Electrochemical study on the intercalation properties of hydroxyl anion for the reversible conversion of graphene quantum dots into carbon dots

The intercalating property of hydroxyl anion for reversible conversion of graphene quantum dots (GQDs) into carbon dots (CDs) by electrochemical techniques such as cyclic voltammetry (CV) was studied in detail. For this purpose, the three-electrode system was a Pt disk as counter, Ag/AgCl as reference and GQDs-modified Pt disk as working electrodes. Based on the results, among various anions such as Cl-, Br-, PO43-, PO33-, NO2-, OH-, and NO3- as well as different cations like Na+, K+ and Li+, only OH- can selectively intercalate nanocarbons during reversible conversion of GQDs to CDs. According to the cyclic voltammograms at potential the same as -0.2 V (vs, Ag/AgCl) GQDs were converted into CDs. However reverse conversion of CDs into GQDs was simply occurred by continuous scanning the potential from +0.1 to -0.8 V (vs. Ag/AgCl). Effective role of OH- as selective intercalating agent was further approved using some surface analytical methods such as scanning electron microscopy (SEM), BET, BJH as well as some spectroscopic techniques such as Fourier transform-infrared (FT-IR). This study was applicable from several aspects such as i) in the intelligent controlling the morphology as well as the active surface area of nanocarbons during fabrication of carbon-based sensors ii) selective separation of OH- through the electro-filtration process, iii) selective exchange between OH- and other anionic species in the separation analyses and iv) controlling the bandgap (Fermi levels) between the inter-layers of graphene-based nanostructures through the intercalation process. (C) 2015 Elsevier B.V. All rights reserved.