Progress on Diamane and Diamanoid Thin Film Pressureless Synthesis

Fabrice Piazza 1,* , Marc Monthioux 2 , Pascal Puech 2, Iann C. Gerber 3 and Kathleen Gough 4

1 Laboratorio de Nanociencia, Pontificia Universidad Católica Madre y Maestra, Santiago, Apartado Postal 822, Dominican Republic
2 Centre d’Elaboration des Matériaux et d’Etudes Structurales (CEMES), CNRS, Université de Toulouse,
BP 94347, Toulouse CEDEX 4, 31055 Toulouse, France; marc.monthioux@cemes.fr (M.M.); pascal.puech@cemes.fr (P.P.)
3 Laboratoire de Physico-Chimie des Nano-Objets (LPCNO), CNRS, INSA, Université de Toulouse, 31400 Toulouse, France; igerber@insa-toulouse.fr
4 Department of Chemistry, University of Manitoba, Winnipeg, MB R3T 2N2, Canada; Kathleen.Gough@umanitoba.ca
* Correspondence: fpiazza@pucmm.edu.do

ABSTRACT: Nanometer-thick and crystalline sp3-bonded carbon sheets are promising new wide bandgap semiconducting materials for electronics, photonics, and medical devices. Diamane was prepared from the exposure of bi-layer graphene to hydrogen radicals produced by the hot-filament process at low pressure and temperature. A sharp sp3-bonded carbon stretching mode was observed in ultraviolet Raman spectra at around 1344–1367 cm􀀀1 while no sp2-bonded carbon peak was simultaneously detected. By replacing bi-layer graphene with few-layer graphene, diamanoid/graphene hybrids were formed from the partial conversion of few-layer graphene, due to the prevalent Bernal stacking sequence. Raman spectroscopy, electron diffraction, and Density Functional Theory calculations show that partial conversion generates twisted bi-layer graphene located at the interface between the upper diamanoid domain and the non-converted graphenic domain underneath. Carbon-hydrogen bonding in the basal plane of hydrogenated few-layer graphene, where carbon is bonded to a single hydrogen over an area of 150 m2, was directly evidenced by Fourier transform infrared microscopy and the actual full hydrogenation of diamane was supported by first-principle calculations. Those results open the door to large-scale production of diamane, diamanoids, and diamanoid/graphene hybrids.

Progress on Diamane and Diamanoid Thin Film Pressureless Synthesis