Synthesis of Atomically Thin Hexagonal Diamond with Compression

Abstract

Atomically thin diamond, also called diamane, is a twodimensional carbon allotrope and has attracted considerable scientific interest because of its potential physical properties. However, the successful synthesis of a pristine diamane has up until now not been achieved. We demonstrate the realization of a pristine diamane through diamondization of mechanically exfoliated few-layer graphene via compression. Resistance, optical absorption, and X-ray diffraction measurements reveal that hexagonal diamane (h-diamane) with a bandgap of 2.8 ± 0.3 eV forms by compressing trilayer and thicker graphene to above 20 GPa at room temperature and can be preserved upon decompression to ∼1.0 GPa. Theoretical calculations indicate that a (−2110)-oriented h-diamane is energetically stable and has a lower enthalpy than its few-layer graphene precursor above the transition pressure. Compared to gapless graphene, semiconducting h-diamane offers exciting possibilities for carbon-based electronic devices.

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

“…High-pressure experiments with bi-and multilayered graphanes show the formation of 2D diamond structures [56,57]. These kinds of diamanes without adsorbents on the surfaces, named diamondenes [56], could serve as diamond seeds in nanoheterostructures and rocks subjected to high pressures.…”

Diamane: design, synthesis, properties, and challenges

“…Unfortunately, the graphene structure maintained after the pressure was released. Recently, the phase transition pressure of pristine graphene was estimated by the measurement of resistance [25]. Sheet resistance of samples with different layers as a function of pressure is shown in Figure 7.…”

“…In the past decades, numerous investigations on the properties of diamane were performed and its potential applications were found in the fields of nano-photonics [21,22] and ultrasensitive resonator-based sensors [23]. Recently, it is exciting that the fully fluorinated AB-stacked diamane [24] and pristine diamane with (2 -110) orientation [25] were synthesized successfully in experiments. It should be noted that in previous literatures, different names, such as diamane [20,[24][25][26], diamondol [27], diamondene [28], or diamene [29], was adopted for diamane, due to the diversity of surface functional groups on the diamond film surface.…”

“…Recently, it is exciting that the fully fluorinated AB-stacked diamane [24] and pristine diamane with (2 -110) orientation [25] were synthesized successfully in experiments. It should be noted that in previous literatures, different names, such as diamane [20,[24][25][26], diamondol [27], diamondene [28], or diamene [29], was adopted for diamane, due to the diversity of surface functional groups on the diamond film surface. Here, for the convenience of discussion, we call them collectively as diamane.…”

“…the inset is pressure dependence of the resistance of graphite. Reprinted from[25]. copyright 2020 american chemical Society.…”