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

Abstract

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.