Microstructural Transformation of GO to rGO by Ascorbate Acid Green-Agent Enhanced using Sonication Method

Abstract Microstructural transformation of reduced graphene oxide (rGO) from graphene oxide (GO) was successfully carried out using ascorbic acid as a reducing agent and a sonication process to improve the reduction efficiency. The primary objectives of this study were to evaluate the role of ascorbic acid in changing the microstructure of rGO and to review the effect of sonication duration on the reduction process. Characterization of particle size distribution and electronic structure was carried out using PSA and UV-Vis, while changes in microstructure, crystallization, and morphology were analyzed using XRD, Raman spectroscopy, and SEM/EDX. The results showed that increasing the sonication duration decreased the particle size of rGO significantly, contributing to increased process efficiency. The decrease in the bandgap of rGO was also confirmed through UV-Vis characterization. FTIR analysis showed a decrease in the absorption intensity of the O=C=O (2200-2450 cm⁻¹), C-O (1024-1150 cm⁻¹), and O-H (3650-3800 cm⁻¹) peaks, indicating a decrease in oxygen groups and the restoration of the sp² structure. SEM showed a change in the morphology of the compact GO surface to a looser and folded rGO, with a decrease in the oxygen ratio detected by elemental mapping. The increase in the intensity of the D band in the Raman spectrum indicated an increase in structural defects due to the reduction of oxygen groups. Crystallite size calculations from Raman and XRD revealed that rGO had a smaller crystallite size than GO, where rGO with a sonication duration of 120 minutes had a smaller crystallite size than rGO with 180 minutes, indicating an expansion of the sp² domain. The combination of ascorbic acid and sonication proved effective in reducing GO to rGO with significant improvements in material characteristics.