C568: A new two-dimensional sp2-sp3 hybridized allotrope of carbon

Using first-principles calculations, we designed a new two-dimensional sp(2)-sp(3) hybridized allotrope of carbon. This allotrope is made up of 5-6-8 carbon rings thus, known as C-568. C-568 is an indirect semi-conductor with a band gap of 1.13 eV (HSE06) at Gamma-M symmetric point in the Brillouin zone. The possibility of the existence of C-568 is evident from its energetic, dynamical, mechanical, and thermal stabilities. C-568 maintains its structural integrity up to 800 K, which we confirmed by employing ab-initio molecular dynamics (AIMD) simulations. C-568 shows extraordinary room temperature in-plane electronic mobility of order similar to 10(4) cm(2)V(-1)s(-1), which is significantly higher than the black phosphorus (similar to 10(3) cm(2)V(-1)s(-1)) monolayer. Energetically, this sheet is more stable than the other sp(2)-sp(3)-hybridized carbon allotropes such as pentagraphene and tetrahexcarbon. Moreover, C-568 can be stacked into three different configurations, which also exhibit interesting electronic as well as transport properties. These configurations are also dynamically stable and show in-plane mobilities of order similar to 10(4) cm(2)V(-1)s(-1). (C) 2019 Elsevier Ltd. All rights reserved.