Efficient one-pot two-step electrochemical synthesis of highly oxidized graphene oxide for enhanced energy and environmental applications: Structure elucidation through DFT simulations

Abstract

In this study, an innovative electrochemical approach for the synthesis of graphene oxide (GO) sheets is presented. The one-pot synthesis process consists of two steps: first, exfoliation of graphene sheets from an anodic graphite electrode in a sulfuric acid-phosphoric acid mixture; second, oxidation of the exfoliated graphene sheets using platinum-coated titanium dimension-stable electrodes (DSE) and KMnO4 as the oxidizing agent. One of the key aspects of this research was the investigation of the impact of synthesis conditions, such as current density (ranging from 0.125—0.3125 A cm−2) and reaction time (30—480 min), on the efficiency of graphene oxidation. A combination of XRD, Raman, TGA, FESEM, and TEM along with FT-IR, XPS, and Boehm's titration techniques were employed for the comprehensive characterization of the prepared GO sheets. Results showed that the interlayer d-spacing of various GO samples range between 0.81—0.98 nm, while ID/IG values were found to vary in the range of 0.77–0.98. The C/O ratio for the various GO samples fell within the range of 1.85–2.76, with the relative percentage of oxygen-containing functional groups as 81%. The prepare GO sheets (referred as C3) were applied for removing methylene blue (MB), rhodamine B (RhB), and methyl orange (MO) dyes from aqueous medium. The adsorption capacities of these dyes, when tested at an initial concentration of 20 ppm, were found to be 99, 97, and 23 mg/g, respectively. Additionally, these GO sheets demonstrated excellent electrochemical characteristics, demonstrating a high photocurrent of 2.47 × 10−7 A, when integrated into a perovskite photodetector. Density functional theory (DFT) further corroborates the spontaneous nature of the oxidation process of graphene sheets using this approach. In summary, this method offers an efficient approach for producing highly oxidized GO sheets suitable for energy and environmental applications.