Fig. 3

FT-IR (ATR, attenuated total reflectance) spectrum of graphene oxide with proposed assignment of functional groups present in GO. The most notable peaks were observed at ~ 3500 cm⁻¹, (attributed to water and hydroxyl groups), ~ 1080 cm⁻¹ (hydroxyl groups), ~ 1600 cm⁻¹ (assigned to C=C bonds present in graphitic carbon). Other peaks observed on the FT-IR spectrum show that GO is rich in groups containing C=O (mainly carboxyl groups), peak around 1720 cm⁻¹, epoxy (C–O–C) with the visible peak around 1200 cm⁻¹, and C–H bonds (peak around 2800 cm⁻¹)