Comparison of electrochemical behavior of composites based on graphene oxide, poly‐o‐phenylenediamine, and heteropolyacids

Abstract

The electrochemical behavior of electroactive composites based on reduced graphene oxide (RGO), poly‐o‐phenylenediamine (PPD) and heteropolyacids (HPA) (silicotungstic [SiW] and phosphotungstic [PW]) was comparatively studied by means of cyclic voltammetry (CVA), charge–discharge galvanostatic curves, and electrochemical impedance. The composites were applied to planar screen‐printed carbon electrodes as the first step to creating various devices, in particular, sensors based on novel composites. Like RGO‐PPD‐SiW composites, RGO‐PPD‐PW composites also exhibit several redox transitions. With respect to the method of synthesis (order of applying components), RGO‐PPD‐PW can exhibit the properties of a mediator catalyst as was demonstrated for example of the redox transition in the quinone‐hydroquinone couple, where reversibility is significantly enhanced by conducting the reaction on a RGO‐PPD‐PW‐modified electrode.

Enhanced Electrochemical Response of Isoniazid Electrocatalytic Oxidation on RGO‐PPD‐SiW Modified Electrode

“…As we showed [10,11], RGO-PPD-SiW and RGO-PPD-PW composites exhibit high electroactivity in acid media. However, normal saline retains some redox peaks existing in CV in 1 M H 2 SO 4 .…”

“…Also some authors seem that oxidation of isoniazid at RGO modified electrode is an adsorption-controlled process with the participation of oxygen-containing surface groups, and high conductivity of RGO leads to makes better electron transfer across the electrode surface [32]. The importance of this peak have shown in our previous studies [10,11]. It is this potentials range, where the composite clearly demonstrates its electrocatalytic properties in acid media.…”

“…Like in an acid medium [10], in a neutral saline solution, the peak current linearly depends on the potential sweep rate (Figure 4a, b). This linear dependence demonstrates the absence of charge transfer deceleration in the bulk of the composite coating.…”

“…One of the types of our developed composites was prepared by adding heteropolyanions (HPA) to a structure comprising RGO and PPD [10,11]. This allows preparing the conducting redox active composites having good mediator catalyst properties.…”