The discovery of bilayer borophene has highlighted the importance of interlayer covalent B−Bbonds in addressing the stability challenges of air-sensitive monolayerborophene, which showcases promising attributes for diverse electronic andenergy applications. Yet, investigations into multilayer borophene structures, particularly beyond the bilayer, are sparse. In this study, we conducted asystematic investigation of the geometries, stabilities, electronic structures,and work functions of 2- to 5-layer α7- and α8-borophene using density functional theory calculations, based on different stacking modes. Remarkably, we identified metallic 3- to 5-layer configurations of α7-borophene (α7ABA,α7ABAbB, and α7ABABA), each demonstrating the highest thermodynamic stability reported to date for their respective layer numbers. Additionally, the 3- to5-layer α8-borophene variants, including α8AAB, α8AABbA, and α8AABAB, also exhibited significant thermodynamic stability, ranking second highest among theborophene configurations examined. With increasing layer number from 2 to 5,the influence of in-plane orbitals (s, px, and py) on in plane bonding becamemore pronounced, while their effect on interlayer interactions diminished. This evolution led to greater geometric distortion within the layers and enhanced in-plane binding, resulting in higher overall binding energies in both the α7-and α8-borophene series. Importantly, the calculated work functions for the 3-to 5-layer α7- and α8-borophene were found to be comparable to that of graphene(4.37–4.60 eV), suggesting that these multilayer borophene materials could potentially serve as viable alternatives to graphene. Overall, these finding soffer valuable insights into the structural and electronic properties of multilayer borophene, paving the way for its integration into future nanotechnology applications.
The article discusses the advancements in borophene research, particularly the bilayer borophene, which has shown improved stability due tostrong B−B bonds between layers. This stability is crucial for practical applications, as the single-layer borophene is sensitive to air. The study goesbeyond the bilayer, exploring 2 to 5 layers of borophene, specifically the α7 and α8 types. Using density functional theory calculations, the researchers analyzed the shapes, stability, electronic structures, and work functions (the energy needed to remove an electron from a solid) of these multilayer structures. They discovered that 3 to 5 layers of α7 borophene have the highest stability ever reported for such structures. The α8 borophene also showed significantstability, especially in its 3 to 5 layer configurations. As more layers are added, the bonding within the layers becomes stronger due to the influence of in-plane orbitals (s, px, and py), while the interactions between layers become less significant. This leads to a distortion in the layers’ geometry but results in stronger bonds within the plane, increasing the overall energy needed to break these bonds. Interestingly, the work functions for these multilayer borophene structures are similar to graphene (rangingfrom 4.37 to 4.60 eV), suggesting that multilayer borophene could be a good alternative to graphene in various applications. In summary, this research provides valuable information on the properties of multilayer borophene, which could be very useful for future developments in nanotechnology.
