Beryllene, the lightest Xene

After the discovery of sp²-hybridized graphene and even lighter borophene, the scientific quest for the thinnest metallic sheets prompts the discovery of beryllene. As beryllium lacks p-electrons, the hybridization and structural evolution of beryllene in determining electronic/excitonic behaviors are scientifically interesting. Herein, we report the experimental realization of freestanding flat beryllene sheets with a lateral dimension of ~0.2–4 μm via sonochemical exfoliation. High-resolution transmission electron microscopy establishes the existence of hexagonal, square and stripe crystallographic phases. While characteristic Raman fingerprints ~451 and ~614 cm⁻¹, and experimentally observed electrically metallic nature of beryllene (vindicated by density-functional-theory band structure calculations) establish beryllene synthesis. Room temperature magnetism in Be-G and Be-CNT hybrids (established by Raman mapping and magnetic force microscopic imaging) is an interesting finding. Beryllene was explored as a surface-enhanced Raman spectroscopy (SERS) anchor in molecular sensing, oxidation-resistant, and fire-resistant laminates. It is believed that the discovery of beryllene will lead to novel functionalities and emerging applications.