Diamond-like 2D films based on a few layered graphenes: atomic and electronic structures, preparation methods and applications perspectives

Recently, graphene heterostructures have generated renovated interest for new findings on the induced chemical transformation of a few-layer thick epitaxial graphene into a new carbon all sp³ 2D films [1-3] earlier named diamanes [4] as fully hydrogenated (or fluorinated) bilayer graphene or a few layered graphene. In this work we provide a review of theoretical [4-7] and direct experimental works about these materials. We consider also new modeled structures such as Moire diamanes, based on bigraphenes with twistedangles near 30^o [8,9]. Using state-of-the-art computational techniques electronic, mechanical as well as energy stability were estimated and comparison with periodic approximant and AB-stacked diamanes was performed. New structure of quasicrystalline diamane demonstrates wide band gap of 3.4 – 4.5 eV and unique mechanical properties which makes it stiffer and more brittle than AB-stacked diamane. We proposed also the first two-dimensional carbon quasicrystal composed entirely of sp³ hybridized atoms – diamane quasicrystal, based on incommensurate twisted 30° bigraphene [10]. They could be fabricated through complete fluorination or hydrogenation of the bilayer graphene, similarly to synthesis of AB-stacked diamane by high pressure treatment. It was shown that their metal-doped analogues, which cover the spectrum of their conductive properties from semiconducting to metallic (with the possibility of conversion to a superconductor) [11]. These dielectric films are interesting due to their unique mechanical and optoelectronic, heat-transport and conductive (upon doping) properties [12-14]. It was proposed that such diamanes could be realized on the base of bilayer hexagonal boron nitride, silicene and other fabricated by functionalization of the bigraphenes by different adsorbents including chlorine, bromine [15]. We discuss the prospect of using such diamond-like structures of nanometer thickness in mechanical, optoelectronic and electronic nanodevices. The reported study was funded by RFBR, project number 20-02-00558. The calculations were performed using the resources provided by the Joint Supercomputer Center of the Russian Academy of Sciences.