Stepwise defluorination of fluorographene: How do the structural features govern the rates of heterogeneous electron transfer?

[Display omitted] •The sonochemical exfoliation of fluorographite using DMF is accompanied by a solvent assisted defluorination as well.•The prepared fluorographene systems with different sonication time possess different fluorine coverage and morphology.•The studies reveal that the HET rates may not be directly correlated to the fluorine content alone.•In partially defluorinated nanosheets (FG-8), interesting onion like nanocarbon structures are observed.•FG-8 shows HET rates with the value of ΔEp falling well below the reversible limit. Partial fluorination of graphene is known to enhance its heterogeneous electron transfer (HET) rates with a significant impact on its application as electrochemical sensors. However, the results had been rather inconclusive on the correlation between the HET rates and the degree of fluorine coverage. We address this using a top-down approach, via the step-wise defluorination of fluorographene using the solvent-assisted, sonochemical method. The results suggest that in addition to the fluorine coverage, the structural and morphological features also have a significant role in governing the HET rates. The reversible limit of HET is attained in the case of glassy carbon electrode modified with partially defluorinated fluorographene with 26% of fluorine coverage studied with the redox probe [Fe(CN)6]4−/3−, and this is correlated to the formation of the unique onion-like interconnected nanocarbon structural features. Electrochemical sensing studies with the prepared fluorographene systems using some important biomarkers like ascorbic acid (AA), uric acid (UA) and dopamine (DA) are also reported.