potentially prepared by intrinsically incorporating oxygen into the recently synthesized borophene. The mechanical, electronic, phonon properties, as well as electron–phonon coupling of metallic B2O monolayer, have been systematically scrutinized. Within the framework of the Bardeen–Cooper–Schrieffer theory framework, the B2O monolayer exhibits an intrinsic superconducting feature with a superconducting transition temperature (Tc) of ~10.3 K, higher than many 2D borides (0.2–7.8 K). Further, strain can be utilized to tune the superconductivity with the optimal Tc of 14.7 K under a tensile strain of 1%. The superconducting trait mainly originates from the out-of-plane soft-mode vibrations of the system, which are significantly enhanced via the light O atoms’ incorporation compared to other 2D metal-boride superconductors. This strategy would open a door to design 2D superconducting structures via the participation of light elements. We believe our findings greatly bloom the 2D superconducting family and pave the way for future nanoelectronics.

Borophene via Micromechanical Exfoliation

“…To resolve this, we intentionally oxidized transferred borophene and analyzed it (see Figure 5a S12 in the Supporting Information). [34,35] Distinguishable Raman signatures of both borophene and borophene oxide are shown (see Figure 5b,c, respectively). FTIR stretches corresponding to oxygen functionalities (epoxy and other oxide forms) were observed for the borophene oxide sample obtained via thermal oxidation (see Figure 5d).…”

Reversible Hydrogen Storage in Metal-Decorated Honeycomb Borophene Oxide

“…These results agree well with other DFT results from the literature. 32 , 33 A single H 2 molecule is then added to the system to compute the binding to the 2D B 2 O structure. According to eq 1 , a single H 2 adsorbs with a binding energy of −0.10 eV/H 2 to the 2D B 2 O structure.…”

“…Similar to other 2D boron-based structures, such as borophene, 36 2D boron oxides can form different structural polymorphs. 33 , 34 , 37 Honeycomb B 2 O has lower formation energy compared to other 2D allotropes such as B 4 O, B 5 O, B 6 O, B 7 O, and B 8 O indicating its stability. 32 , 33 Other 2D polymorphs of boron oxide such as the recently reported B 2 O 3 37 may also be suitable for H 2 storage applications, however, the study of these materials is beyond the scope of this work.…”

“… 31 Although uncontrolled oxidation is undesirable, one can intentionally use the oxidation process to produce structures that are more chemically stable. 32 , 33 For this reason, researchers have been actively looking into a variety of 2D boron oxide structures. 33 , 34 Inspired by the recent synthesis of honeycomb borophene on an Al substrate, 21 , 32 a 2D honeycomb borophene oxide (B 2 O) structure has been theoretically proposed.…”

“… 32 , 33 For this reason, researchers have been actively looking into a variety of 2D boron oxide structures. 33 , 34 Inspired by the recent synthesis of honeycomb borophene on an Al substrate, 21 , 32 a 2D honeycomb borophene oxide (B 2 O) structure has been theoretically proposed. 32 Phonon dispersion and ab initio molecular dynamics simulations have shown that the 2D honeycomb B 2 O structure is stable at temperatures up to 1000 K. 32 2D honeycomb B 2 O has a high capacity for Li/Na functionalization, thereby being a promising anodic material.…”