Ranjan Pranay, Lee Jang Mee, Kumar Prashant, Vinu Ajayan
Department of Physics, Indian Institute of Technology Patna, Bihta, Patna, Bihar, 801103, India.
Department of Physics, UAE University, Al-Ain, Abu Dhabi, 15551, United Arab Emirates.
Adv Mater. 2020 Aug;32(34):e2000531. doi: 10.1002/adma.202000531. Epub 2020 Jul 14.
Borophene, a 2D allotrope of boron and the lightest elemental Dirac material, is the latest very promising 2D material owing to its unique structural and electronic characteristics of the X and β phases. The high atomic density on ridgelines of the β phase of borophene provides a substantial orbital overlap, which leads to an excellent electron density in the conduction level and thus to a highly metallic behavior. These unique structural characteristics and electronic properties of borophene attract significant scientific interest. Herein, approaches for crystal growth/synthesis of these unique nanostructures and their potential technological applications are discussed. Various substrate-supported ultrahigh-vacuum growth techniques for borophene, such as molecular beam epitaxy, atomic layer deposition, and chemical vapor deposition, along with their challenges, are also summarized. The sonochemical exfoliation and modified Hummer's technique for the synthesis of free-standing borophene are also discussed. Solution-phase exfoliation seems to address the scalability issues and expands the applications of these unique materials to various fields, including renewable energy devices and ultrafast sensors. Furthermore, the electronic, optical, thermal, and elastic properties of borophene are thoroughly discussed and are compared with those of graphene and its "cousins." Numerous frontline applications are envisaged and an outlook is presented.
硼烯是硼的一种二维同素异形体，也是最轻的元素狄拉克材料，由于其X相和β相独特的结构和电子特性，它是最新出现的非常有前景的二维材料。硼烯β相脊线上的高原子密度提供了大量的轨道重叠，这导致导带中的电子密度极佳，从而呈现出高度的金属行为。硼烯这些独特的结构特性和电子性质引起了科学界的极大兴趣。本文讨论了这些独特纳米结构的晶体生长/合成方法及其潜在的技术应用。还总结了用于硼烯的各种衬底支撑的超高真空生长技术，如分子束外延、原子层沉积和化学气相沉积，以及它们所面临的挑战。还讨论了用于合成独立硼烯的声化学剥离法和改进的Hummer法。溶液相剥离似乎解决了可扩展性问题，并将这些独特材料的应用扩展到包括可再生能源器件和超快传感器在内的各个领域。此外，还对硼烯的电子、光学、热学和弹性性质进行了深入讨论，并与石墨烯及其“同类物”的性质进行了比较。设想了众多前沿应用并给出了展望。
