In-Situ Hydrogen-Induced Defects on the Single Layer CVD Growth Graphene

In this paper we present in-situ hydrogen-induced defects on the single layer CVD growth graphene sheets with reactive terminated edges and holes within the graphene matrix. The samples are obtained by low-pressure CVD graphene growth in hydrogendiluted methane [1]. In order to obtain graphene membranes with macroscopic selectivity towards proton transport, the hydrogen flow rate is adjusted so that it has an etching effect during the growth process [2,3]. Graphene sheets growth by CVD on copper is carried out at high temperature (~1025°C), in the large glass resistant furnace of the chemical vapor deposition system. Several parameters (gases and flows, temperature, pressure, reaction time) are adjusted. The defects and holes allow graphene layer further doping and functionalization in order to obtain protonic conductivity layers for hydrogen isotopes separation and applications. The quality and thickness uniformity of graphene is ascertained directly on the metal substrate, immediately after CVD growth, using optical microscopy. To get a good overview of the morphology of a graphene layers, such as pores distribution and defects, reactive terminated edges, and elements within the graphene matrix, the samples are studied by Field Emission Scanning Electron Microscopy (FESEM). Raman studies of the graphene is carried out in order to obtain precise information on the features of the graphene layers and the number of layers. References: Birong Luo, Enlai Gao, Dechao Geng, Huaping Wang, Zhiping Xu, and Gui Yu, Etching-Controlled Growth of Graphene by Chemical Vapor Deposition, Chem. Mater. 2017, 29, 1022−1027 Saheed Bukola, Ying Liang, Carol Korzeniewski, Joel Harris, and Stephen Creager, Selective Proton/Deuteron Transport through Nafion/Graphene/Nafion Sandwich Structures at High Current Density, J. Am. Chem. Soc. 2018, 140, 1743−1752. Qiuju Zhang, Minggang Ju, Liang Chen, and Xiao Cheng Zeng, Differential Permeability of Proton Isotopes through Graphene and Graphene Analogue Monolayer, Phys. Chem. Lett. 2016, 7, 3395−3400.