Synthesis and characterization of graphene oxide (GO) and reduced graphene oxide (rGO) using Modified Tour’s method for sensing device applications

Graphene oxide (GO) and reduced graphene oxide (rGO) have successfully synthesized using modified Tour’s method with end product having rapid purification rate, hydrophobic condition and conductive material. Prominent green reducing agent namely ascorbic acid has used in the GO sample preparation and act as reductant which help removal of oxygen containing functional group hence, resultant of rGO. In this investigation, the GO purification rate has accelerated by help of sodium hydroxide (NaOH) in function of washing agent with only 3 cycle’s wash. Raman spectroscopy results show that the synthesized GO and rGO samples yield in the range of 1349.33 cm$^{-1}$ (D band) to 1571.35 cm$^{-1}$ (G band) of Raman peak, respectively. A narrow and sharp Raman peak with high intensity of rGO sample has indicates it having a better quality as compared to GO sample. Contact angle measurement reveal the large angle obtained from rGO sample which are 72.8° on left hand side and 65.0° for right side, correspondingly have confirmed it is more hydrophobic than GO which attained contact angle of 52.5° on both sides. Surface morphology examined by Field Emission Scanning Electron Microscope (FE-SEM) show that both samples that diluted with deionized (DI) water have a loose sponge which similar to a thin wrinkle sheet in structure that suggest it has well exfoliated by using modified Tour’s method. On the other hand, produced samples that not diluted with DI water has tightly packed, corrugated and crumpled in form. Results from Energy Dispersive Spectroscopy (EDS) measurement has confirmed that oxygen-containing functional group have been removed from rGO sample by having higher calculated carbon / oxygen (C / O) in quotient with 3.09 as compared to GO sample with 1.43 which based on the atomic percentage of C/O. The significant reduction of resistance value from rGO sample with $33.41 \times 10^{4}\Omega$ as compared to GO with $41.18 \times 10^{6} \Omega$ have leading it to obtained better conductivity with $4.77 \times 10^{-7}$ S / cm in comparison to GO sample with $3.86 \times 10^{-9}$S / cm. Thus, this modified Tour’s method with the usage of green reductant agent has potential to be used in producing sensing device applications.