Top view (top) and side view (bottom) of penta-graphane. Yellow and blue spheres show two types of carbon atoms, while red balls correspond to hydrogens.[1]
Penta-graphene is a hypotheticalcarbon allotrope composed entirely of carbon pentagons and resembling theCairo pentagonal tiling.[2] Penta-graphene was proposed in 2014 on the basis of analyses and simulations.[2] Further calculations predicted that it is unstable in its pure form,[3] but can be stabilized by hydrogenation.[1] Due to its atomic configuration, penta-graphene has an unusually negativePoisson’s ratio and very high ideal strength believed to exceed that of a similar material,graphene.[2]
Cairo pentagonal tiling
Penta-graphene contains bothsp2 andsp3 hybridized carbon atoms. Contrary to graphene, which is a good conductor of electricity, penta-graphene is predicted to be aninsulator with anindirect band gap of 4.1–4.3 eV. Its hydrogenated form is called penta-graphane. It has a diamond-like structure withsp3 and nosp2 bonds, and therefore a wider band gap (ca. 5.8 eV) than penta-graphene.[1] Chiral penta-graphene nanotubes have also been studied as metastable allotropes of carbon.[4][2][5]
Nazir, Muhammad Azhar; Hassan, Arzoo; Shen, Yiheng; Wang, Qian (2022). "Research progress on penta-graphene and its related materials: Properties and applications".Nano Today.44 101501.doi:10.1016/j.nantod.2022.101501.S2CID248767647.
