Preparação eletrolítica e caracterização eletroquímica de nanopartículas de carbono modificadas com ABTS

Electrolytic exfoliation has been largely employed to prepare carbon nanoparticles from graphite. Highly stable graphene suspensions can be easily prepared if the electrolysis is carried out in the presence of an appropriate graphene modifier [1]. 2,2-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), in turn, is a well-known anionic and electrochromic electron mediator widely employed in colorimetric analysis of antioxidants and other important analites specially due to the high stability and oxidative capacity of its ABTS°-radical, which is deep green while its reduced form is colorless [2]. This work presents a route to prepare highly stable aqueous suspensionsof ABTS-modified graphene nanoparticles from graphite. The electrochemical characterization of the new material and details of the electrolytic preparation route arealsopresented. The as prepared ABTS-Graphene hybrid material preserves the advantageous electrochemical properties of both, graphene and ABTS (Figure 1). The peak potentials for oxidation (Epa= 0.47 V) and reduction (Epc= 0.46 V) are in close agreement to the ones observed for ABTS2-/ ABTS°-redox pair reported in literature [3]. The full width at half-heightof the peak for ABTS oxidation (at ∼0.47 V) is equal to ∼95 mV, which is somewhat closer to the theoretical value of 90 mV expected for an ideal one-electron surface-type voltammetric peak [4]. The high stability of the suspension (several months) and the observed electrochemical properties of the graphene hybrid structure may be indicativeofnon-covalent π-π interactions between graphene sheets and ABTS. The electrochemical properties of the as prepared material show it is promising for use on electrocatalysis sensing applications.