Fully Hydrogenated and Fluorinated Bigraphenes–Diamanes: Theoretical and Experimental Studies

Abstract

Diamanes are 2D diamond-like films that are nanometers in thickness. Diamanes can exist as bilayer or multilayer graphene with various modes of stacking and interlayer covalent sp3 bonds. The term “diamane” is used broadly for a variety of diamond-like materials at the nanoscale, from individual diamond clusters to nanocrystal films. A short overview of recent progress in the investigation of diamanes, starting from the first theoretical predictions to practical realization, is presented. The results of both theoretical and experimental studies on diamanes with various atomic structures and types of functionalization are considered. It is shown that diamanes are stronger than graphene and graphane and have wide bandgaps ranging from 3.1 to 4.5 eV depending on the structure. Diamane-like structures have been obtained using different experimental techniques, and their structures have been determined by Raman spectroscopy. The potential applications of these carbon nanostructures are briefly reviewed.

Progress in Diamanes and Diamanoids Nanosystems for Emerging Technologies

“…[35,52,53] In addition to the functional groups, pressure can also be applied as an alternative for the formation of diamanes, but maintaining stability at low pressure is challenging. Pressure application for the formation of diamane is normally discouraged due to the [50] Copyright 2021, TheAuthors. Published by MDPI.…”

“…[36,51] Moreover, when pressure is used in the synthesis, inhibition of graphene is reversible but this property is absent in single-layered graphene. [50]…”

“…[48] After the increase in layers, the direct bandgap is converted to an indirect bandgap, which greatly influences the electron carrier mobility and quantum tunneling. [50] Recent theoretical updates indicate that the nature of surface manipulation and film thickness, both influence the location of the valence band at the top of the graphene layer and the conduction band at the bottom of the graphene layer. [34,59,66] This specific change could be utilized to incorporate desired semiconducting properties into diamane.…”

“…These changes in electronic structure influence the electronic spectra, frequency shifts, presence of active phonon modes, and quantum peculiarities of hydrogenated diamanes. [50,70,78] During the functionalization or substitution, not only the band gap is altered, but the superconductivity, insulation, and other important electronic properties are also affected. The interlayer interaction of bilayered graphene provides the characteristics of superconductivity in its magicangle of 1.1˚.…”

Ultra-Thin Carbon Films: The Rise of sp3-C-Based 2D Materials?

“…It includes a contribution from the group that pioneered the research on these new materials by being the first to hypothesize them [16,17]. Chernozatonskii and coworkers provide a review on theoretical and experimental studies on diamane-related materials with various atomic structures and types of functionalization (with either hydrogen or fluor) [18]. This article includes recent results on diamane systems exhibiting Moirés, i.e., involving domains with slight rotational misorientations.…”