F2-Fluorination of Fe/N/C catalysts poisons FeN4, but not CNx sites. Main causes of instability in PEMFCs are either FeN4 demetalation for Fe/N/C or H2O2 when FeN4 sites are poisoned by fluorination or absent as in MOF_CNx_Ar + NH3.

Weakly fluorinated graphene nanosheets were efficiently prepared via fast thermal exfoliation of highly fluorinated graphite. This scalable method consists of a fast temperature increase (around 10 °C s-1) of fluorinated HOPG performed under an argon atmosphere, without any post-treatment. The mechanism of exfoliation induced by the defluorination step, evolving volatile fluorocarbons, has been highlighted thanks to thermogravimetric analysis (TGA), high temperature X-ray diffraction (HTK-XRD), X-ray Photoelectron Spectrometry (XPS) studies on temperature, and Raman and infrared spectroscopy. The advantages of the described process are its high-yield for the preparation of fluorinated graphene nanosheets, its ease of implementation and scalability. Moreover, the fluorine content drastically decreases during such a process and graphene layers are slightly functionalized, i.e. conductive contrary to the precursor.