The effect of pH on particle size of hydrothermally reduced graphene oxide

Abstract

The reduction of graphene oxide (GO) was previously carried out using chemical reducing agents hydrazine, dimethyl sulfoxide (DMSO) and sodium borohydride (NaBH4). These chemical agents endanger the environment and cause reduced graphene oxide (RGO) sample to form aggregation. In this paper, RGO samples were prepared using hydrothermal synthesis under different pH mediums (pH = 4, 7 and 11). The effects of pH value on surface morphology, chemical compositions and particle sizes were investigated using field emission scanning electron microscope (FESEM), fourier transform infrared (FTIR) and Malvern Zetasizer Nano ZS. FESEM shows RGO samples present in nanosheets and wrinkled structures. FTIR indicates that the characteristic peaks of RGO are in minimum value at different pH values. Particle sizes of RGO samples prepared in different pHs vary from 344.0 nm to 751.1 nm. The particle sizes of RGO samples decrease with increasing of pH value due to electrostatic repulsion on the graphene sheets.