Development of Graphene Oxide Nanofluids From Recycled Graphite: Part I—Materials Characterization

This work explores the synthesis of graphene oxide (GO) nanoflakes from recycled graphite using a modified Hummers method. The effectiveness of this approach was evaluated through comprehensive characterization techniques. Scanning electron microscopy (SEM) revealed the formation of uniform GO with stacked, flat sheets. X-ray diffraction (XRD) confirmed the presence of oxygen-containing functional groups on the GO surface by identifying a characteristic peak. Fourier transform infrared (FT-IR) spectroscopy successfully identified key functional groups (carboxyl, aromatic C═C, alkoxy, and hydroxyl) responsible for the unique properties of GO. Raman spectroscopy analysis confirmed the presence of graphene with a less distorted structure through characteristic D and G bands. However, the ID/IG ratio was not a reliable measure of interdefect distance due to the high defect density in GO. Brunauer-Emmett-Teller (BET) and BJH analysis classified the OG as a mesoporous material with a significant surface area. Thermogravimetric analysis (TGA) verified the thermal stability of GO, revealing two distinct mass losses: one due to adsorbed water elimination and another due to the decomposition of oxygenated functional groups.