Contributed Speaker
Lydia Chibane
Correlative metrology for the study of the physico-chemical properties of graphene oxide during its reduction
Alexandra Delvallée¹, Nolwenn Fleurence¹, José Morán¹, Nicolas Feltin¹, Emmanuel Flahaut²
¹ Laboratoire National de métrologie et d’Essais (LNE) – DMSI – Nanométrologie, 29 avenue Roger Hennequin, 78197 Trappes (France)
² Centre Inter-universitaire de Recherche et d’Ingénierie des Matériaux (CIRIMAT)
UMR CNRS 5085, 118 Route de Narbonne, 31062 Toulouse
For some years now, the most widely studied 2D material has been graphene, which has aroused the interest and curiosity of researchers (over 250,000 publications since 2000). This material is obtained by various processes, but the least costly and time-consuming is graphene oxide (GO) reduction. However, the 2D material produced by this process differs from perfect graphene in terms of physico-chemical properties. This is why it is necessary to develop reliable technical tools and measurement methods to qualify these properties and ensure a similar quality in the production of the different batches.
However, there is no single technique for the comprehensive physico-chemical characterization of graphene, and GRMs (Graphene-related Materials) in general. In fact, each technique has its own strengths and weaknesses, and provides only quantitative information based on a single physico-chemical parameter. The only way to overcome such limitations on a single object and obtain the most comprehensive data is to combine different techniques.
In this study, we propose an advanced characterization of 2D materials, graphene oxide (GO) and reduced graphene oxide (rGO), prepared by thermal reduction in hydrogen. A method for correlating microscopy/spectroscopy techniques on individual flakes is developed. This involves analyzing exactly the same flake of sample with the different techniques in order to understand the link between its properties, and eventually be able to control them for specific applications. The techniques used are: AFM and its derivatives (scanning thermal microscopy (SThM), scanning microwave microscopy (SMM)), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Raman spectroscopy/microscopy and X-ray photoelectron spectroscopy (XPS).
This correlative approach means that the limitations of each technique must be addressed, for example when selecting the substrate - which must then be suitable for all the methods used. For each technique, the methods must be perfectly matched to minimize damage to the material during analysis. Ultimately, a process strategy needs to be developed to ensure that, during this correlative microscopy approach, 2D localization of the material is facilitated, and that the least invasive techniques are used before the most invasive, in order to minimize material damage during the investigation procedure.
The aim of this presentation is to show strategies used to obtain the physico-chemical properties of a single flake of GO with the correlative microscopy approach developed.