WEB Detailed Local Analyses of Graphene Oxide under in-situ TEM Heat Treatments
Graphene oxide (GO) is a very promising material for a large range of applications [1-5]. Despite the efforts for investigating its atomic structure, which is critical for knowing its properties, several aspects remain unknown. In order to improve the knowledge of this material and to elucidate its behavior, we have conducted in-depth in-situ thermal transmission electron microscopy (TEM) studies. These works were performed in an image-corrected FEI Titan Cube operated at 80 kV using a DENS LightFire sample holder. We have combined in-situ heating (from 70 up to 1200ºC) high-resolution TEM imaging and electron energy loss spectroscopy (EELS) studies for getting all this information [6-7]. The presence of different oxygen functional groups forming the graphene oxide and their different transformations observed with the increment of temperature are discussed. Besides, the desorption of physisorbed and chemisorbed water during the treatment is also reported and the consequences of this effect within the GO are discussed. Furthermore, the stability/reversibility of the reduction process and the reabsorption of water and functional groups in the GO are investigated as well as its graphitization [6-7]. In parallel, we have also measured the electrical conductivity of GO during its reduction . All these findings improve the knowledge of this complex and heterogeneous material, which is crucial for the study of their physical and chemical properties and its future applications.
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 R.A. gratefully acknowledges the support from grant MAT2016-79776-P (AEI/FEDER, UE) and from the EU H2020 programs “Graphene Flagship” (Grant Agreement 785219 and 881603), “ESTEEM3” (Grant Agreement 823717), and Flag-ERA GATES (JTC - PCI2018-093137).